Abstract: Additive Manufacturing is widely applied in aerospace, automotive and marine engineering. Indeed, large-scale components are often required in these applications, such as for non-structural parts of aircraft, spare parts or small lots of cars or marine components. Fused Deposition Modelling is one of the Additive Manufacturing processes used to affordably convert digital models into mockups, prototypes, and functional parts: a slicing software converts the object’s digital model into a list of instructions for the machine. However, commercial slicing software packages often fail to accurately estimate the time required to produce models, especially when their size is significant: the errors could be up to several hours, which cannot be adequate in a real-life industrial context where production must be scheduled in a precise way. This manuscript compares the build time estimation of several commercial slicing software considering a real-life part. Furthermore, the evaluation of the manufacturing setting mainly affects the error in estimating the build time achieved through a Design of Experiment approach. The more time-impacting printing parameters have been detected, allowing fine helpful tuning to increase the accuracy of the build time in commercial slicing software. A case study included in the manuscript supports the analyses. Proper setting of the commercial slicing software can significantly improve the accuracy of the printing time.

Keywords: Additive Manufacturing | Design of Experiment | Fused Deposition Modelling | Slicing | Time Estimation

Abstract: The topology optimization methodology is widely utilized in industrial engineering for designing lightweight and efficient components. In this framework, considering natural frequencies is crucial for adequately designing components and structures exposed to dynamic loads, as in aerospace or automotive applications. The scientific community has shown the efficiency of Bi-directional Evolutionary Structural Optimization (BESO), showcasing its ability to converge towards optimal solid-void or bi-material solutions for a wide range of frequency optimization problems in continuum structures. However, these methods show limits when the complexity of the domain volume increases; thus, they are well-suited for academic case studies but may fail when dealing with industrial applications that require more complex shapes. The connectivity of the structures resulting from the optimization also plays a fundamental role in choosing the best optimization approach, as some available commercial and open-source codes nowadays return unfeasible sparse structures. An improved voxel-based BESO algorithm has been developed in this work to cope with current limits in lightweight structure optimization. A significant case study has been developed to evaluate the performances of the new methodology and compare it with existing algorithms. In contrast to previous studies, the method we developed guarantees that the final structure respects constraints on the initial design volume and that the structure’s connection is preserved, thus enabling the manufacturing of the component with Additive Manufacturing technologies. The proposed approach can be complemented by smoothing algorithms to obtain a structure with externally appealing surfaces.

Keywords: Additive manufacturing | Bi-directional evolutionary structural optimization (BESO) | Natural frequency | Optimal design | Topology optimization

Abstract: Air pollution causes many diseases and is a major environmental threat, therefore, it is essential to monitor and improve the air quality. With this work, we aim to assess atmospheric pollution using drone-mounted air sensors, with specific applications in Vietnam. We aim to measure Green-House Gas (GHG) emissions and other pollutants in urban and non-urban areas of interest including, but not limited to landfills and airports, to evaluate the effects of pollution on climate and health. The project will use a novel and creative approach to collect three-dimensional atmospheric data using smart sensors mounted on Unmanned Aerial Vehicles (UAVs). UAVs have been extensively applied in recent years, both in Vietnam and on a global scale, to multiple fields and with different scopes. Surveying, crop monitoring, irrigation and fertilization, surveillance and rescue support, and 2D and 3D mapping, are just a few examples of how UAVs can be used for agriculture, archaeology, forestry, urban planning, and architecture. In this project, we develop an integrated system of UAVs and smart sensors for air quality monitoring. To develop mitigation and adaptation strategies for reducing the environmental impact of transport, it is imperative to assess the emission sources and trends. Therefore, we are developing a system able to collect comprehensive atmospheric data using remote aerosol sampling, and chemical speciation. Furthermore, the potential of using smart sensors on other flying devices is explored.

Keywords: Air pollution | air quality monitoring | Unmanned Aerial Vehicles

Abstract: Over the past few decades, the scientific community’s and industry’s interest in additive manufacturing technologies has surged. This technology is distinguished by the layer-by-layer deposition of the raw materials and the piece’s growth in a predetermined build orientation. This factor impacts the process’ overall cost, surface quality, and other crucial parameters. Numerous methods to solve competing aspects have been proposed in the literature, with the more promising that iteratively uses ray-tracing techniques. Existing algorithms iterate for each discrete element of the model’s bounding box projection onto the building platform. However, when optimisation algorithms are used on real-life industrial parts, computational time problems arise due to the high number of faces in the models. A new computational technique to determine the appropriate part orientation to reduce the support volume is proposed to address the problem. The method reduces the computational time, cycling the ray-tracing only on the triangles where the model surface is discretised. This approach has been integrated into an enhanced particle swarm optimisation algorithm to prove its efficiency. The approach is intended for industrial applications where it is necessary to handle complicated geometries quickly and efficiently to find the best orientation. Based on the computer’s resources and the complexity of the faceted model, a set of case studies with an industrial engineering significance is used to demonstrate the approach’s effectiveness.

Keywords: Additive manufacturing | Build orientation | Part orientation | Particle swarm optimisation | Support material

Abstract: Natural disasters have a significant effect in terms of impacted individuals and casualties. Artificial Intelligence (AI) techniques for automatically segmenting landslides from aerial photos is a relatively new field of research. Segmenting landslips quickly and accurately can significantly aid in assessing the damage caused by natural disasters. This research aims to compare the performance of AI techniques with more classical methods for the automatic segmentation of landslides from aerial images for damage assessment. It is presented a dataset of satellite images containing landslides collected in the Broni (Italy) region and annotated to train and test the segmentation model. Both classical image processing techniques, such as thresholding and edge detection, and AI-based methods, such as U-Net, are applied to the dataset. Overall, this research demonstrates that AI-based methods are a promising tool for automatically segmenting landslides from aerial images and can be a powerful asset in assessing the damage caused by natural disasters. The study also highlights the importance of combining classical and AI-based methods for better performance, especially in challenging and complex scenes.

Keywords: Artificial Intelligence | Damage Assessment | Landslips | Semantic Segmentation

Abstract: Additive Manufacturing (AM) is continuously increasing its appeal as a breakthrough production process due to well-established advantages compared to traditional manufacturing strategies based on chip removal or casting. The design of lightweight structures can exploit the AM advantages, thanks to the capability of shaping complex geometries where the constant level of stress can be achieved through Topology Optimization. Moreover, in transportation engineering and lightweight structures in general, thin-shell or thin-walled components are widely used for frames, fuselages, wings, car bodies, coaches, tanks or recipients. However, the application of topology optimization routines on thin-walled structures is not exempt from difficulties. This is true especially in the case of a distributed pressure load coming from fluid-structure interaction analysis. Coupling the benefits of TO methodology with the already good performances of thin-walled structures may lead to mechanically efficient shapes. This research addresses strategies to apply topology optimization on thin-walled structures. The effect of the local concentration of distributed load in a cloud of control points distributed along the surface of interest is considered and tested. Two case studies coming from industrial engineering have been carried out to show the capabilities of the proposed approach.

Keywords: Additive Manufacturing | Design for Additive Manufacturing | Distributed load | Thin-walled structure | Topology Optimization

Abstract: Nowadays, Search and Rescue operations can be performed using manned or unmanned Aerial Vehicles. In this latter case, compact cameras are mounted onboard and a bird’s eye view is available to find the missing person. However, the analysis of the video frames can be very challenging and dull for the operators. In this context, the use of graphical methodologies can boost the searching operations and improve the process. In this study, a methodology based on the object detector Yolov5 is introduced: the performances in detecting small objects such as persons in aerial images are evaluated. These algorithms implement shallow layers of the feature extractor to increase the spatial-rich features and help the detector to find small objects. Finally, detection algorithms are tested using a video simulating a scenario for Search and Rescue operations. The filtering of frames containing false positives, is carried out using a classical graphical tool such as the Hamming distance.

Keywords: Aerial images | Graphical methodologies | Image analysis | Object detection | SAR operations

Abstract: This paper investigates the effect of the Dynamically Morphing Leading Edge (DMLE) on the flow structure and the behavior of dynamic stall vortices around a pitching UAS-S45 airfoil with the objective of controlling the dynamic stall. An unsteady parametrization framework was developed to model the time-varying motion of the leading edge. This scheme was then integrated within the Ansys-Fluent numerical solver by developing a User-Defined-Function (UDF), with the aim to dynamically deflect the airfoil boundaries, and to control the dynamic mesh used to morph and to further adapt it. The dynamic and sliding mesh techniques were used to simulate the unsteady flow around the sinusoidally pitching UAS-S45 airfoil. While the (Formula presented.) turbulence model adequately captured the flow structures of dynamic airfoils associated with leading-edge vortex formations for a wide range of Reynolds numbers, two broader studies are here considered. Firstly, (i) an oscillating airfoil with the DMLE is investigated; the pitching-oscillation motion of an airfoil and its parameters are defined, such as the droop nose amplitude ((Formula presented.)) and the pitch angle at which the leading-edge morphing starts ((Formula presented.)). The effects of the (Formula presented.) and the (Formula presented.) on the aerodynamic performance was studied, and three different amplitude cases are considered. Secondly, (ii) the DMLE of an airfoil motion at stall angles of attack was investigated. In this case, the airfoil was set at stall angles of attack rather than oscillating it. This study will provide the transient lift and drag at different deflection frequencies of 0.5 Hz, 1 Hz, 2 Hz, 5 Hz, and 10 Hz. The results showed that the lift coefficient for the airfoil increased by 20.15%, while a 16.58% delay in the dynamic stall angle was obtained for an oscillating airfoil with DMLE with (Formula presented.) = 0.01 and (Formula presented.) = 14.75°, as compared to the reference airfoil. Similarly, the lift coefficients for two other cases, where (Formula presented.) = 0.05 and (Formula presented.) = 0.0075, increased by 10.67% and 11.46%, respectively, compared to the reference airfoil. Furthermore, it was shown that the downward deflection of the leading edge increased the stall angle of attack and the nose-down pitching moment. Finally, it was concluded that the new radius of curvature of the DMLE airfoil minimized the streamwise adverse pressure gradient and prevented significant flow separation by delaying the Dynamic Stall Vortex (DSV) occurrence.

Keywords: dynamic stall | Dynamically Morphing Leading Edge (DMLE) | flow control | morphing | unsteady parameterization

Abstract: Industrial engineering applications often require manufacturing large components in composite materials to obtain light structures; however, moulds are expensive, especially when manufacturing a limited batch of parts. On the one hand, when traditional approaches are carried out, moulds are milled from large slabs or laminated with composite materials on a model of the part to produce. In this case, the realisation of a mould leads to adding time-consuming operations to the manufacturing process. On the other hand, if a fully additively manufactured approach is chosen, the manufacturing time increases exponentially and does not match the market’s requirements. This research proposes a methodology to improve the production efficiency of large moulds using a hybrid technology by combining additive manufacturing and milling tools. A block of soft material such as foam is milled, and then the printing head of an additive manufacturing machine deposits several layers of plastic material or modelling clay using conformal three-dimensional paths. Finally, the mill can polish the surface, thus obtaining a mould of large dimensions quickly, with reduced cost and without needing trained personnel and handcraft polishing. A software tool has been developed to modify the G-code read by an additive manufacturing machine to obtain material deposition over the soft mould. The authors forced conventional machining instructions to match those of an AM machine. Thus, additive deposition of new material uses 3D conformal trajectories typical of CNC machines. Consequently, communication between two very different instruments using the same language is possible. At first, the code was tested on a modified Fused Filament Fabrication machine whose firmware has been adapted to manage a milling tool and a printing head. Then, the software was tested on a large machine suitable for producing moulds for the large parts typical of marine and aerospace engineering. The research demonstrates that AM technologies can integrate conventional machinery to support the composite materials industry when large parts are required.

Keywords: additive manufacturing | aerospace engineering | Fused Filament Fabrication | G-code | hybrid manufacturing | marine engineering | mould

Abstract: In situations requiring high levels of customization and limited production volumes, additive manufacturing (AM) is a frequently utilized technique with several benefits. To properly configure all the parameters required to produce final goods of the utmost quality, AM calls for qualified designers and experienced operators. This research demonstrates how, in this scenario, artificial intelligence (AI) could significantly enable designers and operators to enhance additive manufacturing. Thus, 48 papers have been selected from the comprehensive collection of research using a systematic literature review to assess the possibilities that AI may bring to AM. This review aims to better understand the current state of AI methodologies that can be applied to optimize AM technologies and the potential future developments and applications of AI algorithms in AM. Through a detailed discussion, it emerges that AI might increase the efficiency of the procedures associated with AM, from simulation optimization to in-process monitoring.

