Abstract: This paper formulates quadrilateral elements for the NURBS-enhanced finite element method (NEFEM). The objective is to extend the application of NEFEM to problems where the use of quadrilateral elements is preferred. By leveraging a mapping, between reference and physical spaces, that encapsulates the exact boundary representation of the domain, a tight integration with computer aided design (CAD) systems is achieved. The contribution of this work is an enhanced quadrilateral finite element that incorporates the exact CAD geometry purely from the boundary representation (B-rep) from CAD and without the need for a whole volume representation (V-rep) as a NURBS entity. Numerical examples involving heat transfer and linear elastic problems are used to numerically demonstrate the optimal convergence properties of the method under mesh refinement.

Keywords: CAD integration | NEFEM | Quadrilateral elements

Abstract: The paper focuses on the application of 3D printing technology in the medical field, particularly in cardiac surgery. Unlike traditional imaging techniques such as CT, MRI, and ultrasound, 3D printing offers a more detailed understanding and analysis of clinical cases. By using 3D printing, it becomes possible to study a patient’s specific cardiac anatomy, manipulate objects before surgery, and accurately determine the surgical site. This reduces both the time required for the operation and the patient’s recovery period. This study presents a methodology for creating 3D-printed models of aortic arch sections affected by aortic dissection. The aim is to produce anatomical models with varying levels of quality and accuracy. The research goal is to assess the differences in 3D printing materials and technologies for creating complex anatomical models like the aorta. The process involves segmenting medical images obtained from Computed Tomographic Angiography (CTA) and then 3D printing digital models using different materials (such as PLA, TPU, and resin) and technologies (like FDM and SLA). The resulting 3D printed models are low-cost and demonstrate good accuracy in reproducing human anatomy.

Keywords: 3D Printing | CAD | Cardiac surgery | Engineering method

Abstract: In this article, our aim is to underscore the importance of verifying that components produced through material extrusion additive manufacturing exhibit geometric and dimensional conformity with the STL (Standard Tessellation Language) model. Currently, the business world is heavily investing in additive technologies, but it is crucial to obtain feedback on the accuracy of the printed component without excessive economic expenditure. For this reason, we have opted to utilize a mid-range 3D scanner (Revopoint Mini with an accuracy of 0.02 mm) to investigate any disparities in print results using PLA material. Each model has been scanned and compared with the initial mesh to qualitatively and quantitatively assess the present errors. The analysis has revealed that the majority of features can be effectively controlled, while the remaining ones either fall within the tool's precision or necessitate a higher-quality scan. Particularly in the analysed case, flat surfaces, profiles of complex geometries, and holes have demonstrated dimensional and geometric controllability. However, details of reduced dimensions or those difficult to reach by the scanner do not allow for adequate comparison due to excessive standard deviation in the error. The analysed layer heights do not exhibit a significant impact on component accuracy.

Keywords: 3D scanning | Cost-effective | Dimensional accuracy | Material extrusion | Quality control

Abstract: Functionally graded materials (FGMs) using the finite element method (FEM) with C0 elements, focusing on the examination of material variable parameters. The research advances the understanding of FGMs through a thermo-structural analysis of an FGM disk, assessing its response under thermal and mechanical loads. Thermal and thermo-mechanica analysis demonstrates the precision of the proposed approach in delineating the complex behavior of FGMs under diverse conditions. The research contributes to enrich the comprehension of FGM behavior using simple FEM models.

Keywords: Analytical Solution | Composites | FEM | FGM | Materials | Numerical Solution

Abstract: ‘Repair’ in the design process of products can prolong the life cycle of parts: this is substantiated by a few examples that put this ideology into practice. Among many other products, home printers could be a good example, with huge numbers of printers ending up in landfill after a relatively short life; often due to blocked print heads that are either impossible or too expensive to replace. The act of fixing things can both prolong the life of an artifact, and create new values through the process of engagement for its users. However, the prohibitive cost of repair makes it inaccessible or unfavorable this practice for many. In this paper a preliminary approach to Design for Repair is proposed, in order to virtually test an industrial case study and to show a comparison between a product, that was intended to disposal after a failure of some components, and the same product re-designed, by taking into account how to repair parts in easy and effective way. Redesign of parts in some cases can be very effective and the virtual test can be easily reproposed in practice, for industrial products. Advantages in the repair of parts is evident in terms of sustainability and circular economy pursuit. This paper suggests a sequenced method to approach the Design for Repair and provide the virtual model of a re-designed solution that could replace the previous one in order to make the repair of components easy and effective. The economic analysis on the effective convenience of repair faced to the disposal of a product was not developed within this context.

Keywords: Circular economy | Design for Disassembly | Design for Repair | Gearmotor | Sustainability

Abstract: This paper analyzed a simple joint with the Goland-Reissner (G-R) theory. The study's primary purpose is to define specific boundary conditions that depend on several factors to minimize the use of complex finite element analysis in the well-known applications. The problem depends on the length of the adhesions area and the magnitude of axial load P. The joint was first considered rigid to evaluate the stresses at its extremes, after which the theory of G-R was applied, considering the cases of equal and different adhesions. A mathematical approach was carried out starting from the equilibrium of the infinitesimal element. The results were finally compared with the Finite Element Method using FEM code.

