Abstract: Additive manufacturing (AM) of load-bearing metal implants allows sustainable production of personalized implants with complex shapes and inner architectures. Implants must meet strict requirements to not harm patients, and production technique must certify their performance. Available materials, many production parameters and implant personalization on patient's needs represent limits of AM. Layer-by-layer material deposition and repeated thermal cycles typical of AM may also cause discontinuities between layers affecting implant mechanical features, and its match to the host body. In this paper the mechanical challenges that AM must overcome to replace traditional manufacturing techniques are discussed, in order to better understand whether AM has to be limited to implant personalization for exceptional cases.

Keywords: Additive manufacturing | Conventional manufacturing | Geometric accuracy | Implants | Mechanical properties

Abstract: Additive manufacturing (AM) permits sustainable production of personalized load-bearing metal implants with complex structures. Regulations prescribe that implants have to meet strict requirements to not harm patients, and production technique should allow the certification of their performance. Process, materials, operating parameters, and customization to patient's needs could limit AM. Layer-by-layer material deposition and repeated thermal cycles may make outer surface of AM implants chemically and physically uneven and rough, eliciting biological response of host tissue and hindering therapeutic success. In this paper, we discuss the clinical challenges that AM must overcome to replace traditional techniques in implant and prostheses design.

Keywords: Additive manufacturing | Clinical performance | Conventional manufacturing | Implants | Surface properties

Abstract: Introduction: We report the development and preliminary evaluation of a novel dynamic bioreactor to culture ovarian cortical tissue strips that leverages tissue response to enhanced oxygen transport and adequate mechanical stimulation. In vitro multistep ovarian tissue static culture followed by mature oocyte generation, fertilization, and embryo transfer promises to use the reserve of dormant follicles. Unfortunately, static in vitro culture of ovarian tissue does not promote development of primordial to secondary follicles or sustain follicle viability and thereby limits the number of obtainable mature oocytes. Enhancing oxygen transport to and exerting mechanical stimulation on ovarian tissue in a dynamic bioreactor may more closely mimic the physiological microenvironment and thus promote follicle activation, development, and viability. Materials and Methods: The most transport-effective dynamic bioreactor design was modified using 3D models of medium and oxygen transport to maximize strip perifusion and apply tissue fluid dynamic shear stresses and direct compressive strains to elicit tissue response. Prototypes of the final bioreactor design were manufactured with materials of varying cytocompatibility and assessed by testing the effect of leachables on sperm motility. Effectiveness of the bioreactor culture was characterized against static controls by culturing fresh bovine ovarian tissue strips for 7 days at 4.8 × 10−5 m/s medium filtration flux in air at −15% maximal total compressive strain and by assessing follicle development, health, and viability. Results and Conclusions: Culture in dynamic bioreactors promoted effective oxygen transport to tissues and stimulated tissues with strains and fluid dynamic shear stresses that, although non-uniform, significantly influenced tissue metabolism. Tissue strip culture in bioreactors made of cytocompatible polypropylene preserved follicle viability and promoted follicle development better than static culture, less so in bioreactors made of cytotoxic ABS-like resin.

Keywords: bioreactor | dynamic culture | fluid dynamic stimulation | mechanical stimulation | ovarian tissue | oxygen transport

Abstract: Cranial reconstructions are essential for restoring both function and aesthetics in patients with craniofacial deformities or traumatic injuries. Titanium prostheses have gained popularity due to their biocompatibility, strength, and corrosion resistance. The use of Superplastic Forming (SPF) and Single Point Incremental Forming (SPIF) techniques to create titanium prostheses, specifically designed for cranial reconstructions was investigated in an ovine model through microtomographic and histomorphometric analyses. The results obtained from the explanted specimens revealed significant variations in bone volume, trabecular thickness, spacing, and number across different regions of interest (VOIs or ROIs). Those regions next to the center of the cranial defect exhibited the most immature bone, characterized by higher porosity, decreased trabecular thickness, and wider trabecular spacing. Dynamic histomorphometry demonstrated differences in the mineralizing surface to bone surface ratio (MS/BS) and mineral apposition rate (MAR) depending on the timing of fluorochrome administration. A layer of connective tissue separated the prosthesis and the bone tissue. Overall, the study provided validation for the use of cranial prostheses made using SPF and SPIF techniques, offering insights into the processes of bone formation and remodeling in the implanted ovine model.