Keywords: Additive manufacturing | Artificial intelligence | Deep learning | Machine learning | Optimization | Review

Abstract: Purpose: Timing constraints affect the manufacturing of traditional large-scale components through the material extrusion technique. Thus, researchers are exploring using many independent and collaborative heads that may work on the same part simultaneously while still producing an appealing final product. The purpose of this paper is to propose a simple and repeatable approach for toolpath planning for gantry-based n independent extrusion heads with effective collision avoidance management. Design/methodology/approach: This research presents an original toolpath planner based on existing slicing software and the traditional structure of G-code files. While the computationally demanding component subdivision task is assigned to computer-aided design and slicing software to build a standard G-code, the proposed algorithm scans the conventional toolpath data file, quickly isolates the instructions of a single extruder and inserts brief pauses between the instructions if the non-priority extruder conflicts with the priority one. Findings: The methodology is validated on two real-life industrial large-scale components using architectures with two and four extruders. The case studies demonstrate the method's effectiveness, reducing printing time considerably without affecting the part quality. A static priority strategy is implemented, where one extruder gets priority over the other using a cascade process. The results of this paper demonstrate that different priority strategies reflect on the printing efficiency by a factor equal to the number of extrusion heads. Originality/value: To the best of the authors’ knowledge, this is the first study to produce an original methodology to efficiently plan the extrusion heads' trajectories for a collaborative material extrusion architecture.

Keywords: Additive manufacturing | Collaborative manufacturing | FDM | MEX | Multiple heads | Toolpath planning

Abstract: This study aims to evaluate the advantages and criticalities of applying additive manufacturing to produce climbing holds replicating real rocky surfaces. A sample of a rocky surface has been reproduced with a budget-friendly 3D scanner exploiting structured light and made in additive manufacturing. The methodology is designed to build a high-fidelity replica of the rocky surface using only minor geometry modifications to convert a 2D triangulated surface into a 3D watertight model optimised for additive manufacturing. In addition, the research uses a novel design and uncertainty estimation approach. The proposed methodology proved capable of replicating a rocky sample with sub-millimetre accuracy, which is more realistic than conventional screw-on plastic holds currently used in climbing gyms. The advantages can be addressed in terms of customisation, manufacturing cost and time reduction that could lead to real outdoor climbing experiences in indoor environments by coupling additive manufacturing techniques and reverse engineering (RE). However, operating the scanner in a rocky environment and the considerable size of the climbing routes suggest that further research is needed to extend the proposed methodology to real case studies. Further analysis should focus on selecting the best material and additive manufacturing technology to produce structural components for climbing environments.

Keywords: 3D scanning | Additive manufacturing | Climbing holds | Fused deposition modelling | Reverse engineering | Uncertainty quantification

Abstract: This paper investigates the effect of the optimised morphing leading edge (MLE) and the morphing trailing edge (MTE) on dynamic stall vortices (DSV) for a pitching aerofoil through numerical simulations. In the first stage of the methodology, the optimisation of the UAS-S45 aerofoil was performed using a morphing optimisation framework. The mathematical model used Bezier-Parsec parametrisation, and the particle swarm optimisation algorithm was coupled with a pattern search with the aim of designing an aerodynamically efficient UAS-45 aerofoil. The transition turbulence model was firstly applied to predict the laminar to turbulent flow transition. The morphing aerofoil increased the overall aerodynamic performances while delaying boundary layer separation. Secondly, the unsteady analysis of the UAS-S45 aerofoil and its morphing configurations was carried out and the unsteady flow field and aerodynamic forces were analysed at the Reynolds number of 2.4 × 106 and five different reduced frequencies of k = 0.05, 0.08, 1.2, 1.6 and 2.0. The lift (, drag ( and moment ( coefficients variations with the angle-of-Attack of the reference and morphing aerofoils were compared. It was found that a higher reduced frequencies of 1.2 to 2 stabilised the leading-edge vortex that provided its lift variation in the dynamic stall phase. The maximum lift and drag coefficients and the stall angles of attack are evaluated for all studied reduced frequencies. The numerical results have shown that the new radius of curvature of the MLE aerofoil can minimise the streamwise adverse pressure gradient and prevent significant flow separation and suppress the formation of the DSV. Furthermore, it was shown that the morphing aerofoil delayed the stall angle-of-Attack by 14.26% with respect to the reference aerofoil, and that the of the aerofoil increased from 2.49 to 3.04. However, while the MTE aerofoil was found to increase the overall lift coefficient and the , it did not control the dynamic stall. Vorticity behaviour during DSV generation and detachment has shown that the MTE can change the vortices' evolution and increase vorticity flux from the leading-edge shear layer, thus increasing DSV circulation. The conclusion that can be drawn from this study is that the fixed drooped morphing leading edge aerofoils have the potential to control the dynamic stall. These findings contribute to a better understanding of the flow analysis of morphing aerofoils in an unsteady flow.

Keywords: dynamic stall | laminar separation bubble | morphing leading edge | morphing trailing edge | optimization | reduced frequency

Abstract: The unsteady flow characteristics and responses of the UAS-S45 airfoil with a morphing trailing edge shape at high angles of attack undergoing deflections are investigated at a Reynolds number of 2.4 × 106. The flexible trailing edge was simulated using a computational fluid dynamics approach using a dynamic mesh and user-defined functions. The goal was to achieve a dynamically deflected trailing edge in an unsymmetrical airfoil and assess the influence of unsteady morphing trailing edge deflection on transient forces and flow field unsteadiness. The steady aerodynamic characteristics of the morphing deflection and the conventional deflection was initially studied. Then, the unsteady aerodynamic characteristics of the morphing wing was investigated as the trailing edge deflects at different rates. The dynamic flow responses to downward deflections are studied using the turbulence model. The time histories of the lift and drag coefficient responses exhibit a proportional relationship between the morphing frequency and the slope of response at which these parameters evolve. Coefficients of lift, drag, and moment of the deflected trailing edge airfoils were compared to those of the reference airfoils for various angles of attack. The numerical results show that the transient lift coefficient in the deflection process was higher than that of the static case at different angles of attack. The transient lift coefficient were higher as the deflection frequency increased. It was also revealed that the trailing edge deflection did not favor the flow reattachment. In addition, the dynamic mesh strategy, cell quality, and the proposed method of deforming the morphing trailing-edge was presented

Keywords: computational fluid dynamics (CFD); aerodynamics | Dynamic Mesh | Frequency analysis | Morphing Trailing Edge

Abstract: Well-established advantages as design freedom, acceleration of design-to-manufacturing cycle, decreased internal logistics reflect on the wider application of Additive Manufacturing as the main manufacturing process. However, its application to large-scale components manufacturing is still an open challenge, because of the limited printing volume available in off-the-shelf machines, slow manufacturing process, and low production volume. After a review of the available contributions, this paper proposes a methodology to handle large-scale 3D models, to be applied before the slicing process. The methodology is based upon the large-scale component subdivision into subparts within CAD environments, using an innovative approach tailored to the problem, and exploits the multi-head capability of collaborative large-scale AM machines. A UAV fixed-wing shows the positive effects in terms of speeding up the manufacturing process. The approach can significantly reduce the printing time of large parts, but a new generation of Additive Manufacturing machines is required to exploit the methodology.

Keywords: Additive Manufacturing | Aerospace | Automotive | Collaborative Manufacturing | Large-Scale Part | Multi-head Extruder

Abstract: The panel method is a potential-flow numerical approach that shows valuable performances to solve aerodynamic problems in the preliminary design stages. It shows a lower computational effort compared with Computational Fluid Dynamics, wind tunnel tests or ‘on the field’ experiments. However, the 3D surface discretization in rectangular panels is tedious and must be often carried out manually from scratch. Moreover, the panel method can’t be used to compute the overall drag force due to strong assumptions. To solve these two challenging aspects, the authors propose a voxel-based fluid dynamic approach integrating its programmed functions within a panel method. Voxelization is used to automatically distribute coherently the panels along the external surface of a 3D model in an automated way. A parametric study is included to demonstrate how the voxel resolution affects the aerodynamic results and provide guidelines for future research. Overall drag is estimated using corrections for both the skin friction and the form drag sources. The Ahmed body case study is included and demonstrates a good agreement between the voxel-based fluid dynamics approach and the literature benchmarking values, but with lower computational efforts. Further studies involving more complex shapes should be performed to better understand the performances and limitations of the approach.

Keywords: Ahmed body | Automotive | CAD | Conceptual Design | Panel method | Voxelization

Abstract: This novel research evaluates how an adaptive winglet can improve an aircraft flight performance. A one-rotation axis adaptive winglet was designed and applied to the CRJ700 aircraft. Then, using a validated aerodynamic model, several winglet deflection angles were analyzed for several flight conditions of the CRJ700. The paper shows that the lift-over-drag ratio or the fitness of the aircraft was improved by up to 5.42% using an adaptive winglet for typical CRJ700 cruise conditions. Finally, it was simulated aerodynamic performance during a cruise performed at Mach number 0.75. This research shows that the adaptive winglet allows a regional aircraft such the CRJ700 to improve its cruise performance in terms of lift, drag of lift-to-drag ratio. Moreover, it has shown that the adaptive configuration allows to customize the optimization criteria in flight, which is an interesting advantage.

Abstract: One of the open issues in additive manufacturing is the design of conformal lattice structures, leading to an optimal layout of the struts in the design domain. This paper aims to compare different struts distributions in conformal lattices via low computational power methods in a CAD environment. Four approaches for a wireframe virtual model definition are presented for a simple cubic conformal lattice structure. An iterative variable diameter optimization method and two linear structural analyses based on mono-dimensional elements and different theories are compared. These verification methods widen the capability of checking the results so the user can compute the deformation of 3D periodic structures, or other visual results, without spending a huge amount of time and computational power. Results show that both the analysis methods give reliable results and the struts layout based on trivariate NURBS shows the most flexible solution allowing for a real-time variation of the boundary condition.

Keywords: Additive manufacturing | Conformal lattice structure | Design for additive manufacturing | Size optimization | Virtual modeling

Abstract: The Panel method is an approach for the estimation of the lift of 3D models which is faster than CFD. This can be useful especially in the conceptual design stage where several configurations should be evaluated in a reduced time with a limited computational cost. However, the meshing of the 3D body surface with rectangular panels can be a time-consuming activity because the designer should define from scratch a cloud of points that matches the external surfaces of the tested object to obtain consistent panelling. Therefore, a voxelization-based methodology has been developed to obtain the panels’ position, speeding up and automating the model preparation process. The obtained discretization has been integrated into a panel method available in the literature. Four case studies, of increasing complexity, have been analyzed to investigate the capability of the innovative voxel-based panel methodology. A parametric study has been carried out to study the effect of the voxel grid dimension on the accuracy of the results. Benchmarking values of lift coefficient obtained from literature or xFoil software have been used to evaluate the precision that can be achieved with this approach. The results show a good agreement between the voxel-based panel method and the literature when the overall pressure distributions and aerodynamic coefficient values are considered. Higher errors are noticed with drag.

Keywords: Fluid dynamics | Panel method | Potential flow | Voxelization

Abstract: Purpose: In the redesign process of assembly components that need adaptation to robotic assembly, designers can find support from structured methodologies for innovation, such as the theory of inventive problem solving (TRIZ). This paper aims to illustrate the authors’ methodology for redesigning gas hobs components for adaptation to robotic assembly. Design/methodology/approach: A designer approaching a redesign task of an assembly component of any kind for adaptation to robotic assembly must consider, first of all, the features and limitations of existing robotic assembly systems; the generation of new design ideas that best fit the requirements may result to be a very challenging task. Here, the TRIZ methodology has proven useful for generating design ideas and finding the best solution. Findings: The authors’ methodology approaches the challenges of redesign tasks for robotic assembly adaptation, which exploits knowledge of automatic and robotic assembly systems and the TRIZ method for innovation; it has proven useful in the redesign, checks and prototyping of gas hobs components. Originality/value: This paper shows how the TRIZ methodology can be integrated into the redesign process and its impact on an industrial environment. The work’s main value is to provide a set of steps to help the designers change their design components approach that is necessary but not still implemented to optimize the use of the automation. © 2022, Emerald Publishing Limited.