Keywords: FEM | glue connection | Goland-Reissner

Abstract: The lifecycle of a product is getting shorter in today’s market realities. Latest developments in the industry are heading towards achieving products that are easy to recycle, by developing further technological advances in raw materials ought to include input from End of Life (EOL) products so a reduction of natural harm could be achieved, hence reducing the overall production environmental footprint. Therefore, the approach taken as a design for environment, a key request nowadays in order to develop products that would ease the reverse manufacturing process leading to a more efficient element recycling for later use as spare parts or remanufacturing. The methodology proposed compares three probable disassembly sequences following a comparison of literature-found procedures between genetic algorithms and as a “state space search” problem, followed by a hybrid approach developed by the authors. Time and evaluation of these procedures reached to the best performing sequence. A subsequent augmented reality disassembly simulation was performed with the top-scored operation sequence with which the user is better able to familiarize himself with the assembly than a traditional paper manual, therefore enlightening the feasibility of the top performing sequence in the real world.

Keywords: closed loop | Disassembly | genetic algorithms | metaheuristic method | optimization | particle swarm optimizer

Abstract: Many industrial technologies are developed to optimize products and bring innovation. In particular, the automotive sector is renewing itself according to the rules of green energy and consumption. This huge change requires a reinterpretation of the models on the market updating them to the present and the future needs of automotive industry. In this paper the best compromise between innovation and tradition is found for the Ford brand that has not yet presented electric cars in the sedan segment. Following the SDE method enriched with Quality Function Deployment (QFD), Benchmarking (BM) and Top Flop Analysis (TPA), it is possible to carry out an innovative project. All these technologies must, however, be ordered according to a specific product allowing the best result for the design process. It is therefore necessary identifying the most common stylistic trends in order to draw the external styling of the vehicle using virtual prototyping techniques. To achieve an innovative result, Augmented Reality (AR) is considered to complete the method substituting the static and expensive procedure of making maquettes.

Keywords: Additive manufacturing | Augmented reality | Benchmarking | Car design | Design engineering | QFD | Stylistic design engineering (SDE)

Abstract: Torsional deformities of the lower limb are common in children with cerebral palsy (CP)-determining gait problems. The mechanisms underlying transverse plane gait deviations arise from a combination of dynamic and static factors. The dynamic elements may be due to spasticity, contractures and muscle imbalances, while the static ones may result from excessive femoral anteversion, which decreases the efficiency of the hip abductors by reducing the muscular lever arms. A therapeutic approach has been identified in multi-level functional surgery for the lower limb. Treating the malalignments of the lower limb with femoral or tibial derotation provides optimal results, especially when supported by adequate biomechanical planning. This planning requires an integrated static-dynamic approach of morphological and functional evaluation, based on radiological measurements, physical examination and gait analysis. Instrumented gait analysis has been confirmed as essential in the evaluation and surgical decision making process for children affected by CP with transverse plane deformities. Computational simulations based on musculoskeletal models that integrate patient-specific CT morphological data into gait analysis can be used for the implementation of a surgical simulation system in pre-operative planning to test the possible effects of the different surgical treatment options on the torsional defects of the lower limbs. Recently, a computer-aided simulation process has been implemented in the preoperative planning of complex osteotomies for limb deformities in children. Three-dimensional (3D) digital models were generated from Computed Tomography (CT) scans, using free open-source software. The aim of this study is to integrate the patient-specific CT musculoskeletal model with morphological data and gait analysis data, with the personalized calculation of kinematic and kinetic parameters, which allow us to generate an “avatar” of the patient for a more in-depth evaluation of the gait abnormalities. The computational simulation platform proposed provides a realistic movable musculoskeletal model in a virtual environment, with the possibility of planning and monitoring the effects of virtual three-dimensional surgical corrections.

Keywords: avatar | cerebral palsy | computed tomography | derotation | gait analysis | musculoskeletal modeling | torsional deformities | virtual surgical planning

Abstract: Fused Deposition Modelling (FDM) technology allows to choose a large variety of materials and it is widely used by companies and individuals nowadays. The cost effectiveness of rapid prototyping is achievable via FDM, that makes this technology useful for research and innovation. The application of 3D printing to aid production is the most common approach. Moreover, the use of 3D printing in prototypes result in a waste of material since no reuse is considered. In the following manuscript, this technology is applied to mould fabrication by achieving a low surface roughness at a modest cost compared to conventional manufacturing methods. Moreover, the possibility to use a combination of thermoplastic materials is analysed by examination of the CAD model optimized for Additive Manufacturing (AM) from scratch and was verified using metrology tools. Several moulds were finally built and applied to the specific case study of carbon fibre laminated components. This manuscript aims to analyse the manufacturing process by comparing the mould surface geometry before and after the smoothing process. The achieved tolerance between the produced moulds is ±0.05 mm that ensures the repeatability of the process from an industrial point of view; whilst the deviation between CAD and mould is ±0.2 mm. To combine an accurate FDM process together with chemical smoothing proved to be a powerful strategy to produce high quality components that can be inserted in the production process by means of traditional manufacturing techniques. This will aid to reduce the cost of standard manufacturing for low production batches and prototypes of carbon fibre composites.

Keywords: Carbon fibre mould | Chemical smoothing | FDM | Multimaterial FDM | PLA | PVB | Vapor smoothing

Abstract: Complex deformities of lower limbs are frequent in children with genetic or metabolic skeletal disorders. Early correction is frequently required, but it is technically difficult and burdened by complications and recurrence. Herein, we described the case of a 7-year-old girl affected by severe bilateral genu varum due to spondyloepiphyseal dysplasia. The patient was treated by patient-specific osteotomies and customized structural wedge allograft using Virtual Surgical Planning (VSP) and 3D-printed patient-specific instrumentation (PSI). The entire process was performed through an in-hospital 3D-printing Point-of-Care (POC). VSP and 3D-printing applied to pediatric orthopedic surgery may allow personalization of corrective osteotomies and customization of structural allografts by using low-cost in-hospital POC. However, optimal and definitive alignment is rarely achieved in such severe deformities in growing skeleton through a single operation.