Abstract: Radial flow packed-bed bioreactors (rPBBs) overcome the transport limitations of static and axial-flow perfusion bioreactors and enable development of clinical-scale bioengineered tissues. We developed criteria to design rPBBs with uniform medium radial flux distribution along bioreactor length ensuring uniform construct perfusion. We report a model-based analysis of the effect of non-uniform axial distribution of medium radial flux on pericellular concentration of oxygen and glucose. Albeit pseudo-homogeneous, the model predicts how medium flux, solutes transport and cellular consumption interact and determine the pericellular oxygen and glucose concentrations in the presence of pore transport resistance to design optimal axisymmetric rPBBs and enable control of pericellular environment. Thus, oxygen and glucose supply may match cell requirements as tissue matures. Flow and solute transport in bioreactor empty spaces and construct was described with Navier-Stokes and Darcy-Brinkman equations, and with convection–diffusion and convection–diffusion-reaction equations, respectively. Solute transport in construct accounted for Michaelian cellular consumption and bulk medium-to-cell surface oxygen transport resistance in terms of a transport-equivalent bed of Raschig rings. The effect of relevant dimensionless groups on pericellular and bulk solute concentrations was predicted under typical tissue engineering operation and evaluated against literature data for bone tissue engineering. Axial distribution of medium radial flux influenced the distribution of pericellular solutes concentration, more so at high cell metabolic activity. Increasing medium feed flow rates relieved non-uniform solute concentration distribution and decayed at cell surface for metabolic consumption, also starting from axially non-uniform radial flux distribution. Model predictions were obtained in runtimes compatible with on-line control strategies.

Keywords: Glucose | Model | Oxygen | Radial-flow packed-bed bioreactor | Tissue engineering | Transport

Abstract: In vitro ovarian cortical tissue culture, followed by culture of isolated secondary follicles, is a promising future option for production of mature oocytes. Although efforts have been made to improve the culture outcome by changing the medium composition, so far, most studies used static culture systems. Here we describe the outcome of 7 days cultures of bovine and human ovarian cortical tissue in a dynamic system using a novel perifusion bioreactor in comparison to static culture in conventional and/or gas permeable dishes. Findings show that dynamic culture significantly improves follicle quality and viability, percentage and health of secondary follicles, overall tissue health, and steroid secretion in both species. Model predictions suggest that such amelioration can be mediated by an enhanced oxygen availability and/or by fluid-mechanical shear stresses and solid compressive strains exerted on the tissue.

Abstract: Currently, the growing need for highly customized implants has become one of the key aspects to increase the life expectancy and reduce time and costs for prolonged hospitalizations due to premature failures of implanted prostheses. According to the literature, several technological solutions are considered suitable to achieve the necessary geometrical complexity, from the conventional subtractive approaches to the more innovative additive solutions. In the case of cranial prostheses, which must guarantee a very good fitting of the region surrounding the implant in order to minimize micromotions and reduce infections, the need of a product characterized by high geometrical complexity combined with both strength and limited weight, has pushed the research towards the adoption of manufacturing processes able to improve the product’s quality but being fast and flexible enough. The attention has been thus focused in this paper on sheet metal forming processes and, namely on the Single Point Incremental Forming (SPIF) and the Superplastic Forming (SPF). In particular, the complete procedure to design and produce titanium cranial prostheses for in vivo tests is described: starting from Digital Imaging and COmmunications in Medicine (DICOM) images of the ovine animal, the design was conducted and the production process simulated to evaluate the process parameters and the production set up. The forming characteristics of the prostheses were finally evaluated in terms of thickness distributions and part’s geometry. The effectiveness of the proposed methodology has been finally assessed through the implantation of the manufactured prostheses in sheep.