Keywords: Design for automatic assembly | Process modeling | Redesign | Robotic assembly | TRIZ method

Abstract: In the last decades, the flourishing of Additive Manufacturing (AM) promoted innovative design solutions in many different sectors. Despite the numerous advantages of AM technology, there are still open challenges in the field. In Fused Deposition Modelling (FDM) structures the layer-by-layer manufacturing process induces anisotropy in the material properties of the structures. The correct characterization of the mechanical properties is fundamental in the design and development stages but at the same time difficult to achieve. The experimental approach can be extremely long and expensive. An alternative is the use of an accurate numerical approach and performing a Finite Element Analysis (FEA) of the geometry which is effectively printed. However, to the best of the authors' knowledge, there is not a common and well-established procedure to reconstruct the real geometry which is generated after the slicing process. In this paper, starting from the information provided by the G-CODE, an easy-to-use, and reproducible methodology to reconstruct the printed geometry is presented. The performance of the innovative approach is evaluated via qualitative observations by referring to several case studies. The results are thoroughly analysed, and future trends and research needs are highlighted.

Keywords: Additive Manufacturing | CAD | Fused Deposition Modelling | G-CODE

Abstract: Lightweight bioinspired structures are extremely interesting in industrial applications for their known advantages, especially when Additive Manufacturing technologies are used. Lattices are composed of axial elements called ligaments: Several unit cells are repeated in three directions to form bodies. However, their inherent structure complexity leads to several problems when lattices need to be designed or numerically simulated. The computational power needed to capture the overall component is extremely high. For this reason, some alternative methodologies called homogenization methods were developed in the literature. However, following these approaches, the designers do not have a local visual overview of the lattice behavior, especially at the ligament level. For this reason, an alternative mono-dimensional (1D) modeling approach, called lattice-to-1D is proposed in this work. This method approximates the ligament element with its beam axis, uses the real material characteristics, and gives the cross-sectional information directly to the solver. Several linear elastic simulations, involving both stretching and bending dominated unit cells, are performed to compare this approach with other alternatives in the literature. The results show a comparable agreement of the 1D simulations compared with homogenization methods for real tridimensional (3D) objects, with a dramatic decrease of computational power needed for a 3D analysis of the whole body.

Keywords: homogenization | lattice structure | periodic structure | structural analysis | voxel

Abstract: This work presents an aerodynamic and structural optimization for a Droop Nose Leading Edge Morphing airfoil as a high lift device for the UAS-S45. The results were obtained using three optimization algorithms: coupled Particle Swarm Optimization-Pattern Search, Genetic Algorithm, and Black Widow Optimization algorithm. The lift-to-drag ratio was used as the fitness function, and the impact of the choice of optimization algorithm selection on the fitness function was evaluated. The optimization was carried out at various Mach numbers of 0.08, 0.1, and 0.15, respectively, and at the cruise and take-off flight conditions. All these optimization algorithms obtained effectively comparable lift-to-drag ratio results with differences of less than 0.03% and similar airfoil geometries and pressure distributions. In addition, an unsteady analysis of a Variable Morphing Leading Edge airfoil with a dynamic meshing scheme was carried out to study its flow behaviour at different angles of attack and the feasibility of leading-edge downward deflection as a stall control mechanism. The numerical results showed that the variable morphing leading edge reduces the flow separation areas over an airfoil and increases the stall angle of attack. Furthermore, a preliminary investigation was conducted into the design and sensitivity analysis of a morphing leading-edge structure of the UAS-S45 wing integrated with an internal actuation mechanism. The correlation and determination matrices were computed for the composite wing geometry for sensitivity analysis to obtain the parameters with the highest correlation coefficients. The parameters include the composite material qualities, thickness, ply angles, and the ply stacking sequence. These findings can be utilized to design the flexible skin optimization framework, obtain the target droop nose deflections for the morphing leading edge, and design an improved model

Keywords: algorithms | composite | correlation matrix | morphing airfoil | optimization | unsteady aerodynamics

Abstract: An important issue when designing conformal lattice structures is the geometric modeling and prediction of mechanical properties. This paper presents suitable methods for obtaining optimized conformal lattice structures and validating them without the need for high computational power and time, enabling the designer to have quick feedback in the first design phases. A wire-frame modeling method based on non-uniform rational basis spline (NURBS) free-form deformation (FFD) that allows conforming a regular lattice structure inside a design space is presented. Next, a previously proposed size optimization method is adopted for optimizing the cross-sections of lattice structures. Finally, two different commercial finite element software are involved for the validation of the results, based on Euler–Bernoulli and Timoshenko beam theories. The findings highlight the adaptability of the NURBS-FFD modeling approach and the reliability of the size optimization method, especially in stretching-dominated cell topologies and load conditions. At the same time, the limitation of the structural beam analysis when dealing with thick beams is noted. Moreover, the behavior of different kinds of lattices was investigated.

Keywords: Additive manufacturing | Conformal lattice structure | Design for additive manufacturing | Size optimization | Virtual modeling

Abstract: This study aims to evaluates how an adaptive winglet during flight can improve aircraft aerodynamic characteristics of the CRJ700. The aircraft geometry was slightly modified to integrate a one-rotation axis adaptive winglet. Aerodynamic characteristics of the new adaptive design were computed using a validated high-fidelity aerodynamic model developed with the open-source code OpenFoam. The aerodynamic model successively uses the two solvers simpleFoam and rhoSimple-Foam based on Reynold Averaged Navier Stokes equations. Characteristics of the adaptive winglet design were studied for 16 flight conditions, representative of climb and cruise usually considered by the CRJ700. The adaptive winglet can increase the lift-to-drag ratio by up to 6.10% and reduce the drag coefficient by up to 2.65%. This study also compared the aerodynamic polar and pitching moment coefficients variations of the Bombardier CRJ700 equipped with an adaptive versus a fixed winglet.

Keywords: Adaptive | Aerodynamic | Longitudinal | Morphing | OpenFoam | Optimization | Subsonic | Transonic | Winglet

Abstract: The topology optimization methodology is widely applied in industrial engineering to design lightweight and efficient components. Despite that, many techniques based on structural optimization return a digital model that is far from being directly manufactured, mainly because of surface noise given by spikes and peaks on the component. For this reason, mesh post-processing is needed. Surface smoothing is one of the numerical procedures that can be applied to a triangulated mesh file to return a more appealing geometry. In literature, there are many smoothing algorithms available, but especially those based on the modification of vertex position suffer from high mesh shrinkage and loss of important geometry features like holes and surface planarity. For these reasons, an improved vertex-based algorithm based on Vollmer’s surface smoothing has been developed and introduced in this work along with two case studies included to evaluate its performances compared with existent algorithms. The innovative approach herein developed contains some sub-routines to mitigate the issues of common algorithms, and confirms to be efficient and useful in a real-life industrial context. Thanks to the developed functions able to recognize the geometry feature to be frozen during the smoothing process, the user’s intervention is not required to guide the procedure to get proper results.

Keywords: Additive manufacturing | Mesh processing | Structural manufacturing | Surface smoothing | Topology optimization

Abstract: Nowadays additive manufacturing is affected by a rapid expansion of possible applications. It is defined as a set of technologies that allow the production of components from 3D digital models in a short time by adding material layer by layer. It shows enormous potential to support wind musical instruments manufacturing because the design of complex shapes could produce unexplored and unconventional sounds, together with external customization capabilities. The change in the production process, material and shape could affect the resulting sound. This work aims to compare the music performances of 3D-printed trombone mouthpieces using both Fused Deposition Modelling and Stereolithography techniques, compared to the commercial brass one. The quantitative comparison is made applying a Design of Experiment methodology, to detect the main additive manufacturing parameters that affect the sound quality. Digital audio processing techniques, such as spectral analysis, cross-correlation and psychoacoustic analysis in terms of loudness, roughness and fluctuation strength have been applied to evaluate sounds. The methodology herein applied could be used as a standard for future studies on additively manufactured musical instruments.

Keywords: Additive manufacturing | Design of experiment | Musical instruments | Sound analysis | Stereolithography

Abstract: This paper describes a methodology to design and optimize a controllable pitch propeller suitable for small leisure ship boats. A proper range for design parameters has to be set by the user. An optimization based on the Particle Swarm Optimization algorithm is carried out to minimize a fitness function representing the engine’s fuel consumption. The OpenProp code has been integrated in the procedure to compute thrust and torque. Blade’s geometry and tables about pitch, thrust and consumption are the main output of the optimization process. A case study has been included to show how the procedure can be implemented in the design process. A case study shows that the procedure allows a designer to sketch a controllable pitch propeller with optimal efficiency; computational times are compatible with the design conceptual phase where several scenarios must be investigated to set the most suitable for the following detailed design. A drawback of this approach is given by the need for a quite skilled user in charge of defining the allowable ranges for design parameters, and the need for data about the engine and boat to be designed.

Keywords: CAD | Controllable pitch propeller | Design propeller | Particle swarm optimization

Abstract: A numerical investigation is conducted in order to identify a PID control loop feedback scheme able to return dynamics augmentation and superior seakeeping characteristics in the application of high speed flying yacht hulls. An existing lumped parameters model based on general unsteady equations of motion is extended and implemented in combination with a regular basic ocean waves model, to conduct parametric studies and predict the overall performances of a specific engine-propelled flying yacht hull, both in calm and rough water conditions. The unsteady behavior of six foiling/maneuvering appendages is investigated, the hydrodynamic characteristics being based on a database generated through the use of computational fluid dynamics methods (CFD) coupled with static/dynamic-mesh schemes. Equations of motion and hydrodynamics are solved numerically by explicit time-integration method. By comparison with control open-loop conditions, the results show the effects of the use of PID controllers in such dynamic systems in terms of seakeeping performances and dynamics augmentation.

Keywords: Flying yacht | Foiling | Hydrodynamic performances | Lumped parameters model | Ocean waves | PID control

Abstract: This study is focused on the development of longitudinal aerodynamic models for steady flight conditions. While several commercial solvers are available for this type of work, we seek to evaluate the accuracy of an open source software. This study aims to verify and demonstrate the accuracy of the OpenFoam solver when it is used on basic computers (32-64GB of RAM and eight cores). A new methodology was developed to show how an aerodynamic model of an aircraft could be designed using OpenFoam software. The mesh and the simulations were designed only using OpenFoam utilities, such as blockMesh, snappyHexMesh, simpleFoam and rhoSimpleFoam. For the methodology illustration, the process was applied to the Bombardier CRJ700 aircraft and simulations were performed for its flight envelope, up to M0.79. Forces and moments obtained with the OpenFoam model were compared with an accurate flight data source (level D flight simulator). Excellent results in data agreement were obtained with a maximum absolute error of 0.0026 for the drag coefficient, thus validating a high-fidelity aerodynamic model for the Bombardier CRJ-700 aircraft.

Keywords: Aerodynamics | Compressible flow | CRJ-700 aircraft | Incompressible flow | OpenFoam software

Abstract: Augmented Reality (AR) is worldwide recognized as one of the leading technologies of the 21st century and one of the pillars of the new industrial revolution envisaged by the Industry 4.0 international program. Several papers describe, in detail, specific applications of Augmented Reality developed to test its potentiality in a variety of fields. However, there is a lack of sources detailing the current limits of this technology in the event of its introduction in a real working environment where everyday tasks could be carried out by operators using an AR-based approach. A literature analysis to detect AR strength and weakness has been carried out, and a set of case studies has been implemented by authors to find the limits of current AR technologies in industrial applications outside the laboratory-protected environment. The outcome of this paper is that, even though Augmented Reality is a well-consolidated computer graphic technique in research applications, several improvements both from a software and hardware point of view should be introduced before its introduction in industrial operations. The originality of this paper lies in the detection of guidelines to improve the Augmented Reality potentialities in factories and industries.

Keywords: augmented reality | design for disassembly | factory automation | Industry 4.0 | maintenance | mixed reality | object tracking

Abstract: The aim of this paper is to describe the application of digital visualization tools to assist air accident investigators, including both their investigation activities and as a training resource. Augmented Reality technology is used to re-create a real aircraft crash scene, both in terms of wreckage distribution and features of the surroundings, in a full-scale 3D representation. A case study shows both potentials and limitations of the approach, and recommendations on how to improve the methodology are also proposed. Overall, it is concluded that Augmented Reality has achieved a maturity stage sufficient to consider it as an effective tool for training of air accident investigators and, to some extent, to support the investigation process itself, although more developments are required to address some current limitations and fully exploit the capabilities of this technology.