Keywords: 3D-printing | cutting guide | in-hospital | osteotomy | patient-specific instruments | pediatric | point-of-care | spondyloepiphyseal dysplasia | structural allograft | VSP

Abstract: Improvements in software for image analysis have enabled advances in both medical and engineering industries, including the use of medical analysis tools to recreate internal parts of the human body accurately. A research analysis found that FDM-sourced elements have shown viability for a customized and reliable approach in the orthopedics field. Three-dimensional printing has allowed enhanced accuracy of preoperative planning, leading to reduced surgery times, fewer unnecessary tissue perforations, and fewer healing complications. Furthermore, using custom tools chosen for each procedure has shown the best results. Bone correction-related surgeries require customized cutting guides for a greater outcome. This study aims to assess the biopolymer-based tools for surgical operations and their ability to sustain a regular heat-sterilization cycle without compromising the geometry and fit characteristics for a proper procedure. To achieve this, a DICOM and FDM methodology is proposed for fast prototyping of the cutting guide by means of 3D engineering. A sterilization test was performed on HTPLA, PLA, and nylon polymers. As a result, the unique characteristics within the regular autoclave sterilization process allowed regular supplied PLA to show there were no significant deformations, whilst annealed HTPLA proved this material’s capability of sustaining repeated heat cycles due to its crystallization properties. Both of these proved that the sterilization procedures do not compromise the reliability of the part, nor the safety of the procedure. Therefore, prototypes made with a similar process as this proposal could be safely used in actual surgery practices, while nylon performed poorly because of its hygroscopic properties.

Keywords: 3D engineering | Cutting guide | FDM | HTPLA | Nylon FDM | Preoperative planning | Sterilization

Abstract: Fused Deposition Modeling (FDM) 3D printing is the most widespread technology in additive manufacturing worldwide that thanks to its low costs, finished component applications, and the production process of other parts. The need for lighter and higher-performance components has led to an increased usage of polymeric matrix composites in many fields ranging from automotive to aerospace. The molds used to manufacture these components are made with different technologies, depending on the number of pieces to be made. Usually, they are fiberglass molds with a thin layer of gelcoat to lower the surface roughness and obtain a smooth final surface of the component. Alternatively, they are made from metal, thus making a single carbon fiber prototype very expensive due to the mold build. Making the mold using FDM technology can be a smart solution to reduce costs, but due to the layer deposition process, the roughness is quite high. The surface can be improved by reducing the layer height, but it is still not possible to reach the same degree of surface finish of metallic or gelcoat molds without the use of fillers. Thermoplastic polymers, also used in the FDM process, are generally soluble in specific solvents. This aspect can be exploited to perform chemical smoothing of the external surface of a component. The combination of FDM and chemical smoothing can be a solution to produce low-cost molds with a very good surface finish.

Keywords: Carbon fiber mold | Chemical smoothing | FDM | PVB | Vapor smoothing

Abstract: Additive manufacturing processes have evolved considerably in the past years, growing into a wide range of products through the use of different materials depending on its application sectors. Nevertheless, the fused deposition modelling (FDM) technique has proven to be an eco-nomically feasible process turning additive manufacture technologies from consumer production into a mainstream manufacturing technique. Current advances in the finite element method (FEM) and the computer-aided engineering (CAE) technology are unable to study three-dimensional (3D) printed models, since the final result is highly dependent on processing and environment parame-ters. Because of that, an in-depth understanding of the printed geometrical mesostructure is needed to extend FEM applications. This study aims to generate a homogeneous structural element that accurately represents the behavior of FDM-processed materials, by means of a representative volume element (RVE). The homogenization summarizes the main mechanical characteristics of the actual 3D printed structure, opening new analysis and optimization procedures. Moreover, the linear RVE results can be used to further analyze the in-deep behavior of the FDM unit cell. Therefore, industries could perform a feasible engineering analysis of the final printed elements, allowing the FDM technology to become a mainstream, low-cost manufacturing process in the near future.

Keywords: Additive manufacturing | FDM | FEM | Linear analysis | Microstructure behavior | RVE

Abstract: The design of an E segment, executive, midsize sedan car was chosen to fill a gap in the market of the Ford brand and to achieve the goal of innovation looking towards the future. Ford has not owned an E-segment flagship sports sedan for years, since the historic 1960s Falcon. Starting from the latter assumption and considering that the major car manufacturers are currently investing heavily in E-segment cars, it is important to design a new model, which has been called the Eagle. This model proposed here is to fill the gap between Ford and other companies that are already producing sport cars for the electric sector and to complete Ford’s proposal. The presented methodology is based on SDE, on which many design tools are implemented, such as Quality Function Deployment (QFD), Benchmarking (BM), and Top Flop Analysis (TPA). A market analysis follows in order to identify the major competitors and their key characteristics considering style and technology. The results are used to design an innovative car. Based on the most developed stylistic trends, the vehicle is first sketched and then drawn in the 2D and 3D environments for prototyping. This result leads to the possibility of 3D printing the actual model as a maquette using the Fused Deposition Modelling (FDM) technology and testing it in different configurations in Augmented Reality (AR). These two final applications unveil the possibilities of Industry 4.0 as enrichment for SDE and in general rapid prototyping.