Keywords: Custom prosthesis | In vivo tests | Single point incremental forming | Superplastic forming | Ti‐6Al‐4V ELI

Abstract: Product design is an activity that must be supported by information in order to allow designers to conceive solutions to real problems that do not introduce further issues, first of all, environmental concerns. Axiomatic design is an approach that provides the possibility to check whether a design solution is functionally valid and it can also be extended considering eco-design elements. In a synthetic representation of 1D and 2D arrays, it can inform designers about the level of sustainability of the product on which they have been working on since the first phase of design when they start to embody functionalities by introducing real components, and first assemblies appear. To achieve this task, the domains considered in the original formulation of Axiomatic Design have been revised, and a new domain has been introduced. This allows designers to take into account all the phases of product life and improve design solutions to avoid introducing structures, components, and functionalities that might be the cause of environmental problems. The paper describes such new mapping among domains and applies it to design a daily life device. The contents of the new data structure will be presented and discussed.

Keywords: Axiomatic design | Design matrix | Mapping among domains | Sustainability matrix | Sustainable products design

Abstract: ASME Y14.5 and Y14.43 standards share the task to define a coherent context in which geometric tolerances may find a rational approach. Even ASME Y14.5 defines the rules, meanings, and descriptions of geometric tolerances, ASME Y14.43 applies them aiming to design and build functional gages able to check if the geometric characteristics, assigned on a drawing, have been reached in a physical component. Many of the assumptions given in the ASME Y14.5 may be understood only when the design of a functional gage is approached. The need to build such kind of device is strictly connected with the need of industry that requires best-practices able to check geometric characteristics of products in a short time. The basic elements of ASME Y14.43 are summarized in the paper and a functional gage, taken from the edition of 2011, is elaborated and discussed. The root of the American standards has been associated with the philosophical school of pragmatism in which more attention is paid to practical examples and how every theoretical conceivement must be verified by scientific experimentation.

Keywords: Functional gages | Geometric dimensioning and tolerancing | Pragmatism

Abstract: Analyzing an assembly and recognizing how the components can mate with each other in order to satisfy the functionality for which they have been designed is not a trivial task. Teaching such a problem to engineering students requires they are familiar with a set of components and how much larger or thin can be the errors intrinsically related to the technologies employed in their production. A set of steps are necessary to reasoning about the right identification of a chain of dimensions that influences a functionality. Then can be useful to have a table where collect the data, especially when the number of parts is relevant. The paper presents a new format for the table that can be used in all kinds of problems that may occur in design: analysis, analysis with constraints, and synthesis. The way how to employ such a table and the steps to solve each problem is discussed with known examples.

Keywords: Modeling | Tolerance analysis and synthesis | Tolerance stack-up

Abstract: Additive Manufacturing technologies have opened new perspectives for the realization of tissue and organs substitutes. The main advantages come from the possibility of using the same technology to produce artificial or biological substitutes in a wide range of outer shapes and inner reticular architectures, which may pave the way to their use to produce personalized substitutes. Additive manufacturing technologies are based on layer-by-layer material fusion and deposition. As such, they have intrinsic limitations which may hinder the possibility to produce substitutes that meet the requirements for safe clinical use. As an example, discontinuities between layers may make the outer surface of a substitute significantly uneven, rough, and may even weaken the substitute mechanical properties in such an aggressive environment as the human body. Moreover, repeated thermal cycles (fusion and solidification) drastically limit the choice of materials which can be used. Finally, the outcome of the production technology is affected by many variables that it is not trivial to control to deliver the necessary quality and repeatability of the production process for medical applications. Indeed, the surface roughness of an implantable prosthesis or organ substitute is key to modulate cell adhesion and the susceptibility to chemical attack by body fluids. Structural strength is a mandatory requirement for load-bearing prostheses (e.g., orthopedic and dental prostheses). Materials for biomedical applications must not only be 3D printable, but also biocompatible and/or possibly have to promote cells growth and to prevent inflammatory reactions. The performance of artificial, bio artificial and tissue-engineered organs needs also to be certified and guaranteed, a rather difficult task to define for devices which may be unique, being tailored on the specific needs of the patient. In this paper, it will be discussed whether this technology is sufficiently mature to replace more traditional techniques or, alternatively, whether it should be limited to a restricted range of emergency applications until the existing relevant technological gaps are filled.