Keywords: Augmented Reality | Aviation accident investigations | Aviation safety

Abstract: Smoothing algorithms are used for mesh refinement and to remove undesired surface. This numerical procedure is recommended and applied on triangulated file coming from 3D scanners or Topology optimization designs based on voxel representation before the optimized structure is manufactured by Additive Manufacturing technologies. In literature, there are several available algorithms, but many of them suffer from mesh shrinkage and do not give to the designer easy procedures to select regions which do not need the application of the smoothing procedure as holes or flat surfaces. For this reason, an improved vertex-based algorithm is presented in this work along with a case study to prove its performances compared with existent algorithms. The algorithm confirms to be efficient and useful. However, user's intervention is required to guide the procedure to get proper results.

Keywords: mesh fairing | mesh smoothing | topology optimization | voxel

Abstract: Purpose: The purpose of this study is the evaluation of advantages and criticalities related to the application of addtive manufacturing (AM) to the production of parts for musical instruments. A comparison between traditional manufacturing and AM based on different aspects is carried out. Design/methodology/approach: A set of mouthpieces produced through different AM techniques has been designed, manufactured and evaluated using an end-user satisfaction-oriented approach. A musician has been tasked to play the same classical music piece with different mouthpieces, and the sound has been recorded in a recording studio. The mouthpiece and sound characteristics have been evaluated in a structured methodology. Findings: The quality of the sound and comfort of 3D printed mouthpieces can be similar to the traditional ones provided that an accurate design and proper materials and technologies are adopted. When personalization and economic issues are considered, AM is superior to mouthpieces produced by traditional techniques. Research limitations/implications: In this research, a mouthpiece for trombone has been investigated. However, a wider analysis where several musical instruments and related parts are evaluated could provide more data. Practical implications: The production of mouthpieces with AM techniques is suggested owing to the advantages which can be tackled in terms of customization, manufacturing cost and time reduction. Originality/value: This research is carried out using a multidisciplinary approach where several data have been considered to evaluate the end user satisfaction of 3D printed mouthpieces.

Keywords: Additive manufacturing | Dental materials | Fused deposition modelling | Musical instruments | Stereolithography

Abstract: The interest of industrial companies for the Additive Manufacturing (AM) technology is growing year after year due to its capability of producing components with complex shapes that fit industrial engineering necessities better than traditionally manufactured parts. However, conventional Computer-Aided Design (CAD) software are often limited for the design and representation of complex geometries, especially when dealing with lattice structures: these are bio-inspired structures composed of repeated small elements, called struts, which are combined to shape a unit cell that is repeated across a domain. This design method generates a lightweight but stiff component. The scope of this work is to analyse the problem of the lattice structures representation in 2 D technical drawings and propose some contributions to support the development of Standards for their 2 D representation. This work is focused on the proposal of rules useful to represent such hierarchic structures. Python language and the open-source software FreeCad™ are used as a software platform to evaluate the suitability and usability of the proposed representation standard. This is based on simplified symbols to describe complex lattice structures instead of representing all the elements which constitute the lattice. The standard is thought to be used in technical 2 D drawings where assemblies are represented and lattice components are used (e.g. parts assembly, maintenance, parts catalogues). A case study is included to describe how the proposed standard could be integrated into a 2 D assembly drawing, following technical product documentation production typical workflow.

Keywords: Additive manufacturing | design | drawing standards | ISO standards | lattice structures

Abstract: Additive Manufacturing is becoming a suitable production process for many industries: it is based on the idea of adding material layer by layer, in opposite to traditional manufacturing processes. This technology shows advantages as design flexibility, internal logistics minimization and product customization that make it perfect to produce customized parts and all the applications where low production rates occur. The production of spare parts for classic or luxury cars is a field where Additive Manufacturing can be adopted because of low demand and relevant costs to manage stocks keeping several different parts in the after-sales inventory. The photogrammetry technique has been investigated to obtain the 3D model of the component to be replaced and send it to decentralized production centers equipped with 3D printers. This approach can enhance by far the supply chain management for automotive spare parts.

Keywords: Additive Manufacturing | Automotive | Maintenance | Photogrammetry | Supply chain management

Abstract: A significant growth of Additive Manufacturing technology has been noticed in the last few decades due to its well-established advantages. This production process based on the idea of adding material layer by layer, instead of removing it, has several advantages such as: time reduction in the design-to-manufacturing cycle, capability to produce complex shapes in a single piece thus reducing the connections, and weight saving just to mention the main significant. On the same wave of enthusiasm, the research community is significantly focused on this technology and many contributions that are focused on the whole range of aspects connected to this manufacturing way are already available. However, Additive Manufacturing is in a development phase, and the design tools, the material portfolio and the production methodologies are still far from the optimum typical of mature technologies. This paper critically reviews the Additive Manufacturing advantages and weaknesses which nowadays limits its wider application; a discussion about how these problems could be solved is included, together with an outlook of the challenges the practitioners must face off from nowadays up to a time window of ten years.

Keywords: Additive Manufacturing | Design tools | Future challenges | Technology review | Topological optimization

Abstract: This work describes a Mixed Reality application useful to modify and cut virtual objects. A digital simulation of surgical operations is presented. Following this approach, surgeons can test all the designed solutions of the preoperative stage in a Mixed Reality environment. High precision in surgery applications can be achieved thanks to the new methodology. The presented solution is hands free and does not need the use of a mouse or computer’s keyboard: it is based on HoloLens, Leap Motion device and Unity. A new cutting algorithm has been developed in order to handle multiple objects and speed up the cut with complex meshes and preserve geometry quality. A case study presents the cut of several bones in order to simulate surgeon’s operations. A reduction in cut time compared to the original method is noticed, together with a high flexibility of the tool and a good fidelity of the geometry. Moreover, all the object fragments generated from the algorithm are available for manipulation and new cuts.

Keywords: cutting algorithm | leap motion | Mixed Reality | unity

Abstract: The paper broadly addresses how Industry 4.0 program drivers will impact maintenance in aviation. Specifically, Industry 4.0 practices most suitable to aeronautical maintenance are selected, and a detailed exposure is provided. Advantages and open issues are widely discussed and case studies dealing with realistic scenarios are illustrated to support what has been proposed by authors. The attention has been oriented towards Augmented Reality and Additive Manufacturing technologies, which can support maintenance tasks and spare parts production, respectively. The intention is to demonstrate that Augmented Reality and Additive Manufacturing are viable tools in aviation maintenance, and while a strong effort is necessary to develop an appropriate regulatory framework, mandatory before the wide-spread introduction of these technologies in the aerospace systems maintenance process, there has been a great interest and pull from the industry sector.

Keywords: Additive Manufacturing | Aeronautical maintenance | Augmented Reality | Industry 4.0

Abstract: Aim of this paper is to present a methodology useful to optimize the geometry of the blades of a small-size wind turbine which are obtained from a circular pipe: an optimal chord distribution and airfoil sweep can be obtained with a proper cutting path. A strong reduction in manufacturing costs and time can be achieved for blades which are a critical element in wind turbine systems, especially in case of renewable plants in developing countries. An algorithm has been developed to obtain the shape of the blades and wind turbine performances are computed by the Blade-Element Method, due to its low computational simplicity; the XFoil tool has been used to compute the aerodynamic of the blades. Heuristic algorithms have been applied to obtain a feasible design solution assuring the best efficiency of the wind turbine. Also structural considerations are kept into account to provide a feasible configuration able to withstand the forces acting on the rotating blades. Results obtained suggest that an optimal design of such a kind of blades can be obtained thanks to this methodology. The mathematical framework developed for the optimization is efficient and the heuristics algorithms allow the convergence to feasible configurations. The computing time is compatible with a practical application of the method also in industries.

Keywords: CAD | Design | Multidisciplinary optimization | Particle swarm algorithm | Wind turbine

Abstract: The longitudinal compressive response of unidirectional high-stiffness carbon fibres radially confined with glass fibre and embedded in an epoxy matrix are analysed in this study. The method was originally developed for reinforced concrete columns. For this class of hybrid composites, initial fiber misalignment along with material nonlinearity leads to the initiation of fibre kinking. The load carrying capability is expected to be preserved due to the presence of lateral confinement. However, compressive strength is highly depended on fibre alignment. If, via manufacturing highly aligned fibres can be formed, then this could potentially lead to micro-buckling failure initiation.

Keywords: Compressive strength | Confinement | Fiber reinforced composite | Kink banding | Microbluckling | Progressive damage and failure

Abstract: Additive manufacturing (AM) is becoming an important alternative to traditional processes. AM technology shows several advantages in literature, and its use increases in aerospace, automotive and biomedicine. Time reduction in design-to-manufacturing cycle, customization, capability to generate complex shapes in one piece and ability to imitate low-weight bio-inspired shapes are the strength of designs based on AM. Due to its potentials, major progresses were done in AM, thanks to technology evolution and increased computational power. With regard to AM, voxelization can be defined as part's discretization in hexahedral elements, as done with pixels in 2D image. Voxels are used to speed-up geometry and algebraic manipulation thanks to their inherent advantages. This paper analyses advantages and criticalities of AM and voxel manipulation through a systematic literature review methodology. The analyses are based upon the filtering of a huge amount of publications available in literature up to obtaining the most significant 25 studies published in the last 5 years. The study's main result is the technology gap's identification, i.e. where AM and voxelization still need improvements, thus providing the reader with suggestions about possible further studies. Computer elaboration power and voxel discretization algorithms are suggested being key issues in AM's further development.

Keywords: Additive manufacturing | Design | Systematic literature review (SLR) | Voxel

Abstract: This paper describes the application of a novel virtual prototyping methodology to wind turbine blade design. Numeric modelling data and experimental data about turbine blade geometry and structural/dynamical behaviour are combined to obtain an affordable digital twin model useful in reducing the undesirable uncertainties during the entire turbine lifecycle. Moreover, this model can be used to track and predict blade structural changes, due for example to structural damage, and to assess its remaining life. A new interactive and recursive process is proposed. It includes CAD geometry generation and finite element analyses, combined with experimental data gathered from the structural testing of a new generation wind turbine blade. The goal of the research is to show how the unique features of a complex wind turbine blade are considered in the virtual model updating process, fully exploiting the computational capabilities available to the designer in modern engineering. A composite Sandia National Laboratories Blade System Design Study (BSDS) turbine blade is used to exemplify the proposed process. Static, modal and fatigue experimental testing are conducted at Clarkson University Blade Test Facility. A digital model was created and updated to conform to all the information available from experimental testing. When an updated virtual digital model is available the performance of the blade during operation can be assessed with higher confidence.

Keywords: Composite materials | Design | Digital twin | Finite element method | Modelling and simulation | Wind turbine

Abstract: This paper presents a knowledge based engineering environment methodology to support the designer in the correct setting of geometrical and dimensional tolerances in assemblies of mechanical components. The procedure is based on the definition of the functional requirements needed to allow the proper working of the assembly; in the further, a software tool is used to do a statistical analysis of the assembly relations, providing an estimation of the components waste due to poor compliance to the tolerances. A case study given by the design of a marine power transmission is presented: the methodology leads to the change of some tolerances to improve the design by reducing the number of waste components. The strength of the methodology is represented by the fact it can help unskilled designers in the correct setting of tolerances in drawings.

Keywords: CAD | CAT | design | GD&T | power transmission

Abstract: An impulsive thruster propulsion system that could be used in a multi-modal UAV capable of sustained aerial flight, locomotion in water and deployment from a tube filled with compressed air is under development. This paper covers the design and optimisation process of the propulsive system, as well as its modelling with analytical and CFD simulations to predict the performances. The system is designed to fulfil vehicle mission requirements in terms of altitude and velocity after water/air transition. The thruster uses a common CO2 cartridge available off-the-shelf to accelerate water stored inside a water chamber along with an inflator to activate and regulate the mechanism remotely for efficient and sustained thrust. Water is chosen as vectorial fluid since it is available from the surroundings. Water chamber sizing process uses an analytical model calibration through CFD approach to refine an analytical model and predict propulsion performances. After thruster sizing, an experimental prototype was fabricated and tested for model validation. A comparison and discussion of the results as future work is also proposed with areas for improvement and development.