Keywords: Additive manufacturing | Augmented reality | Benchmarking | Car design | Design engineering | QFD | Stylistic design engineering (SDE)

Abstract: Technology evolution and wide research attention on 3D printing efficiency and processes have given the prompt need to reach an understanding about each technique’s prowess to deliver superior quality levels whilst showing an economical and process viability to become mainstream. Studies in the field have struggled to predict the singularities that arise during most Fused Deposition Modeling (FDM) practices; therefore, diverse individual description of the parameters have been performed, but a relationship study between them has not yet assessed. The proposed study lays the main defects caused by a selection of printing parameters which might vary layer slicing, then influencing the defect rate. Subsequently, the chosen technique for optimization is presented, with evidence of its application viability that suggests that a quality advance would be gathered with such. The results would help in making the FDM process become a reliable process that could also be used for industry manufacturing besides prototyping purposes.

Keywords: Defects | Optimization | Optimized FDM | Printing parameters | Void occurrence

Abstract: Three-dimensional printed custom cutting guides (CCGs) are becoming more and more investigated in medical literature, as a patient-specific approach is often desired and very much needed in today’s surgical practice. Three-dimensional printing applications and computer-aided surgical simulations (CASS) allow for meticulous preoperatory planning and substantial reductions of operating time and risk of human error. However, several limitations seem to slow the large-scale adoption of 3D printed CCGs. CAD designing and 3D printing skills are inevitably needed to develop workflow and address the study; therefore, hospitals are pushed to include third-party collaboration, from highly specialized medical centers to industrial engineering companies, thus increasing the time and cost of labor. The aim of this study was to move towards the feasibility of an in-house, low-cost CCG 3D printing methodology for pediatric orthopedic (PO) surgery. The prototype of a femoral cutting guide was developed for its application at the IOR—Rizzoli Orthopedic Institute of Bologna. The element was printed with an entry-level 3D printer with a high-temperature PLA fiber, whose thermomechanical properties can withstand common steam heat sterilization without bending or losing the original geometry. This methodology allowed for extensive preoperatory planning that would likewise reduce the overall surgery time, whilst reducing the risks related to the intervention.

Keywords: 3D printing | CAD surgery simulation | CASS | CT scan | Cutting guide | Orthopedic reproduction model

Abstract: This experimental study defines the usage of a computer-aided surgical simulation process that is effective, safe, user-friendly, and low-cost, that achieves a detailed and realistic representation of the anatomical region of interest. The chosen tools for this purpose are state-of-the-art Computer Aided Design (CAD) software for mechanical design, and are the fundamental application dedicated to parametric modeling. These tools support different work environments, each one is for a specific type of modeling, and they allow the simulation of surgery. The result will be a faithful representation of the anatomical part both before and after the surgical procedure, screening all the intermediate phases. The doctor will assess different lines of action according to the results, then he will communicate them to the engineer who, consequently, will correct the antisymmetric issue and regenerate the model. Exact measurements of the mutual positions of the various components, skeletal and synthetic, can be achieved; all the osteosynthesis tools, necessary for the surgeon, can be included in the project according to different types of fracture to perfectly match the morphology of the bone to be treated. The method has been tested on seven clinical cases of different complexity and nature and the results of the simulations have been found to be of great effectiveness in the phase of diagnosis and of preoperative planning for the doctors and surgeons; therefore, allowing a lower risk medical operation with a better outcome. This work delivers experimental results in line with theoretical research findings in detail; moreover, full experimental and/or methodical details are provided, so that outcomes could be obtained.

Keywords: 3D processing | CAD-aided | Customized surgery | Pediatric orthopedics | Preoperative planning | Surgical simulation

Abstract: The study of CAD (computer aided design) modeling, design and manufacturing techniques has undergone a rapid growth over the past decades. In medicine, this development mainly concerned the dental and maxillofacial sectors. Significant progress has also been made in orthopedics with pre-operative CAD simulations, printing of bone models and production of patient-specific instruments. However, the traditional procedure that formulates the surgical plan based exclusively on two-dimensional images and interventions performed without the aid of specific instruments for the patient and is currently the most used surgical technique. The production of custom-made tools for the patient, in fact, is often expensive and its use is limited to a few hospitals. The purpose of this study is to show an innovative and cost-effective procedure aimed at prototyping a custom-made surgical guide for address the cubitus varus deformity on a pediatric patient. The cutting guides were obtained through an additive manufacturing process that starts from the 3D digital model of the patient’s bone and allows to design specific models using Creo Parametric. The result is a tool that adheres perfectly to the patient’s bone and guides the surgeon during the osteotomy procedure. The low cost of the methodology described makes it worth noticing by any health institution.

Keywords: 3D Printing | CAD Modeling | Cutting guides | Pediatric orthope-dics | Preoperative simulation | Surgery and diagnostics

Abstract: Annulus pipe conveying fluids have many practical applications, such as hydraulic control lines and aircraft fuel lines. In some applications, these tubes are exposed to high speeds. Normally, this leads to a vibration effect which may be of a catastrophic nature. The phenomenon is not only driven by the centrifugal forces, but an important role is played also by the Coriolis forces. Many theoretical approaches exist for a simple configuration or a complex three-dimensional configuration. Finite element models are tested. This paper provides a numerical technique for solving the dynamics of annulus pipe conveying fluid by means of the mono-dimensional Finite Element Method (FEM). In particular, this paper presents a numerical solution to the equations governing a fluid conveying pipeline segment, where a Coriolis force effect is taken into consideration both for fix and hinge constraint.