Keywords: 3D printing | additive manufaturing | artificial organs | clinical | corrosion | fatigue | prostheses | strength | surface | surgical guides | wear

Abstract: In the last years, the precision and personalized medicine is pushing the biomedical research efforts towards the direction of implant surgery requiring only 1-step approach: this goal has been achieved after the introduction of resorbable implants. The resorbable prosthetic support is indicated for temporary prosthetic applications, such as bone fractures fixation, or all those conditions usually treated with metal implants then removed with a second surgery, just after the healing of the bone defect. Biodegradable, bioactive and customizable implants for the treatment of bone fractures, both efficient in bearing the functional loads, and showing good biocompatibility and degradation properties matching the bone tissue healing, are still lacking. These premises have led to consider Magnesium (Mg) and its alloys as very promising candidates for the development of temporary, resorbable implants. However, the very high corrosion rate of Mg is the main problem, not yet solved. The material needs to be properly treated/coated, as well as manufactured, in order to design the most suitable duration of the temporary prosthesis permanence in situ. An innovative and interdisciplinary approach has been developed within the M.Era-Net ISIDE project and it is here briefly detailed with a special focus on the highlighted application fields.

Keywords: customade prostesis | Mg alloys | Reabsorbable implants

Abstract: Considering reviewers' opinions on the paper, presented at EPDE2021, in which the data were not sufficient to compare different cohorts, now we are able to answer if there have been differences in students' assessments, based on some questions of the academic survey on didactics, comparing answers for courses held pre-and-during Covid19 pandemic. In 2020 every educational institution moved their didactics toward an online platform. Every course had to introduce and experiment with new forms of didactics that prevent in-person events, either in lectures or laboratory. Courses of design traditionally require a strict relation between student-instructor and student-student. The need to operate by moving the contact to an online connection creates, at the beginning of the period, a lot of distrust among teachers of such courses. The “Machine Drawing” course is one of these. Briefly recalling how the courses have been revised, with the employment of a communication platform like Teams®, the answers, given by students, are collected and the differences along the time are highlighted. Three academic years have been considered: 2017-2018, 2019-2020, and 2020-2021. A further correlation has been made considering different didactics and the global efficiency of the course in terms of abandonment, number of successes (number of people that pass the exam), and the effects on the grades (marks) obtained. Reflecting on such data, a new consideration has been done on the methodologies that can still continue to be used in the future when the explicit problem of pandemic emergency does will not influence anymore the traditional way of teaching.

Keywords: Online didactics | students' assessments | teaching quality improvement

Abstract: Sketching is becoming an irrelevant activity of engineering studies. The availability of many software that aids designers in all phases of design, not only analytic but synthetic, push technicians, designers to use such tools, giving up the employment of a simple pencil and eraser on a sheet of paper. The productivity of software tools is obliged to speed and manage the whole design process; even freehand sketching remains the fundamental means to communicate the first ideas immediately. During Brainwriting sessions, the ability to explain by sketches first elaborations of a possible solution, that must be understood by co-designers, is the first step that allows more fruitful discussion and immediate adjustment towards a quick embodiment of valid proposals. The paper describes how such techniques has been introduced in the mechanical engineering curriculum. The case of study reports the experience of the Brainwriting online, which has been tested during lockdown due to the pandemic disease of COVID-19. Further in the paper it is suggested a new interpretation of the de Saussure general linguistic studies, in term of a communication that is associated to a drawing.

Keywords: Brainwriting | Communicate design intent | Interactive design | Product design | Semiology | Sketching

Abstract: Since Learning Management Systems (LMS) appeared some 20 years ago, their experimentation grew slowly, compared with the explosion that occurred after the Covid-19 emergency. Due to the closure of schools and universities worldwide, every educational institution and their teachers had to move towards the usage of LMSs for Online Distance Learning (ODL). This obliged the teachers to quickly familiarize with such kind of didactics and every kind of course faced these new opportunities. Machine Drawing is a course that requires much interaction between teachers and students and may not exploit validly many modalities invented in LMS. This paper presents the experiences done implementing online didactics, trying to apply all the online tools to the traditional way of teaching. Mainly laboratory activities, made online, must reproduce the interaction made in-person. Nevertheless, online connections opened new ways to try stricter relationships between the teacher and those students, who have less skill, even shyness, and then may accumulate delays. Differentiating the way in which didactics (lecture and laboratory) may be delivered, some traditional techniques have been improved. Employment the video recording of all activities done has given students the opportunity to repeat the more delicate steps of some topics. The check online of designs and elaborations by instructors allows students to be more concentrated on explanation, which may be done collectively or singularly. Comparing the results of exams before and after online didactics revealed that the number of students that passed the exam and the average of reached grade grew significantly.