Abstract: A new composite material, defined as Ductile High Energy Composite (DHEC), is analysed in this paper, with particular reference to the energy absorbed after high speed impacts and to the relevant failure mode. A set of DHEC and pure carbon fibre laminates presenting equal weight, equal bending strength or equal stiffness, respectively, have been compared measuring the energy absorbed after the impact of a bullet, through the difference between the total energy of the bullet and the one corresponding to its penetration in a wooden block after hitting the specimens. Fracture modes have been investigated using an optical microscope. Energy absorbed by DHEC laminates is of the same order than for pure carbon ones; however, the DHEC failure mode (referred to as “petaling”) presents a lower spreading of splinters respect to the pure carbon fibres (brittle fracture) case. Even though a wider testing campaign is necessary to better evaluate the DHEC properties, they appear to be suitable for adoption in all those applications where impacts can be harmful for end-users or people. Further research on high energy absorption properties is needed to better characterize these innovative composite materials, yet the outcome of this study suggests the high potential of DHEC.

Abstract: Modern engineering requires finding an optimal trade-off point among conflicting requirements that must be satisfied to reach the end user's satisfaction. One of the most challenging problems in multidisciplinary optimization is to find a fitness function that can best translate what the designer really aims to obtain. In this paper, a particle swarm optimization (PSO) algorithm is coupled to a fitness function based on the definition of a technique for order preference by similarity to ideal solution (TOPSIS) in order to obtain a new algorithm called PSOTOP. The fitness of a candidate solution is found by comparing its attributes to those of an “ideal best” and “ideal worst” solution, which is dynamically updated at each iteration of the algorithm. The advantage of this solution is that the fitness allows combining attributes of different magnitude and measurement units in an effective way; this approach can be applied to whatsoever optimization problem in engineering, economics, medicine, and statistics. This paper presents a case study dealing with the optimal design of an airfoil to be adopted on the wing of an unmanned air vehicle to support civil protection operations in order to show how this strategy can impact the design of a complex product. The main limitation of this approach relates to the fact that the user must possess a good knowledge of the specific problem to be solved in order to set proper ranges for design parameters and attributes' weight in the fitness evaluation.

Keywords: Bézier curves | design | engineering optimization | particle swarm optimization | TOPSIS

Abstract: The present work proposes a new approach for defining an interactive user manual in complex assemblies, using a new enabling technology of Industry 4.0, i.e. Augmented Reality. The AR environment supports the user in step-by-step assembly on-the-fly. The study of this method, suitable for the assembly of parts, is a stimulating engineering mission, which takes advantage of the latest innovations in imaging technologies and computer graphics. In the present paper, a proposal for an innovative method based on Augmented Reality used to support the components’ assembly is suggested. The methodology is based on a four steps process: (1) the designer performs the assembly structure through a CAD system; (2) an inexperienced user assembles the same parts without any suggestion, and the differences between the two assembly sequences are documented and broken down in order to distinguish critical points in the assembly; (3) a virtual user manual is shaped in an Augmented Reality environment; and (4) the assembly is then performed by the same inexperienced user, guided by the AR tool. When the end-user employs the instrument, the location of the item to assemble is perceived by tracking the finger position of the user itself. In order to help the end-user in the assembly procedure, a series of symbols and texts is added to the external scene. In this paper, a case study based on the assembly of a scale model has been developed to evaluate the methodology. After an evaluation process, the procedure seems to be feasible and presents some advantages over the state-of-the-art methodologies proposed by literature.

Keywords: Assembly | Augmented Reality | Marker | Task automation | User manual

Abstract: A multi-modal UAV capable of sustained aerial flight, locomotion in water and deployment from a tube filled with compressed air is under development. This paper covers the design and integration process of a CO 2 thruster previously designed in a vehicle designed to fulfil mission requirements in terms of altitude and velocity after water/air transition. The thruster uses a common CO 2 cartridge available off-the-shelf to accelerate water stored inside a water chamber for efficient and sustained thrust. Water is chosen as vectorial fluid since it is available from the surroundings. Analytical model, described in the paper, evaluates water to air transition phase in terms of trajectory, reached altitude and velocity. After thruster performances evaluation thanks to the analytical model, an experimental prototype was fabricated and tested for model validation. High speed camera is used to track vehicle transition and Kinovea software exports resulting data from a recorded video to spreadsheet formats for scientific study and post-processing. A comparison and discussion of the results as future work is also proposed with areas for improvement and development.

Keywords: Bimodal vehicle | Bio-inspired vehicle | Testing | Transition | Unmanned vehicle

Abstract: The paper discusses how Industry 4.0 could impact practitioners performing maintenance in aviation. The attention has been on Augmented Reality and Additive Manufacturing, which can support maintenance tasks and spare parts production respectively. Advantages and open issues are widely discussed and couple of case studies dealing with realistic scenarios are presented to support what has been proposed by the authors. The intention is to demonstrate that AR and AM are viable tools in aviation maintenance, even if effort is necessary to develop an appropriate regulatory framework, required before the introduction of these technologies in the maintenance process. Once applied to real maintenance tasks by airline companies, the practitioning community can develop best practices and the necessary regulation pertaining to maintenance and repair of aerospace systems using AR and AM technologies.

Keywords: Additive Manufacturing | Aeronautical Maintenance | Augmented Reality | Industry 4.0

Abstract: This paper describes the implementation of a framework which can be used to optimize the external shape of an unconventional airship configuration. This framework includes the estimation of Added Masses (AM) which captures the contribution of the dynamic effect related to the acceleration of a body immersed in a fluid having a similar density to that of the body itself. A computationally efficient routine to compute AM has been implemented in a heuristic optimization loop based on a Particle Swarm Optimization (PSO) algorithm, and has been integrated into a simple model which provides hybrid airship's aerodynamics characteristics. As a case study, the take-off distance of a hybrid airship has been optimized by the methodology, and it is used to show the effect on the optimization loop and the errors arising from using conventional approximated AM evaluation methods. The proposed set of simulations clearly evaluates the errors expected on the unconventional airships performances when approximated methods are used in the evaluation of the AM.

Keywords: Added masses | Airships | Conceptual design | Multidisciplinary optimization | Particle Swarm Optimization

Abstract: This paper describes the beneficial impact of an augmented reality based technique on the 3D printing process monitoring within additive manufacturing machines. A marker is applied in a fixed point of the rapid prototyping machine, integral with the component being manufactured; as an alternative, a markerless approach can be followed too. A virtual model of the object to be printed is superimposed to the real one. In this way, the shape of the object in different printing stages can be viewed. An interactive comparison between real and virtual model can be carried out both in manual and automatic mode. If manufacturing errors are detected, the building process can be stopped. Augmented reality technique allows an intuitive shape check of a part being printed with rapid prototyping technologies. In case of complex objects it helps the operator in the detection of possible errors along the manufacturing process; stopping the machine as soon as an error appears avoids waste of machining time and material. The average precision of the augmented reality is useful to find significant geometrical errors; geometrical deviations less than 1 mm can hardly be assessed both in manual and in automatic mode, and further studies should be carried out to increase the technique precision and range of application. To the best of the authors’ knowledge it is the first time where experiments on the integration between augmented reality and rapid prototyping to interactively monitor 3D parts’ printing have been investigated and reported in literature.

Keywords: 3D printing | Additive Manufacturing | Augmented Reality | Design | Rapid Prototyping

Abstract: This paper presents the determination of the vibration impact of the helicopter structural components and skin repairs in terms of frequency characteristics. To address this issue, a 3D Finite Element Method (FEM) model of 349 Gazelle helicopter has been developed in ABAQUS and the frequency analysis is conducted. The results on the natural frequencies of the full structure reasonably match with the literature giving confidence in the baseline model. The main advantage of this FEM model is that, it can be used to predict the natural frequencies of the full structure, precisely. In addition, the material properties and conditions of the components can be updated based on the applied conditions during the repair and maintenance period. Thus, the model gives a comprehensive design tool for analysing the frequencies of the helicopter with differing components. The effective variations in the frequency changes due to repair are predicted numerically. The discussion of these results helps in developing leads to improved selection of replacement materials and their properties.

Abstract: This research focuses on the integrated simulation of helicopter-pilot system to predict pilot's physiological and psychological responses to the vibration. This paper describes the approach of integration of helicopter structural model to the aerodynamic forcing function and to the pilot-seat model. The physiological and psychological responses at 5 Hz are calculated based on vibration transmission ratio of the pilot's body segments. The pilot's Physiological responses including heart rate, highest blood pressure, lowest blood pressure, respiration rate and saliva secretion quantity are presented. Tired eyes, irritation, dizziness, yawning, sleepiness and headache as psychological reactions are provided. The integrated simulation approach of helicopter-pilot system can be used for pilot health and comfort assessments, helicopter structural and cockpit and seat design.

Abstract: The associated risk for a patient taking advantage of Helicopter Emergency Medical Services (HEMS) mainly relates to vibrations. To this aim, especially in case of trauma and serious illness and long travels, aspects related to the vibrations effects on the patient needs to be properly investigated, taking into account the particular features of the helicopter used for HEMS. The purpose of this paper is the integrated simulation of vertical vibration at the supine patient’s body, lying down on a rescue litter, in HEMS. Here, a 3D structural model of a reference helicopter, the Aerospatiale Gazelle, has been developed in ABAQUS and integrated with a dynamic model where aerodynamic forcing functions due to rotor are modelled. The accelerations at the litter location in the helicopter structural model are recorded and used as inputs to the supine patient’s body model in MATLAB. The Multi-Body (MB) model of the patient’s body consists of three interconnected masses of the head-neck, torso-arms and pelvis-legs. The simulation is carried out for single manoeuvre and the vibration information is extracted at the three body segments. This predictive approach of integrated simulation of the helicopter-patient is an effective tool in investigating of biodynamic response of the patient in HEMS. The benefits of this approach are reducing the risk and costs of running the experiments, providing suggestions on redesigning of litters and controlling the vibration on the litters in HEMS.

Keywords: Helicopter Emergency Medical Service | HEMS | Simulation | Structural model | Supine patient’s body | Vertical vibration

Abstract: This paper describes the features of AMCOMP, a CAD environment conceived to manage the computation of the Added Masses of bodies moving in an infinite fluid. A methodology already published in literature has been implemented in a CAD environment and its features are exploited to perform the evaluation of the Added Masses. These include the importing of the model in STL file format and the computation of the complete Added Mass matrix and non-dimensional terms. The CAD has been validated by computing the Added Masses values of bodies whose exact formulation was found in literature. The validated tool has been applied to more complex case studies where the Added Masses values were guessed using empirical laws or the equivalent ellipsoid approximation. Significant differences have been found between approximated methods and computations on real shapes. It is shown that the precision in the Added Masses computation and the computational time depend on the meshing quality of the model and power of the PC on which the software runs. Several tools have been merged to obtain a model useful for the Added Masses computation and to assess the errors arising from using approximated formulas instead of the real shape of the body.

Keywords: Added Masses | Computer Aided Design | Conceptual design | User interface

Abstract: The mounting attention to environmental issues requires adopting better disassembly procedures at the product's End of Life. Planning and reckoning different disassembly strategies in the early stage of the design process can improve the development of sustainable products with an easy dismissing and recycling oriented approach. Nowadays many Computer Aided Process Planning software packages provide optimized assembly or disassembly sequences, but they are mainly based on a time and cost compression approach, neglecting the human factor. The environment we developed is based upon the integration of a CAD, an Augmented Reality tool, a Leap Motion Controller device, see-through glasses and an algorithm for disassembly strategies evaluation: this approach guarantees a more effective interaction with the 3D real and virtual assembly than an approach relying only on a CAD based disassembly sequence planning. In such a way, the operator may not test in a more natural and intuitive way automatic disassembly sequences, but he/she can also propose different strategies to improve the ergonomics. The methodology has been tested in a real case study to evaluate the strength points and criticalities of this approach.

Keywords: Augmented Reality | CAD | Design for Disassembly | Disassembly Sequence Optimization

Abstract: The study of the methodologies useful to support the assembly of parts is a challenging engineering task which can benefit of the most recent innovations in computer graphics and visualization technologies. This paper presents a proposal for an innovative methodology based on Virtual and Augmented Reality useful to support the components’ assembly. The herein introduced strategy is based upon a four stages procedure: at first the designer conceives the assembly sequence using a CAD system, visualizing the scene wearing an immersive Virtual Reality device. In the second stage, the same sequence is developed by an unexperienced user using the same equipment: the differences between two assembly sequences are recorded and exploited to detect critical points in the assembly sequence and to develop a Knowledge Based System. Finally, a virtual user manual is produced in Augmented Reality. When the final user uses the tool, the position of the object to assemble is detected by tracking the finger position of the user itself. A series of symbols and writings is added to the external scene to help the end-user in the assembly procedure. A test case based on the assembly of a scale model has been developed to evaluate the methodology. After an evaluation process, the procedure seems to be feasible and presents some advantages over the state-of-the-art methodologies proposed by literature.