Keywords: Coriolis | FEM | Pipe conveying fluid | Simulation

Abstract: Software for image analysis endorsed further developments in the medical area that would accept state of the art reengineering processes to reproduce actual internal organs and structures of the human body. Previous research on FDM produced elements in the medicine field shown important discoveries on orthopedics. Preoperative planning shown to be suitable for additive manufacturing solutions that could help to improve the efficiency on procedures lowering potential risks after surgery. Accurate and well thought planning is necessary to choose the best way for the practice and deliver the best results. Tooling customization has shown to help into achieving this result. Bone-related surgeries require customized cutting guides for better accuracy. The following work aims to deliver the opportunity to use variations of Polylactic acid (PLA) based cutting guides in actual surgery practices by means of sustaining a regular heat-sterilization procedure without compromising its tailor-made characteristics. This would be possible by means of a proved, reliable procedure for obtaining the prototype from traditional CT scan images. As a result, HTPLA material composition and crystallization properties allowed to sustain a sterilization procedure in a way that does not compromise the reliability of the part, nor the safety of the procedure, so prototypes made with a similar process as the proposed one, can be used in actual surgery practices with safety.

Keywords: 3D Engineering | Cutting Guide | FDM | HTPLA | Sterilization

Abstract: Nowadays there is a trend of development of a number of FDM-sourced elements that have improved the ways for fast prototyping. CAE software technologies enabled sharing of knowledge across different sectors in the industry, there are important research findings in the medical area in which FDM implies an interesting and a rather efficient option for surgical procedure assessment; mainstream PLA has been a matter of various studies trying to understand its behavior to its limits, a heat treatment on PLA materials could allow to have different, and more diverse applications. HTPLA is another variation that deserves attention due to its prospective. This material has proven to expand the availability of PLA to different sectors because of its rather ease printability and higher heat-resistance. This study would assess the properties of neat PLA and HTPLA printed with optimized parameters, in addition of an annealing process that would modify its internal structure. Results suggest that HTPLA can resist higher temperatures and stress changes whilst scoring lower elongation and tensile response degrading.

Keywords: Annealing | FDM | HT-PLA | Polymers | Tensile Testing

Abstract: This work shows a preoperative simulation procedure with Computer Aided Design (CAD) 3D software for a patient suffering from Ollier's disease. This pathology is very rare and occurs in extremely different ways depending on the case. Consequently, it is difficult to establish a correct surgical strategy that can be applied in a similar way to all patients. Computer Aided Surgical Simulation (CASS) process uses advanced modeling technologies to reproduce bony anatomy and simulate the surgery. The starting point is represented by the 3D digital model of the bone obtained from tomographic images. Through CAD modeling software such as Creo Parametric and following surgeons directives, engineers can provide doctors with orthopedic simulation and expectation of achievable surgical outcome. If virtual surgical prediction doesn’t meet doctors requirements, model is regenerated and it is possible to seek for a better solution. CASS process allow for extensive surgical planning, enhancing accuracy in theatre and enriching the amount of medical information that is needed to perform complex orthopedic procedures. In conclusion, the possibility to recognize in advance the overall orthopedic situation and outcoming expectancy represent an extraordinary upgrade of current surgical state of the art, leading to minimally invasive surgeries and patient-specific solutions.

Keywords: 3D modeling | CAD | CASS | Parametric software | Preoperative planning

Abstract: Additive manufacturing technologies have evolved rapidly and steadily over the last decade and they become widely used not only in large, high-level companies, but also in medium-sized industries for both the production of prototypes, mockups, and the production of finished components. Stratasys' patented fused deposition modelling (FDM) technology, or more generally Fused Filament Fabrication (FFF), is by far the most cost-effective additive manufacturing (AM) technology especially if compared to powder technologies such as selective laser melting. It offers an extremely wide range of materials from nowadays mainstream, low-cost polylactic acid to the more advanced carbon fiber PEEK. The use of this technology is usually finalized on the production of prototypes and few case studies of end-use components can be found in the literature. This is due to the difficulties in predicting the final behavior of the resulting component and the presence of defects that can cause unpredictable premature failures in the component. This study focuses on describing how it is possible to reduce the defects present in the component with a careful choice of printing parameters and in particular focus on the effect of the parameter called “line width” and its correlation with the geometry of the printable part. The results would help to make FFF a more reliable process that could be used for obtaining a reliable, industrial production as well as prototype manufacture.

Keywords: FDM defects | Line width | Optimized FFF | Printing parameters

Abstract: This manuscript presents a simplified approach to adhesive joints calculation. Aviation and space rocket engineering constructions joints deals with coaxial cylindrical pipes that can be connected by adhesive with advantages in terms of tightness, aerodynamic efficiency, manufacturability, low weight. Glue joints are, therefore, considered and simplified in this article by the analytical calculation of the shape functions for a macro-element applied to the Volkersen’s theory. The mathematical solution makes possible to calculate the explicit form of the stiffness matrix of the macro-element. The analysis proposed shows the perfect matching of the solution for a single element under classical mechanical loads.

Keywords: FEM | glue connection | macro-element | shape function

Abstract: This paper presents a study based on Design for Disassembly (DfD) applied to a hydraulic pump through the Disassembly Geometry Contacting Graph (DGCG) methodology. DfD is today very important to reduce the disposal or maintenance costs foreseeable already in the planning phase. One of the key points in reducing costs is reducing time for disassemble each component. Because of that, the disassembly time was considered respect to other fundamental and optimizable characteristics such as: Disassembly costs, operations to be performed, quantity of material, etc. All the operations have been evaluated using the time measurement units (TMUs). The objective of the paper is to minimize the disassembly times required for an operator to separate each single component from the other. The study of accessibility, positioning, strength, and basic time led to a comparison between different disassembly methods in order to produce the optimal sequence. In the end, the validation of the sequence was carried out in an Augmented Reality (AR) environment in order to predict the manual disassembly understanding the possible issues without the need of building the components. Using AR, it was possible to look at the assembly during the design phase in a 1:1 scale and evaluate the chosen sequence.