Keywords: Machine drawing | Online classroom | Virtual class

Abstract: Teaching product design is not a trivisal task. Considering the experience done along 20 years of teaching at master level class in mechanical engineering it is possible to take stock. The model followed is Project-Based Learning and this method can be licensed as the model that gives greater satisfaction to all attendees. Students give high score to the survey organized by university at the end of the course to assess didactic validity. Also, teachers have many stimuli when discussing with students the activities proposed. The course is based on the development of an industrial product that solves a problem, eventually posed by industry or emerged by customers. Based on the course schedule, the different phases of product development put in evidence the steps that require divergent thinking and those where it is necessary to employ convergent thinking. A case study allows explaining all the phases of product design.

Keywords: Integration of design methodologies | Product design and development | Project-Based Learning | Project-Based Pedagogy

Abstract: Mechanical and Management Engineering are some of the stakeholders involved in product development, with different competencies. They must share the responsibility for best solution identification to accordingly answer the customer needs and to authorize the production of products that can have success with a positive economic return. Higher education curricula should prepare such professionals, and this is the reason because courses of product design are proposed to such classes. Even the programmes of the corresponding courses are necessarily different the part related to concept generation is similar. The work aims is to identify analogies and differences between the classes of Mechanical Engineering and Management Engineering, both in the way of leading the generation of concepts and in how the concepts generated have eventually reached the goals of innovation. BrainWriting is a method that can allow students to be productive in concept generation and is based on the two steps of sketching and gallery. This ability must be conjointly employed with the functional study of the problem to be solved. These aspects must be learned by students to avoid fixation, the inconvenience to repeat indefinitely only what is already known. The design alternatives generated by teams of students will be assessed by teachers and experts in the field, following the method proposed by Shah. After such classification, further comparison between the two classes will be done to identify the aspects of the cultural imprinting of such future professionals.

Keywords: BrainWriting | comparison between different classes | creativity and innovation | creativity assessment | Product design education

Abstract: The paper discusses the process that leads to choosing a modular building system and how this has suggested a framework to make the right decision in clarifying the task and in generating and selecting new concepts. After illustrating the genesis of the need to build in a modular way, attention shifts to the criteria for evaluating the characteristics of modular buildings. The evaluation criteria were identified and sorted by category and, after an assessment of what already exists on the market and in literature, the guidelines for the design of a new modular building system were provided. The paper also illustrates some conceptual solutions that have arisen from the application of the identified criteria.

Keywords: Concept assessment | Concept generation | MCDA | Product assessment | Sustainable modular buildings

Abstract: The first phases of designing an industrial product are those in which creativity has the predominant weight in all the design process. Teaching to be creative is extremely complex and ambiguous, given the elusiveness of the mechanisms that guide it. In this work, the process of generating concepts has been observed during the laboratory of a dyad workgroup of master’s degree students in mechanical engineering in a course of Product Design and Development. Starting from a standard session of the 635 method (Brainwriting) it has been observed how the concepts have evolved in a continuous Brainwriting developed in five steps, between feared and almost manifested moments of fixation and exhaustion, towards increasingly mature and conscious solutions, despite the inexperience of the team members. Some aspects have been highlighted on the rotation mechanism of the different Brainwriting sessions and how this has contributed to concepts development; therefore a framework of a three-step Brainwriting session is proposed, which takes inspiration from this experience and those performed of past years.