Keywords: Assembly | Augmented Reality | Marker | Task automation | Virtual Reality

Abstract: This paper presents the development of a CAD conceived to support the modelling of lightweight and lattice structures just from the initial stages of the design process. A new environment, called LWSM (acronym of LightWeight Structures Modelling), has been implemented in Python programming language in an open-source CAD software to allow the fast modelling of several sandwich structures or the filling of solid parts with cubic and tetrahedral lattice structures which can be produced by Additive Manufacturing (AM) techniques. Several tests have been carried out to validate the tool, one of which is included in the paper. The design of a bracket component inside LWSM using a traditional dense geometry and a lattice structure is described. The use of Design for Additive Manufacturing (DfAM) functions helps the user in the design of innovative structures which can produced only with AM technologies. A significant change in the shape of the part respect to traditional solutions is noticed after the use of DfAM functions by experimenters: FEM analysis confirms a strong weight reduction.

Keywords: Additive manufacturing | CAD | FEM analysis | Lattice structure | Lightweight structures

Abstract: Purpose - This paper aims to describe a methodology to optimize the trajectory of unconventional airship performing a high-altitude docking manoeuvre. Design/methodology/approach - The trajectories are based upon Bezier curves whose control points positions are optimized through particle swarm optimization algorithm. A minimum energy strategy is implemented by considering the airship physical properties. The paper describes the mathematical model of the airships, the trajectories modelling through Bezier's curves and the optimization framework. A series of test cases has been developed to evaluate the proposed methodology. Findings - Results obtained show that the implemented procedure is able to optimize the airship trajectories and to support their in-flight docking; a strong influence of the wind speed and course on the trajectories planning is highlighted. Research limitations/implications - The wind speed considered in these simulations depends only on altitude, and gusts effect has been neglected. Practical implications - The proposed model can support the study of unconventional airship trajectories and can be useful to evaluate best in-air docking strategies. Originality/value - The paper addresses the problem of trajectory optimization for a class of new air vehicles with an heuristic approach.

Keywords: Airship | Bezier curves | Green transportation | Heuristic algorithms | Trajectories optimization

Abstract: This paper describes a handheld application to help pilots when entering degraded visibility conditions. In this case, the loss of control is a typical emergency situation from which a pilot should be able to recover, but often he/she doesn’t do owing to problems of situation awareness. A new instrument, based on the use of accelerometers/GPS equipping modern handheld devices has been designed, virtually tested in flight simulators and finally tested in flight. Attention has been given to show essential information in a very simple and intuitive way, so that the instrument can be useful in case of pilot disorientation, panic or high stress levels. After a testing phase, the instrument showed useful to provide an indication about the attitude of the plane and to provide the pilot an indication of the stick and throttle movements needed to restore a safe levelled flight. The use of this application by pilots in emergency situation can enhance the survivability in Instrument Meteorological Conditions also without a specific training. This paper shows how the high computation capability and advanced visualization devices typical of smartphones can be useful to increase the flight safety by developing a new class of emergency not-certified instruments. A further testing phase of the instrument in critical conditions like gusty environment or deteriorated weather will be carried out as a future development of this work to better evaluate the limits of the instrument herein described.

Keywords: Flight safety | Flight simulation | Human machine interfaces | IMC | VMC

Abstract: A novel Augmented Reality (AR) tool for structural health monitoring is illustrated in this work. It provides maintenance operators with the results of an impact detection methodology. It interacts with an eyepiece allowing the inspector to see the estimated impact position on the structure. Electric signals are collected by a network of piezosensors bonded on the structure to be monitored. Dispersive propagation compensation is performed to improve estimation robustness. Hyperbolic beamforming is exploited to locate the impact. Real-time impact data are finally fed to the AR eyepiece. The proposed approach is tested on a Cessna 150 engine cowling. Experimental results confirm the feasibility of the method and its exploitability in maintenance practice.

Keywords: Augmented reality | Guided waves | Structural health monitoring

Abstract: The maturity reached in the development of Unmanned Air Vehicles (UAVs) systems is making them more and more attractive for a vast number of civil missions. Clearly, the introduction of UAVs in the civil airspace requiring practical and effective regulation is one of the most critical issues being currently discussed. As several civil air authorities report in their regulations "Sense and Avoid" or "Detect and Avoid" capabilities are critical to the successful integration of UAV into the civil airspace. One possible approach to achieve this capability, specifically for operations beyond the Line-of-Sight, would be to equip air vehicles with a vision-based system using cameras to monitor the surrounding air space and to classify other air vehicles flying in close proximity. This paper presents an image-based application for the supervised classification of air vehicles. First, several vehicle images, taken from different points of view, are transformed using a descriptor of salient features as to build the five-class database used to train the classification algorithm. Then, the latter compares the descriptor of a vehicle image taken from a random point of view to records in the database. With a positive match, the vehicle will be assigned to one of the following classes: a) civil transport aircrafts, b) military aircrafts, c) general aviation aircrafts, d) helicopters, and e) airships/hot air balloons. The paper provides a possible layout for the algorithm implementation and presents the outcome of several tests performed to evaluate its efficiency and possible exploitation. Indications useful to further studies are presented to help future researches.

Abstract: The high number of hull losses is a main concern in the UAV field, mostly due to the high cost of on-board equipment. A crashworthiness design can be helpful to control the extent and position of crash impact damage, minimizing equipment losses. However, the wide use of composite materials has recently put the accent on the lack of data about the behavior of these structures under operative loads, such as the crash conditions. This paper presents the outcome of a set of tests carried out to achieve a controlled crush of UAV structures, and to maximize the Specific Energy Absorption. In this work, a small-scale experimental test able to characterize the energy absorption of a Carbon-fiber-reinforced polymer under compression was developed introducing self-supporting sinusoidal shape specimens, which avoid the need for complex anti-buckling devices. The specimens were produced with different auto-triggering configurations and fibers' continuity was interrupted in selected position and for different extent in order to investigate the Specific Energy Absorption of the weakened laminates. The auto-triggering configuration was able to control the position of the initial failure of the specimen without any decrease in safety performance. This new kind of very light crash absorber can be used in small UAV to reduce the crash loads in the avionic and payload bay. With reference to a small UAV designed and manufactured at University of Bologna, an optimization of the crash absorbers positions has been carried out in order to achieve the best results in terms of energy dissipation.

Abstract: Traditional User/Maintenance Manuals provide useful information when dealing with simple machines. However, when dealing with complex systems of systems and highly miniaturized technologies, like UAVs, or with machines with millions of parts, a commercial aircraft is a case in point, new technologies taking advantage of Augmented Reality can rapidly and effectively support the maintenance operations. This paper presents a User/Maintenance Manual based on Augmented Reality to help the operator in the detection of parts and in the sequence to be followed to assemble/disassemble systems and subsystems. The proposed system includes a handheld device and/or an head mounted display or special goggles, to be used by on-site operators, with software management providing data fusion and overlaying traditional 2D user/maintenance manual information with an augmented reality software and appropriate interface. This device is connected by internet to a maintenance centre located in the aircraft manufacturer facilities. The on-site operator can directly access to multimedia content and historical information and can be helped or guided remotely by expert engineers residing at the manufacturer company offices. This resource may exploit Computer Aided Design and Product Data Management PDM remote facilities to prepare additional and specific 3D graphic content, supported also by a video and audio streaming from the camera and microphone of the on-site operator's handheld device. The proposed solution has revealed a number of significant advantages compared to the currently used operations: there is no need for preparing animations and graphic content for all the required maintenance sequences. The expert engineers and designers can both be involved directly in the maintenance tasks, a useful mean of feedback to evaluate the design for further projects or for project improvement. Additionally, the sensitive data is not shared outside the company since data is transmitted for visual display but it is stored on a secured location.

Abstract: The flight simulation of airships and hot air balloons usually considers the envelope geometry as a fixed shape, whose volume is eventually reduced by ballonets. However, the dynamic pressure or helium leaks in airships, and the release of air to allow descent in hot air balloons can significantly change the shape of the envelope leading to potential dangerous situations. In fact, in case of semi-rigid and non-rigid airships a reduction in envelope internal pressure can reduce the envelope bending stiffness leading to the loss of the typical axial-symmetric shape. For hot air balloons thing goes even worse since the lost of internal pressure can lead to the collapsing of the balloon shape to a sort of vertically stretched geometry (similar to a torch) which is not able to sustain the attached basket and its payload. These effect should be considered in simulations, however to compute in real time the envelope shape with Finite Element Methods is a complex and demanding task due to the high deformations, complex fabric model, and wrinkling effects. A possible solution to overcome this problem is to apply a Cloth Simulation Technique (CST) to the prediction of the envelope behaviour. This paper describes how such a model can be implemented for airship envelops and hot air balloons shape predictions. Appropriate algorithms have been developed in Matlab® and validation test have been conducted. Results show that this model can provide qualitatively good results, in agreement with the experience and the physics of the problem.

Abstract: The aim of this paper is to develop a new concept of unconventional airship based on morphing a lenticular shape while preserving the volumetric dimension. Lenticular shape is known to have relatively poor aerodynamic characteristics. It is also well known to have poor static and dynamic stability after the certain critical speed. The new shape presented in this paper is obtained by extending one and reducing the other direction of the original lenticular shape. The volume is kept constant through the morphing process. To improve the airship performance, four steps of morphing, starting from the lenticular shape, were obtained and compared in terms of aerodynamic characteristics, including drag, lift and pitching moment, and stability characteristics for two different operational scenarios. The comparison of the stability was carried out based on necessary deflection angle of the part of tail surface. The comparison results indicated that new shape concept possesses much better aerodynamic and stability characteristics and could be used for detailed optimisation studies.

Abstract: Carotid artery phantoms (CaPs) can be used as test objects to explore novel ways of enhancing the ultrasound based carotid atherosclerosis diagnosis. To achieve this goal CaPs should be anatomically realistic both in terms of geometry, acoustic and physical properties, and should allow to reproduce different pathological conditions. We propose a framework for designing CaPs of healthy and diseased arteries. To verify the framework effectiveness we constructed three CaPs: healthy, with a hard/soft plaque causing a 30%/65% vessel narrowing. Then we acquired CaPs B-mode images and performed their geometric characterization and echogenicity analysis demonstrating the framework effectiveness at realizing anthropomorphic CaPs at low cost, easily reproducing different atherosclerotic conditions.

Abstract: Wind tunnel experiments are performed to investigate the aerodynamic characteristics of unconventional airships docking in-flight. The aim is to provide wind tunnel data for multiple feeders docking to a cruiser and to identify key issues in docking approach strategies. The conceptual design of a docking mechanism and its integration into a baseline configuration is also addressed. Force and moment data are collected on a 1:7.5×10-4 scale model for the cruiser configurations and at various cruiser-feeder vertical separation distances to simulate docking. Results indicate that the there is a trade-off between drag performance and the implementation of the docking mechanism. Drag decrease is measured when the modified cruiser is docked with the feeders. Best docking practices are also identified from the pitching moment coefficients showing that the cruiser-feeder can be trimmed during docking.

Abstract: This paper presents a conceptual design of a satellite device to be used for capturing asteroids, based on inflatable structures. The mission requirements, the conceptual design, the methodology for the selection of the best solution, and simulations for the preliminarily structural analysis of the device are described within. Several finite element analyses have been carried out in order to find the best strategy to model flexible materials under internal pressure, and the device structure has been changed accordingly in order to obtain the best trade-off between weight and strength. This paper presents the sizing and the weight breakdown of the satellite inflatable components, which are quite complex to model with regards to the structural simulation. The results obtained seem to confirm the feasibility of such a structure and motivates further studies and experimental tests.