Keywords: CAD | Disassembly | Sequence | TMU | Virtual Reality

Abstract: In the last decade citizens mobility is changing towards a more environment-friendly, more flexible and more shared way of moving around the city. The objective, now, is to decrease the levels of pollution. Notwithstanding people mobility is based on rapidity, sustainability is becoming always more important. In order to follow the new needs of future customers, the present work is presenting a new approach to design in order to obtain an innovative product with the aforementioned characteristics. The new approach is to combine two innovative methodology to design: The first one is Design For Six Sigma (DFSS) and it is useful to structure the project into five main phases (Define, Measure, Analyze, Design, Validate), systematically; the second one is Stylistic Design Engineering (SDE) and it is dedicated to the aesthetic development of a new product following an engineering structure of all the phases of the work. DFSS and SDE will be applied in the present paper in order to give an answer to the arising problem of the new mobility of the future, providing for a new innovative urban means, matching the different characteristics of an hoverboard and of a kick-scooter. The output of the study, described along the paper, is the adaptability of the abovementioned methodologies and the proposal of a new product concept for the scopes illustrated.

Keywords: BENCHMARKING | DFSS | IDeS | QFD | SDE

Abstract: The present paper is about a family car project that starts from a study of the characteristics of the type of car taken into consideration and from an analysis of the environment carried out through an historical research on the models on the market from the 30s to the mid-90s, and their classification. The market analysis was carried out by answering six questions from the QFD and by developing the tables of relative importance and interrelation through which the most important and the most independent requirements to be attributed to the innovative family project were obtained. The competitor analysis was made through a research on the models currently on the market, the development of the benchmarking, and the what/how matrix from which the final requirements and project objectives were determined. The brand was selected, the budget was drawn up over a 12-month period and the car’s product architecture was defined. The SDE was carried out through an aesthetic analysis of the existing models, the sketches for each type of style and the selection of the final sketches. The development of the product, instead, consisted in the prototyping of a 1:18 scale model of the car through 3D printing.

Keywords: 3D Printing | CAD | QFD | Rendering | SDE

Abstract: Since 3D printing was developed, it became the most promising technique to speed up prototyping in a wide variety of areas across the industry. Rapid prototyping allows the medical industry to customize the surgery procedures, thus predicting its result. Biomedical applications made by medical grade elastic thermoplastic polyurethane (TPU); a non-traditional plastic material which allows to obtain additional benefits in rapid 3D prototyping because of its flexibility and anti-bacteriological capabilities. The aim of this study is to assess the efficacy of TPU polymer, FDM objects sourced from CT scanned 3D surfaces for helping surgeons in preoperative planning and training for increasing environment perception, that is, geometry and feeling of the tissues, whilst performing standard procedures that require complex techniques and equipment. A research was performed to assess the physical and qualitative characteristics of TPU 3D developed objects, by developing a proper SWOT analysis against PLA, a widely used, and cost-effective option in FDM industry. Therefore, giving a proposition opposite to other known modern medical planning techniques and bringing out the benefits of the application of TPU-sourced, FDM parts on professional medical training. As a result, PLA is a reliable, wide-available process whilst TPU’s flexible capabilities improves realism in 3D printed parts. Surgical planning and training with rapid prototyping, would improve accurate medical prototyping for customized-procedures, by reducing surgery times, unnecessary tissue perforations and fewer healing complications; providing experience that other FDM materials like PLA cannot be reached.

Keywords: 3D Printing | 3D Scanner | QFD | Surgical Training | TPU

Abstract: This work aims to present the application of mechanical modeling software in three dimensions in the medical field, analyzing the procedures used by the engineer to support the orthopedic surgeon in preoperative planning. The first step of the procedure involves CT examinations in patients selected for surgery: DICOM images are managed in post-processing to obtain multiplanar reconstructions of the bone lesion to be treated. The files are then optimized, made shareable and imported into CREO's work platform; this is part of a family of CAD software products for mechanical design, developed by PTC, and is the fundamental application dedicated to parametric modeling. The result will be a faithful representation of the anatomical part both before and after surgical procedure, screening all the intermediate phases. The doctor will assess different lines of action according to the results, than he will communicate them to the engineer who, consequently, will correct and regenerate the model. The method finds its power in the dialogue between engineer and doctor: In complex cases closer collaboration is needed while, for the evaluation of less demanding injuries, the exam could be assigned as a remote project which, once completed, is returned to the medical facility of competence.

Keywords: 3D modeling | Computer aided | Parametric software | Preoperative planning | Surgical simulation

Abstract: Fused Deposition Modeling (FDM) 3D printing technology has widespread in a variety of scientific fields, since rapid prototyping and low-cost investments well meet flexibility of application. Mechanical engineering is taking an essential role in Orthopaedics and Traumatology. As a patient-specific approach and minimally invasive surgeries are progressively needed in today’s medical routines, highly-customized 3D printed devices and surgical instruments represent a milestone in medical equipment. Virtual preoperatory planning and computer aided surgical simulations (CASS) enhance 3D visualization of human anatomy, giving doctors full understanding of traumas and deformities. Custom cutting guides (CCGs) represent the cutting edge of patient-dedicated surgical routines, allowing for a sensible reduction of operative time and risk of human error. While maxillofacial surgery (MFS) has already adopted customized 3D printed tools, pediatric orthopaedics (PO) and general long bones surgery strive to put these devices into common practice. Limitations to a large-scale implementation rely on collaboration with the industrial world, as engineering and designing skills are inevitably demanded. Here displayed is the prototype for a femoral cutting guide designed for a pediatric application of the IOR - Rizzoli Orthopaedic Institute of Bologna. The device was printed in a High-Temperature PLA, supporting common steam heat sterilization and maintaining designed geometry.