Keywords: 635 method | Brainwriting | Concept generation | Continuous Brainwriting

Abstract: ANOVA is currently employed in association with the Robust Design in order to discover the parameters most influencing a particular performance of a device in the phase of development. Such relation has been studied for many times and literature is abundant. The peculiar nature of the Taguchi Method with the employment of orthogonal arrays introduces new elements in the investigation of the most influencing parameters. Considering that the plan of the experiment is organized on the base of level parameters combination orthogonal and balanced, ANOVA can be applied to each parameter individually and this gives new insight on the occurrence of noises in correspondence of some levels parameter. The paper analyses this kind of relation, reproducing an example from literature and discussing how ANOVA can be employed in such a study. Robust Design is an extraordinary method to be used in product development with the experiments simulated from CAE analyses. In this context, more conscious employment of such methodologies can aid in managing and organizing the study and experimentation on new products or processes. In another section a second example from the authors is re-proposed and some new insights are shown.

Keywords: ANOVA | Robust Design | Taguchi Method

Abstract: Background: Autotransplantation of cryopreserved ovarian tissue is currently the main option to preserve fertility for cancer patients. To avoid cancer cell reintroduction at transplantation, amulti-step culture systemhas been proposed to obtain fully competent oocytes for in vitro fertilization. Current in vitro systems are limited by the low number and health of secondary follicles produced during the first step culture of ovarian tissue fragments. To overcome such limitations, bioreactor designs have been proposed to enhance oxygen supply to the tissue, with inconsistent results. This retrospective study investigates, on theoretical grounds, whether the lack of a rational design of the proposed bioreactors prevented the full exploitation of follicle growth potential. Methods: Models describing oxygen transport in bioreactors and tissue were developed and used to predict oxygen availability inside ovarian tissue in the pertinent literature. Results: The proposed theoretical analysis suggests that a successful outcome is associated with enhanced oxygen availability in the cultured tissue in the considered bioreactor designs. This suggests that a rational approach to bioreactor design for ovarian tissue culture in vitro may help exploit tissue potential to support follicle growth.

Keywords: Design | In vitro culture | Ioreactor | Ovarian tissue | Oxygen | Transport

Abstract: Additive Manufacturing (AM) involves a set of production processes in which a layer-based material deposition approach to build parts is applied. These technologies are now extensively used in the industry in many cases as the main manufacturing process for making components with high shape complexity. The dimensional and geometric accuracy of the parts manufactured by means of AM are mostly determined by the specific type of additive process employed and the related process parameters. The part orientation in the build space is an important process parameter that has an influence on the stair-step effect and on the need of support structures and the subsequent post-processing refinements. In addition, the position of the part in the build volume may have an influence on the shape. These factors concur to the surface finish and to the dimensional and shape accuracy. In this paper, the flatness error on several surfaces, built on a test artefact ad hoc conceived, has been measured by means of a CMM-based setup in order to quantify the variation of the error in relation to: The orientation of the surfaces with respect to the platform, and the position of the part in the build volume of the AM machine. The test part has been produced by Direct Metal Laser Sintering (DMLS) process using the EOS Stainless Steel GP1. The test artifact has been designed with five flat surfaces at different angles with respect to the building platform. Two specimens were built in the same DMLS session with different position and alignment. The influence of the surface slope on the flatness error has been investigated. Flatness, 3D Roughness and orientation errors (parallelism, inclination, perpendicularity) have been measured and compared between both specimens.

Keywords: 3D surface roughness | Additive manufacturing | Flatness | Orientation error

Abstract: Underwater manipulation is a key technology for marine industries and exploration that can be efficiently adopted in other application fields, such as underwater archaeology, biological manipulation, scientific expedition, as well as offshore construction in the Oil and Gas industry. It is performed remotely by expert pilots thanks to the visual feedbacks provided by one or more cameras but without any information about the distance between the end-effector and the target. To this end, the paper presents a novel system based on a sensorized robotic arm, stereoscopic 3D perception and augmented reality visualization to support ROV's pilots in underwater manipulation tasks. The system, thanks to the adoption of an optical-stereo camera, provides a visual feedback of the underwater scene on which a depth map of the underwater workspace is augmented on. In particular, combining the kinematics of the robotic arm and the standard photogrammetric model of the stereo camera, it is possible to generate a depth map that shows to the pilots the distances of the surface of the scene objects from the end-effector's pose. Experimental tests carried out in the context of the CoMAS (In-situ conservation planning of Underwater Archaeological Artefacts) project have demonstrated the effectiveness of the proposed system.