Keywords: Conceptual design | Fabric | FEM | Inflatable structure | MADM | α damping

Abstract: This paper describes the multidisciplinary optimization of an airship with unconventional configuration. The shape of the airship is based upon two semi-ellipsoids, whose axis ratios can be altered for optimization purpose. The parameters to optimize are volume, ratio between longitudinal and lateral semi-axis, ratio between vertical and lateral semi-axis, percentage of the top surface covered by photovoltaic films, and dimension of the tail. The objective of the optimization is to reduce the mass of the airship by keeping the equilibrium between buoyancy and weight as a constraint, reaching the design speed while maintaining the static longitudinal stability of the vehicle. The mathematical model developed to evaluate airship features includes the computation of the ballonet volume, a weight breakdown, considerations about the energy storage for night operations, the power system, and the stability. Six heuristic optimization strategies have been applied to achieve the best solution; some case studies have been developed, and the final optimal configurations found by algorithms have been analyzed to validate the optimization framework. The approach demonstrates that the heuristic optimization strategies used are good tools for the conceptual design of unconventional airship since this problem requires a multidisciplinary approach and several parameters including aerodynamics, propulsion, mass breakdown, aerostatics, and stability. These parameters are strongly dependent on each other and they must be considered together to obtain an optimum and balanced design.

Abstract: This paper presents a novel design methodology to be used in the evaluation of the main features of advanced unconventional airship configuration. Similar to the process used in aircraft design, the concept of volume fractions (VF) is introduced to estimate airship weights, dimensions, and performances, in an early design phase. The paper presents the complete methodology, with tables and constants to help unconventional airship designers with preliminary design considerations. Volumes and weights of candidate solutions are obtained through an iterative method within a user-friendly tool requiring graphical and straightforward mathematical operations. The solutions are ranked based on procedures aiming at satisfying customer needs and expectations provided as inputs. A case study highlighting a step-by-step methodology process is presented, and the approach followed to select the final solution is documented. The method is easy to use and implement, rapidly providing a significant amount of data. A parametric approach is used such that the evolution in materials and technology, new configurations, and modern power and energetic solutions can be considered by simply performing a parameter sweep to perform sensitivity analysis.

Keywords: Airship design and sizing | Conceptual design | Conventional and unconventional airships | Design synthesis

Abstract: Class-A curves show very appreciable features in terms of smoothness and curvature trend that is commonly perceived as high quality profiles. These curves are commonly sketched by experienced operators, but at the present day no tools are available to transform a B-spline into a Class-A curve. The k-neigh-fast is an improved version of k-neighbours algorithm, described in Amati et al. (Comput Graph 30(3):345-352, 2006), aiming to transform a B-spline non-Class-A slope into a B-spline Class-A curve by manipulating a group of k geometric coefficients. Once the level of detail (LOD) representation of a curve has been computed, the k-neigh-fast algorithm, detects those control points representing non-Class-A imperfections. At each LOD, the algorithm individuates the detail coefficient maximizing the internal functional. Then k-neighbours has been modified applying filtering criteria. A control step starts to verify the transformation from a non-Class-A curve into a Class-A shape. This process is repeated until the chosen stopping condition is satisfied. The final shape with improved smoothness and monotonic curvature is achieved through manual procedure. This paper reports results dealing on an improved and faster wavelet-based LOD filtering implementation used to generate very smooth set of profiles that own to Class-A set. The LODs representation allows to divide curves into their coarser least-square approximations and details coefficients. The extraction and manipulation of details with multi-level filtering, allows to determine geometric imperfections. This method has been tested to the smoothing of the hull profile of ships: results are good since the non-A-curve are well converted in smoother lines. A more efficient implementation, based on a flexible LOD representation led to prove many benefits of this techniques; the tests performed exploiting a computer program implementation have demonstrated very good results in most of simulations considered. © 2012 Springer-Verlag France.

Keywords: CAD | Class-A curves | Design | Smoothing optimization | Wavelets

Abstract: The space debris represents a danger for operative satellites and human missions. A large amount of debris is located in Low Earth Orbit and in Geostationary Orbit. The worldwide surveillance networks, mainly NORAD and RosKosmos, started monitoring debris since a long a time and testify the continuous growing tendency in the number of objects. Since a few years Aerospace Systems Laboratory of University of Rome started optical space debris observation campaigns by dedicated observatories. The observation activity includes not only planning and taking images of selected portions of the sky, but also analysis of raw picture data to extract the relevant astrometry and/or light-curve information. During the optical campaigns a large amount of images is typically taken and one of the most time consuming activities in optical space objects observation is the data analysis, requiring dedicated and specialized man power. This is the reason why the development of automatic images processing algorithms and procedures to identify the presence of debris, to identify its nature and perform the astrometry computations would highly desirable. This paper deals with the development of automatic procedures and algorithms to detect objects with relative motion with respect to stars in both sidereal tracking mode or terrestrial fixed one. In particular, the developed software is able to recognize the debris inside the picture, solve the star field within the picture and use both these information to achieve the angular measurements of the debris. Relevant efforts have been devoted to software development, such that human interaction is not required. The astrometry computations algorithm works without predefined information about the image. In particular the knowledge of the pointing angles are not required, even if starting from a condition close to the actual one improved the convergence speed, and the picture can be solved starting from a "lost in space" condition. The main algorithm drivers and the tradeoffs in the software implementation are depicted and preliminary results and software performance in actual observation campaigns are discussed in the paper.

Abstract: The modern development in design of airships and aerostats has led to unconventional configurations quite different from the classical ellipsoidal and spherical ones. This new class of air-vehicles presents a mass-to-volume ratio that can be considered very similar to the density of the fluid displaced by the vehicle itself, and as a consequence, modeling and simulation should consider the added masses in the equations of motion. The concept of added masses deals with the inertia added to a system, since an accelerating or decelerating body moving into a fluid displaces a volume of the neighboring fluid. The aim of this paper is to provide designers with the added masses matrix for more than twenty Lighter Than Air vehicles with unconventional shapes. Starting from a CAD model of a given shape, by applying a panel-like method, its external surface is properly meshed, using triangular elements. The methodology has been validated by comparing results obtained with data available in literature for a known benchmark shape, and the inaccuracies of predictions agree with the typical precision required in conceptual design. For each configuration, a CAD model and a related added masses matrix are provided, with the purpose of assisting the practitioner in the design and flight simulation of modern airships and scientific balloons.

Keywords: Added Masses | Aerostats | Airships | Lighter Than Air Vehicles | Panel Method

Abstract: The space debris is a challenging problem for the human activity in the space. Observation campaigns are conducted around the globe to detect and track uncontrolled space objects. One of the main problems in optical observation is obtaining useful information about the debris dynamical state by the images collected. For orbit determination, the most relevant information embedded in optical observation is the precise angular position, which can be evaluated by astrometry procedures, comparing the stars inside the image with star catalogs. This is typically a time consuming process, if done by a human operator, which makes this task impractical when dealing with large amounts of data, in the order of thousands images per night, generated by routinely conducted observations. An automated procedure is investigated in this paper that is capable to recognize the debris track inside a picture, calculate the celestial coordinates of the image's center and use these information to compute the debris angular position in the sky. This procedure has been implemented in a software code, that does not require human interaction and works without any supplemental information besides the image itself, detecting space objects and solving for their angular position without a priori information. The algorithm for object detection was developed inside the research team. For the star field computation, the software code astrometry.net was used and released under GPL v2 license. The complete procedure was validated by an extensive testing, using the images obtained in the observation campaign performed in a joint project between the Italian Space Agency (ASI) and the University of Bologna at the Broglio Space center, Kenya. © 2014 IAA. Published by Elsevier Ltd. All rights reserved.

Keywords: Automated image analysis | Object detection | Space debris | Star field

Abstract: This paper illustrates a Human-Machine Interface based on Augmented Reality (AR) conceived to provide to maintenance operators the results of an impact detection methodology. In particular, the implemented tool dynamically interacts with a head portable visualization device allowing the inspector to see the estimated impact position on the structure. The impact detection methodology combines the signals collected by a network of piezosensors bonded on the structure to be monitored. Then a signal processing algorithm is applied to compensate for dispersion the acquired guided waves. The compensated waveforms yield to a robust estimation of guided waves difference in distance of propagation (DDOP), used to feed hyperbolic algorithms for impact location determination. The output of the impact methodology is passed to an AR visualization technology that is meant to support the inspector during the on-field inspection/diagnosis as well as the maintenance operations. The inspector, in fact, can see interactively in real time the impact data directly on the surface of the structure. Here the proposed approach is tested on the engine cowling of a Cessna 150 general aviation airplane. Preliminary results confirm the feasibility of the method and its exploitability in maintenance practice. © 2014 SPIE.

Keywords: Aircraft Maintenance | Augmented Reality | Guided waves | Impact localization | Nondestructive Testing | Warped Frequency Transform

Abstract: A system for orbital object monitoring is analyzed, based on a mid-latitude and an equatorial observatory. The enhancements with respect to the use of a single telescope located at mid-latitude, for space debris detection and tracking are highlighted in terms of surveying volume, object identification, and orbital determination accuracy. The need to improve observation capabilities in monitoring and cataloguing such kinds of objects is constantly growing, due to the constant increase of operative satellites and space debris in both geostationary Earth orbit (GEO) and low Earth orbit (LEO) regions. After the considerations on the feasibility of the whole system, an overview of the observatories' design is sketched, on the basis of previous Italian experience in space debris observation, and taking into account constraints imposed by the instrumentation. In particular the main characteristics of components, software for image analysis and observation methodologies are analyzed and a possible configuration is given, based on the ALMASCOPE observatory realized by the Space Robotics Group at the University of Bologna. This observatory was used for the 2010 test campaign carried out from the Broglio Space Center in Kenya. © 2014 IEEE.

Abstract: This paper proposes an augmented reality (AR) strategy in which a Lamb waves based impact detection methodology dynamically interacts with a head portable visualization device allowing the inspector to see the estimated impact position (with its uncertainty) and impact energy directly on the plate-like structure. The impact detection methodology uses a network of piezosensors bonded on the structure to be monitored and a signal processing algorithm (the Warped Frequency Transform) able to compensate for dispersion the acquired waveforms. The compensated waveforms yield to a robust estimation of Lamb waves difference in distance of propagation (DDOP), used to feed hyperbolic algorithms for impact location determination, and allow an estimation of the uncertainty of the impact positioning as well as of the impact energy. The outputs of the impact methodology are passed to a visualization technology that yielding their representation in Augmented Reality (AR) is meant to support the inspector during the on-field inspection/diagnosis as well as the maintenance operations. The inspector, in fact, can see interactively in real time the impact data directly on the surface of the structure. To validate the proposed approach, tests on an aluminum plate are presented. Results confirm the feasibility of the method and its exploitability in maintenance practice. © 2013 Luca De Marchi et al.

Abstract: This paper describes the Multi Disciplinary Optimization of an airship with unconventional configuration. The shape of the airship is based upon two semi-ellipsoids, whose axis ratios can be altered for optimization purpose. The parameters to optimize are: volume, ratio between longitudinal and lateral semi-axis, ratio between vertical and lateral semi-axis, percentage of the top surface covered by photovoltaic films, dimension of the tail. The goals of the optimization are: equilibrium between buoyancy and weight, reaching of the design speed, static longitudinal stability of the vehicle. The mathematical model developed to evaluate airship features includes the computation of the ballonet volume, a weight breakdown, the energy storage for night operations, the power system evaluation and stability considerations. Six heuristic optimization strategies have been applied in order to achieve the best solution; some case studies have been developed and the final optimal configurations found by algorithms have been analyzed in order to validate the optimization framework. The approach demonstrate that the heuristic optimization strategies used are good tool for the conceptual design of unconventional airship since this problem requires a multi-disciplinary approach and several parameters including aerodynamics, propulsion, mass breakdown, aerostatics and stability, which are strongly dependent each other, must be jointly considered and addressed at the same time to obtain an optimum and balanced design. © 2013 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.

Abstract: This study deals with a mixed static and dynamic optimization of four-parameter functionally graded material (FGM) doubly curved shells and panels. The two constituent functionally graded shell consists of ceramic and metal, and the volume fraction profile of each lamina varies through the thickness of the shell according to a generalized power-law distribution. The Generalized Differential Quadrature (GDQ) method is applied to determine the static and dynamic responses for various FGM shell and panel structures. The mechanical model is based on the so-called First-order Shear Deformation Theory (FSDT). Three different optimization schemes and methodologies are implemented. The Particle Swarm Optimization, Monte Carlo and Genetic Algorithm approaches have been applied to define the optimum volume fraction profile for optimizing the first natural frequency and the maximum static deflection of the considered shell structure. The optimization aim is in fact to reach the frequency and the static deflection targets defined by the designer of the structure: the complete four-dimensional search space is considered for the optimization process. The optimized material profile obtained with the three methodologies is presented as a result of the optimization problem solved for each shell or panel structure. © 2013 Francesco Tornabene and Alessandro Ceruti.