Keywords: 3D printing | CAD surgery simulation | CT scan | Cutting guide | Orthopaedic reproduction model

Abstract: The present work is a case study about the application of the methodology named Stylistic Design Engineering (SDE), that is an approach to develop car design projects in the industrial world. For attending this goal, it was chosen the S-segment car products, category that identifies the sport car as today’s Lotus. The inspiration for the project started from the top model in the past years of the car manufacturer Audi, or the Audi Quattro (1980-1991). This model represented all the time the most advanced technology in the automotive world of the house, and the most important thing was the all-wheel drive, therefore with four-wheel drive. In the following pages will be illustrated the summary of the path that led to the final product following the “instructions” of SDE method.

Keywords: 3D Printing | QFD | SDE | Sportcar

Abstract: This work is the outcome of a partnership between the Department of Industrial Engineering of the University of Bologna and the Rizzoli Orthopedic Institute of Bologna. The aim of this collaboration is using medical engineering tools during orthopedic surgeries. This article focuses on the design and construction of a custom-made surgical guide for cubitus varus. The guides are special aids that allow surgeons to perform operations smoothly, to achieve the planned result and to reduce the risk of inaccuracy. They are obtained with an additive manufacturing process that starts from a 3D digital model of the patient's bone obtained from CT scans and allow designing patient-specific templates using specific software as the Creo Parametric CAD. For the proper functioning of the guide the internal shape must correspond to the external profile of the patient's bone. In this way, the tool obtained fits exactly to the bone and it is possible to direct the cutting during surgery in a very specific direction as identified in the preoperative planning phase.

Keywords: 3D Printing | Cutting guides | Pediatric Orthopedics | Surgery and Diagnostics

Abstract: In the present work the Stylistic Design Engineering (SDE), a structured engineering methodology developed to carry out car design projects, is applied to the creation of a new reliable and robust utility vehicle, also suitable for traveling in the countryside. In particular, the design project aimed at the possibility of launching a new Citroen 2CV that would maintain the lightness and reduced fuel consumption of the previous model but that would combine these characteristics with greater eco-sustainability, thanks to electric drive, and greater comfort for passengers. SDE consists of the following steps: (1) sketches; (2) 2D CAD drawings; (3) 3D CAD models; (4) 3D printed models (also referred to as styling models); (5) Optimization of maquettes through technical objectives. This project deals with the exterior restyling of the Citroen 2CV and was carried out using different technologies and design methodologies that will be further explained in detail, such as the Pininfarina method, the QFD (Quality Function Deployment) and the 6 Sigma method. The work was organized in different phases and in all these phases the quality methodologies mentioned above were used. At first the Citroen style was studied, a fundamental step to better understand the characteristics of the brand and also the main characteristics carried out over the years of the product's life. Subsequently, the freehand sketching phase was carried out, inspired by the considerations made in the previous study phase. This phase continued until a satisfactory form was found by analyzing and discarding the various proposals of the various types of style. Once the definitive proposal was chosen, the definitive three-dimensional shape was obtained and on it it was possible to evaluate proportions and dimensions, also thanks to the rendering software.

Keywords: Benchmarking Analysis | Car Design | Quality Function Deployment (QFD) | Stylistic Design Engineering (SDE) | Top Flop Analysis

Abstract: The life of industrial products is getting shorter due to the rapid evolution of technologies. Because of that, the creation of models that are interested in last part of the product’s life are becoming extremely relevant. In recent years, many investments have been made in the recycling of raw materials and the reuse of End-Of-Life (EOL) products in order to reduce the waste of resources. Strategies of Design for Environment (DfE) have been searched and, for this reason, the Design for Disassembly (DfD) has become a fundamental phase in the product life cycle with the subsequent creation of design techniques aimed precisely at disassembly. Using this methodology, the designer can study and plan the optimal sequence which should be based on countless factors and criteria because there is not a straightforward path or a single combination of operations to follow. This paper describes and compares multiple disassembly methods based on minimum disassembly time with reference to a worm gear reducer. In particular, the component was made entirely on CAD (SolidWorks) and the sequences were pplied in a virtual environment. In this way, it was possible to evaluate different algorithms and obtain the optimal disassembly sequence that minimize the overall disassembly time.

Keywords: CAD | Disassembly | Sequence | TMU | Virtual Reality

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: This work aims to present an in-house low-cost computer-aided simulation (CASS) process that was recently implemented in the preoperative planning of complex osteotomies for limb deformities in children. Five patients admitted to the Unit of Paediatric Orthopaedics and Traumatology from April 2018 to December 2019, for correcting congenital or post-traumatic limb deformities were included in the study. Three-dimensional (3D) digital models were generated from Computed Tomography (CT) scans, using free open-source software, and the surgery was planned and simulated starting from the 3D digital model. 3D printed sterilizable models were fabricated using a low-cost 3D printer, and animations of the operation were generated with the aim to accurately explain the operation to parents. All procedures were successfully planned using our CASS method and the 3D printed models were used during the operation, improving the understanding of the severely abnormal bony anatomy. The surgery was precisely reproduced according to CASS and the deformities were successfully corrected in four cases, while in one case, the intraoperative intentional undersizing of the bone osteotomy produced an incomplete correction of a congenital forearm deformity. Our study describes the application of a safe, effective, user-friendly, and low-cost CASS process in paediatric orthopaedics (PO) surgery. We are convinced that our study will stimulate the widespread adoption of this technological innovation in routine clinical practice for the treatment of rare congenital and post-traumatic limb deformities during childhood.