Keywords: Augmented reality | Forward kinematics | Optical-stereo camera | Underwater manipulation

Abstract: The use of composite structures is increasing constantly in the last years, pushed by advantages of reduced weight and high strength. Moreover, the recent scenario points out a great attention on thermoplastic matrix composites due to their intrinsic recyclability as well for their possibility to re-use and re-manufacturing. However, the adoption of these materials can be further appreciated considering the secondary material workability as far as by demonstrating the possibility to re-manufacture the thermoplastic composite. The proposed work presents an experimental analysis carried out to investigate the downstream workability of a thermoplastic composite by one of the most versatile and flexible process. Glass fiber reinforced Polyamide 6 is the investigated material and the Single Point Incremental Forming is the implemented manufacturing approach. Since the composite matrix is characterized by a glass transition temperature higher than 50 °C, an external heating source has been necessary to perform the process in “hot” conditions. The process feasibility was fully demonstrated as well as the same was optimized in order to derive proper guidelines that can drive the process designer in the method star-up.

Keywords: Downstream process | Short glass-fibers | SPIF | Thermoplastic composite

Abstract: In the present work, sheet-forming processes, i.e. super plastic forming and single-point incremental forming, have been adopted for the manufacturing of custom prostheses, instead of subtractive and additive techniques that are time- and cost-consuming for a single-piece production. Regarding concerns of the material, three different titanium alloys were used: pure titanium and two grades of the alloy Ti-6Al-4V (the standard one and the extra low interstitial one). Since no standard protocol exists to assess the mechanical performance of cranial implants, an experimental procedure has been designed and used in this work for producing polymethylmethacrylate supports, on which the cranial prostheses were firmly connected and subjected to impact puncture tests (drop tests). An experimental campaign could thus be conducted to investigate the effect on the mechanical response of (a) the titanium alloy, (b) the initial blank thickness and (c) the manufacturing process. Drop tests, carried out according to the proposed procedure, have shown no failure of the prostheses, neither in the area of the impact nor in the anchoring region and have revealed that, irrespective of the adopted manufacturing process, which does not alter the material, the amount of energy absorbed by the implants is always larger than 70%.

Keywords: Drop test | Pure titanium | SPF | SPIF | Ti-6Al-4V | Ti-6Al-4V-ELI

Abstract: The Taguchi method is widely employed in several fields to manage and improve processes. It is interesting that it could be used during product development, considering it as the basic element to quantify the uncertainty of the device performance prediction. During product design, when many design aspects still must be understood by the design team, it is necessary to apply interactive approaches in order to simulate the behaviour of the device, employing CAx tools. Basically it is important to identify the most suitable “loss function” that can be associated with the characteristic function. In order to plane the investigation, the device under development ought to be described in term of the Design Matrix of Axiomatic Design, allowing the designer to characterize the relationship among the functional requirements and the corresponding design parameters. The nature of this relationship, generally not known a priori, can be revealed by the employment of the Taguchi method, once a suitable Objective Function has been chosen and the noise factors are identified. Analysing the performance of a device in a simulation of its behaviour in several operational conditions allows designers to discover whether there are correspondences or contradictions among design parameters. This can be synthetically said a robust design process. In order to enhance these aspects a design of experiment must be planned. The weak point of the procedure consists in the correct choice of the function that characterizes the device behaviour. Considering the wide academic debate on this point, the paper proposes a unique Noise Reduction function to be used in conjunction with all types of “loss function”. The Design Matrix can be checked and its nature can suggest the validity of the product under development and discover contradiction. The paper discusses an interactive procedure able to integrate the Taguchi method and the axiomatic approach.