Abstract: This paper describes an original application of heuristic optimization techniques to a complex multidisciplinary task. An unmanned aerial vehicle with a shape obtained by hot wire cutting techniques is designed for a typical civil mission, defining its geometry and aerodynamics with a particle swarm algorithm, a genetic algorithm and a Monte Carlo simulation. The tailless configuration of the vehicle requires an accurate design to satisfy all the requirements and obtain a low cost solution; only heuristic or semi-heuristic techniques can be applied because of the high non linearity of the problem and the large number of parameters to be defined. The three optimization methodologies have been applied to the problem, comparing their effectiveness on the basis of the computational weight. This study shows how the Rapid Prototyping techniques can be applied to the manufacturing of small lots of UAVs: the required optimal design is gained applying heuristic optimization techniques. The conclusions which can be drawn from this work confirm the suitability of optimization methods to non linear problems: genetic algorithms and particle swarm optimization provide similar results in term of fitness maximization, while Monte Carlo algorithm presents a lower efficiency. The easy implementation of the particle swarm optimization algorithm, compared to the more complex genetic algorithm, suggests how to use the former in optimization problems related to product design. © 2012 Springer-Verlag.

Keywords: Genetic algorithms | Hot wire cutting | Monte Carlo optimization | Particle swarm optimization | Unmanned aerial vehicle

Abstract: This paper describes the design and development of a virtual environment conceived to support flight operations of an Unmanned Air Vehicle (UAV) used for wind mapping in the proximity of existing or planned wind farms. The virtual environment can be used in pre-flight briefings aiming to define a trajectory from a list of waypoints, to change and eventually re-plan the mission in case of intersection with no fly zones, to simulate the mission, and to preview images/videos taken from the UAV on-board cameras. During flight, the tool can be used to compute the wind speed along the trajectory by analyzing the data streaming from the UAV. The integration of Augmented Reality (AR) techniques in the flight environment provides assistance in remotely piloted landings, and allows visualizing flight and environmental information that are critical to the mission. For example, when spatial and temporal knowledge of the wind speed is required, AR can be used to overlap wind speed vectors to the external real environment. Eventually, wind vectors and UAV position and attitude can be visualized in a Virtual Reality systems based on Cave Automatic Virtual Environments (CAVE) or stereoscopic view. Tests shows that the proposed tool and methodology can effectively support wind speed detection missions since it can improve operational safety and contribute to the accomplishment of mission goals. Copyright © 2013 SAE International.

Abstract: Added masses computation is a crucial aspect to be considered when the density of a body moving in a fluid is comparable to the density of the fluid displaced: added mass can be defined as the inertia added to a system because an accelerating or decelerating body displaces some volume of neighboring fluid as it moves through it. The motion of vehicles like airships and ships can be addressed only by keeping into account the effect of added masses, while in case of aircrafts and helicopters this contribution is usually neglected. Lighter Than Air flight simulation, unmanned airships flight control system, airships flight dynamics are typical applications in which added masses are fundamental to achieve an effective and realistic modeling. A panel based method using the mesh of an airship external shape is developed to account for the added massed. While the mathematical background of the methodology is described in literature, what is missing is a proper description suitable for unconventional manned/unmanned airship. Two applications of the methods have been carried out to check the precision of the methods, and results have been also compared to a case study whose added masses are described in literature. A sensitivity study on the effect on the added masses of the number of elements in which the envelope is discretized is performed. Finally, for an unconventional unmanned airship model, the computations of the terms of the added masses matrix are shown. Copyright © 2013 SAE International.

Abstract: Scaled models are often used to check the aerodynamic performance of full scale aircraft and airship concepts, which have gone through a conceptual and preliminary design process. Results from these tests can be quite useful to improve the design of unconventional airships whose aerodynamics might be quite different from classical configurations. Once the airship geometry has been defined, testing is required to acquire aerodynamic data necessary to implement the mathematical model of the airship needed by the flight control system to develop full autonomous capabilities. Rapid prototyping has the great potential of playing a beneficial role in unconventional autonomous airship design similarly to the success obtained in the design process of conventional aircrafts. By reducing model cost, build time, difficulty of construction, and maintaining acceptable surface quality and finish, designers have greater ability to analyze several configurations of airships and to change the geometry in order to increase stability, reduce drag, or fulfill mission requirements. This work presents aspects of unmanned airship design which are supported by the use of RP techniques: a test model of a multi-body, cruiser-feeder unconventional airship system has been developed using hot wire cutting and SST printing technology which helped to construct necessary parts for complex body shapes. Taking into account actual model shape and material properties, model verification checks were performed on the final products through FEM and CFD analysis to ensure structural strength and integrity during test procedures and to virtually simulate wind tunnel tests; experimental data from the wind tunnel campaigns are then used in the development of an unmanned airship flight simulator, which is of critical importance in multi-body concepts when cruiser/feeder configurations need to perform docking and rendezvous maneuvers. Results which assess the quality of the test models by comparison of wind tunnel results to CFD simulations are also presented; a final discussion of advantages obtained applying RP technique to the airship design cycle concludes the paper. Copyright © 2013 SAE International.

Abstract: Unmanned Aerial Vehicles (UAVs) provide the ability to perform a variety of experimental tests of systems and unproven research technologies, including new autopilot systems and obstacle avoidance capabilities, without risking the lives of human pilots. This paper describes the activities of design, optimization, and flight operations of a UAV conceived at Clarkson University (USA) and equipped to perform wind speed measurements to support wind farmsite planning. The UAV design has been assisted and validated by the use of an automatic virtual environment for the assisted design of civil UAVs. This tool can be used as a "computing machine" for civil UAVs. The operator inputs the mission profile and other generic parameters and data about performance, aerodynamics, and weight breakdown are extracted. A mathematical model of the UAV for flight simulation and its dynamic computations, along with automatic drawing is also produced. Also an optimizer based on genetic algorithms has been added to the tools, so that the UAV design can be iteratively improved in order to most effectively perform the mission selected. A detailed design of the UAV was carried out using traditional methodologies, and results compared with new tools like X-PLANE simulator. The static stability computations described are deemed to be effective since the evaluation of the UAV pilot on flying qualities correlates with predictions. Copyright © 2013 SAE International.

Abstract: Stirling engines are close cycle motors which can output mechanical work following a difference in temperature of two whatever thermal sources. This paper presents the preliminary design and the optimization of a system composed by a Low Differential Temperature Stirling Engine moving a simple single effect reciprocating water pump. The heat source is solar radiation, so that the engine can be installed in developing countries or in remote installation, without the need for fossil fuels. According to literature, the design of a Stirling engine is a complex task, since a lot of parameters should be considered at the same time; a mathematical model of the whole system, based on the second order theory for Stirling engine, has been implemented. In the following, it has been exploited to perform the optimization of the engine/pump mechanical system: maximum water flow for given maximum engine dimensions is the design goal of this problem. The Genetic Algorithms, Particle Swarm, Monte Carlo, Differential Evolution, Imperialist Comptetitive, and Simulated Annealing heuristic algorithms have been applied to solve the problem and to compare each other. The results obtained confirm the usefulness of the optimization in supporting the designer in such a complex task, in which a very accurate design is necessary to increase the efficiency of the system.

Abstract: This paper describes the development of an innovative hardware and software tool useful to sketch planar shapes in computer aided industrial design and computer aided design systems. The proposed system is based upon a tracked touch screen hand-held by the designer. The whole system is composed by a portable hand-held small touch screen (tablet size), a fixed LCD display and an optical tracking equipment. The touch screen is added by a simple camera for mixed reality optional functionality and its 6° of freedom movements are tracked. A custom software has been implemented for optimal exploitation and 3D sketching. The system acts as a free sketching device, a 3D mouse, as a realtime virtual and physical sketching plane or an external shape remodelling tool. The results obtained confirm the benefits of the virtual tablet in design, modelling and reverse engineering of industrial products. Copyright © 2013 Inderscience Enterprises Ltd.

Keywords: Computer aided sketching | Pose estimation | Reverse engineering | Sensor fusion | Touch screen tablet

Abstract: Recent years have seen an outpour of revived interest in the use of airships for a number of applications.Present day developments in materials, propulsion, solar panels, and energy storage systems and the need for a more eco-oriented approach to flight are increasing the curiosity in airships, as the series of new projects deployed in recent years show; moreover, the exploitation of the always mounting simulation capabilities in CAD/CAE, CFD and FEA provided by modern computers allow an accurate design useful to optimize and reduce the development time of these vehicles.The purpose of this contribution is to examine the different aspects of airship development with a review of current modeling techniques for airship dynamics and aerodynamics along withconceptual design and optimization techniques, structural design and manufacturingtechnologies and, energy system technologies. A brief history of airships is presented followed by an analysis of conventional and unconventional airships including current projects and conceptual designs. © The Korean Society for Aeronautical & Space Sciences.

Keywords: Aerodynamics | Airships | Design | Dynamics | Energy Systems | Structures

Abstract: This paper describes the development of an innovative harware and software tool useful to sketch planar shapes in Computer-aided Industrial Design and Computer Aided Design systems. The whole system is composed by a portable hand-held small touch-screen, a large fixed main screen and an optical tracking equipment. The touch-screen is added by a simple camera for Mixed Reality optional functionality and its 6 degrees of freedom movements are tracked through four groups of Light Emitting Diodes located on back of the monitor. A Nintendo® WiiMote with infrared camera is used to acquire Light Emitting Diodes relative positions for real-time tracking. A 6 degrees of freedom Inertial Measurement Unit has been added to improve the stability of the pose estimation: an Extended Kalman Filter provides the data fusion. Furthermore, a custom software has been implemented for optimal exploitation of a such configured hardware and facilitate input and 3D sketching. The physical tablet can be used in three different ways: as a 3D mouse which sets the point of view of the main screen according to its attitude, to set a plane in the main screen so that a 2D sketch can be referenced in the 3D space and as a support device to improve the manual draw of an object by overwriting the image contour. The results obtained confirms the usefulness of the virtual tablet in design, modelling, and reverse engineering of industrial products. © Organizing Committee of TMCE 2010 Symposium.

Keywords: Computer aided sketching | Pose estimation | Reverse engineering | Sensor fusion | Virtual tablet

Abstract: This paper reports the results of a PDM and CAD plug-in implementation for semi-automatic and real-time similar component search in mechanical field. The approach exploits a string based component description similar to the well-known methodology, called Group Technology (GT), in order to check interactively feature similarity over a PDM database. The GT code contains component geometric data and manufacturing information. The software developed is suitable for encoding 2D and 3D parts. A guided GUI returning the GT code has been implemented for 2D drafts. For 3D parts, instead, the encoding procedure is completely integrated in the modelling CAD interface and the code is calculated incrementally feature by feature. So the part similarity assessment is interactive: the designer may visualize similar parts stored in the PDM and decide whether changing singular feature or using a retrieved (similar) part. Several case studies described in the paper demonstrate GUI usage, search algorithm and results. With PDM correctly configured, results are very good since the GT coding, the part retrieval and the quoting are really interactive. © 2010 CAD Solutions, LLC.

Keywords: Cost prediction | GT code | Interactivity | Similarity assessment

Abstract: This paper describes the design and manufacturing of the Agusta Westland flight mechanics simulator for rotorcraft design. The aims of the simulator are the design of the handling qualities of any new rotorcraft, the simulation of flight manoeuvres, including those following engine failures and tail rotor loss, the instruments panel lay-out optimisation, etc.. The simulator has no motion capability and it is equipped with a pilot seat plus one assistant seat with no command lines. The pilot's flight controls have four Moog motors for control loading of the feedback force. The simulator is driven by a home code named SIMENV that interfaces all the off the shelf software packages running in the simulation of rotorcraft flight (MATLAB®, VEGA®, VAPS®, Flightlab®). The out of the window display is provided by three video projectors on an emicylindrical screen with 6m of diameter. Two more LCD monitors, placed near the pilot's feet, give the ground view, so that the feeling of being onboard is increased and take-off and landing manoeuvres can be simulated. A cluster of 13 PCs give the computational power for real time simulation and visual generation. The simulator described in the paper is now operational and currently used to improve the factory design chain efficiency. This paper presents also some diagrams explaining the activity of simulation performed to validate this design tool. Results obtained are good and the simulator ongoing work plays an important role in the conceptual phase of AgustaWestland helicopter design process. By this, not only engineers but also the pilot can now be involved in the helicopter design from the initial phase of the activity process.

Keywords: Flight dynamics and control | Flight testing and simulation | Simulator design