Keywords: 3D modeling | Computer aided | Osteotomy | Paediatric orthopaedics | Preoperative planning | Surgery | Surgical simulation

Abstract: "Innovation activities" means all the scientific, technological, organizational, financial and commercial steps aimed at implementing innovation. Some innovation activities are themselves innovative, others are not new, but they are necessary for the implementation of innovation, such as Research and Development not linked to a specific innovation. Innovation has a close reference to the economic market, that is to say with the users of the innovated product: if these are not sufficiently developed they are not able to understand it and appreciate it. Innovation, making the process better, generates greater competitiveness: it is the dream of something better that translates into general well-being. This work presents an innovative hybrid car's design, belonging to the E-segment. The choice of this segment is already innovative in its nature, as despite being currently in strong development, hybrid and electric engines are still little used for large sedans. The method we present in this paper for the car design is also innovative and is called Design for Six Sigma. It is a method used to develop new products, through the determination of customer and market needs and the transformation of these requests into the product generated.

Keywords: Automotive | Bench marking | Car | Design for six sigma | E-segment | Quality function deployment | Sedan

Abstract: This work is focused on the study of 3D prints applied in the orthopedic-pediatric field. The focus is therefore on all the processes that lead to obtaining 3D bone printing starting from the three-dimensional digital CAD model. Specifically, the case study concerns patients with flat foot pathology from tarsal synostosis. The final result of the printing process is a three-dimensional bone model reflecting the original anatomical structure. This is a useful tool for surgeons who can carry out a preventive analytical evaluation of the relative intervention methods. 3D printing can be useful both in the preoperative planning phase and during the operation. Depending on the case, it may be more convenient to use one material than another. For this reason, another goal set by this work concerns the study of materials used for 3D printing of bones.

Keywords: 3D Printing | Diagnostics | Pediatric Orthopedics | Surgery

Abstract: The present work shows how 3D models extracted from a computerised tomography (CT) scan can be processed to be 3D printed into 1:1 orthopedic scale models, which find unquestionable utility in pre-operative surgical planning. Relying on the CAT-CAD methodology, which produces a 3D surface called “mesh” from diagnostic images of body parts, the CAD-AM process elaborates a volumetric bone model which a cost-efficient FDM printer can work with. The suitable materials for these applications are PLA polymers, due to their thermo-mechanical properties, affordability and ecological sustainability; these anatomic 3D printed models allows surgeons to accurately see bones injuries and trauma, resulting in a minimisation of risk and a much more flowing doctor-patient communication. Furthermore these 3D printed objects can be manufactured with specific density in order to simulate bone tissues, resulting in a useful tool through which experienced surgeons can pass on their knowledge to medical students at a very reasonable cost, overcoming the glaring limitations of two-dimensional images provided by CT scans. Here represented is a 3D printed 1:1 scale model of a femur donated to the Bone Bank of IOR-Rizzoli Orthopaedic Institute in Bologna.

Keywords: CT scan | FDM printer | Orthopaedic Reproduction Model | PLA polymer

Abstract: This paper presents a a novel alghorithm of diagnosis and treatment of rigid flatfoot due to tarsal coalition. It introduces a workflow based on 3D printed models, that ensures more efficiency, not only by reducing costs and time, but also by improving procedures in the preoperative clinical phase. Since this paper concerns the development of a new methodology that integrates both engineering and medical fields, it highlights symmetry. An economic comparison is made between the traditional method and the innovative one; the results demonstrate a reduction in costs with the latter. The current, traditional method faces critical issues in diagnosing the pathologies of a limb (such as the foot) and taking decisions for further treatment of the same limb. The proposed alternative methodology thus uses new technologies that are part of the traditional workflow, only replacing the most obsolete ones. In fact, it is increasingly becoming necessary to introduce new technologies in orthopedics, as in other areas of medicine, to offer improved healthcare services for patients. Similar clinical treatments can be performed using the aforementioned technologies, offering greater effectiveness, more simplicity of approach, shorter times, and lower costs. An important technology that fits into this proposed methodology is 3D printing.

Keywords: 3D printing | Diagnostics | Orthopaedics | Paediatry | Surgery

Abstract: In this paper, we present a solution for the photorealistic ambient light render of holograms into dynamic real scenes, in augmented reality applications. Based on Microsoft HoloLens, we achieved this result with an Image Base Lighting (IBL) approach. The real-time image capturing that has been designed is able to automatically locate and position directional lights providing the right illumination to the holograms. We also implemented a negative "shadow drawing" shader that contributes to the final photorealistic and immersive effect of holograms in real life. The main focus of this research was to achieve a superior photorealism through the combination of real-time lights placement and negative "shadow drawing" shader. The solution was evaluated in various Augmented Reality case studies, from classical ones (using Vuforia Toolkit) to innovative applications (using HoloLens).

Keywords: Augmented reality | Holographic shadow | Image processing | Light mapping | Rendering techniques

Abstract: This paper presents the application of a low-cost 3D printing technology in pre-operative planning and intra-operative decision-making. Starting from Computed Tomography (CT) scans, we were able to reconstruct a 3D model of the area of interest with a very simple and rapid workflow, using open-source software and an entry level 3D printer. The use of High Temperature Poly-Lactic Acid (HTPLA) by ProtoPasta allowed fabricating sterilizable models, which could be used within the surgical field. We believe that our method is an appealing alternative to high-end commercial products, being superior for cost and speed of production. It could be advantageous especially for small and less affluent hospitals that could produce customized sterilizable tools with little investment and high versatility.

Keywords: 3D printing | Computed tomography | Diagnostic imaging | Mesh reconstruction | Rapid prototyping | Surgical planning