Keywords: Axiomatic design | Design matrix | Noise reduction | Robust design | Taguchi method

Abstract: Humour may improve performance in creative problem solving as demonstrated in various studies, although the mechanisms underlying this phenomenon are still unclear. In this work the mechanisms of how humour facilitates creative problem solving during the conceptual phase of product design will be investigated. From the educational point of view all the activities that tend to reduce fixation during conceptual design are welcome, because students without specific experiences in work group and in generating original ideas reproduce always what is already known. In order to study the impact of humorous visual stimuli on creativity an experiment was performed. A sample of students of a MSc class in Management Engineering was divided into two sets and engaged to generate ideas concerning benches and shoe racks by Brainwriting (635 method) in two different ways: without stimulus and with stimulus. Three experts evaluated the concepts proposed in the generation phase and the Torrance Test of Creative Thinking (TTCT) was used to measure creativity. A correlation analysis among the different assessments made by evaluators was performed. The interquartile distance method was used to identify and delete the extreme and abnormal values. Finally, a sensitivity analysis was used in order to demonstrate that even changing the TTCT criteria weights the experiment outcome does not vary. The results obtained in this study shows that the concepts obtained using Brainwriting combined with humorous visual stimulation reach better creativity scores than those obtained without stimulation. Lastly, some hypotheses are suggested in order to explain some seemingly contradictory outcomes.

Keywords: Brainwriting | Creative Thinking | Creativity | Humour | Torrance Test of Creative Thinking

Abstract: The paper presents a description of a methodology to accurately estimate the natural frequencies of a hybrid metal-composite gear, where the web is made of a polymer matrix reinforced with two-dimensional (2D) triaxial braided fabrics. The proposed approach is based on a multi-scale composite modeling starting from evaluation of homogenized material properties of the gear web at the meso-scale for a subsequent FE-based modal analysis. For this purpose, the mechanical behavior of a single Repetitive Unit Cell (RUC) at the meso-scale is analyzed with a FE procedure which takes into account the interweaving and cross-section geometry of the yarns, volume fraction and local fiber orientation. It is shown that the described modeling strategy allows to predict gear's natural frequencies that are close to the experimental results. Significant accuracy enhancement is achieved with respect to the model in which the web material is considered as perfectly isotropic.

Keywords: Hybrid gears | Mechanical transmissions | Modal analysis | Multi-scale modeling | Triaxial braided fabrics

Abstract: The article presents a model to support designers and stakeholders when selecting the best product concepts, from among those in the course of development, assessing them from the sustainability point of view. The main aim of the article is to give the designer a road map, by which to collect and organize data, perform environmental analysis and compare different design alternatives, before the embodiment phase is completed. The model integrates different approaches: the use of a simplified life-cycle assessment to assess concepts when the information is poor or rough, performing the evaluation according to a set of environmental indicators; the employment of an augmented version of a design structure matrix, used to manage product components and functionalities; the use of a multi-criteria decision-making method to compare the environmental characteristics of design alternatives and a Pareto approach to select the most promising concepts. Finally, the design alternatives are expressed in terms of three dimensionless coordinates related to material wastes (α), energy dissipation (β) and environmental characteristics (γ) of the concept and are positioned in a three-dimensional environmental efficiency space to allow designers to visualize the position of each concept solution. The employment of an aggregate objective function and its geometric interpretation in the environmental efficiency space allows the designer to have a deeper knowledge of the choices to be made and how these can be taken more consciously. Furthermore, this final step can help designers and stakeholders in their reasoning about the environmental potentialities and drawbacks of the products in the phase of development. The whole model is applied to a case study where a group of five concepts of orange juicers are analysed and all the steps of the model are described in detail and discussed.

Keywords: design structure matrix | environmental assessment | environmental indicators | multi-criteria decision-making methods | product design

Abstract: Titanium and its alloys are widely used in cranioplasty because they are biocompatible with excellent mechanical properties and favor the osseointegration with the bone. However, when Titanium alloys have to be worked several problems occurred from a manufacturing point of view: the standard procedure for obtaining Titanium prostheses is represented by the machining processes, which result time and cost consuming. The aim of this research consist to introduce alternative flexible sheet forming processes, i.e. Super Plastic Forming (SPF) and Single Point Incremental Forming (SPIF), for the manufacturing of patient-oriented titanium prostheses. The research activities have already highlighted the potentiality of the investigated forming processes that can be alternatively used taking into account both the damage morphology and the need of urgency operation. In the present work, the way of manufacturing the Ti prostheses by SPF and SPIF is described. A comparative analysis has been performed, thus highlighting the peculiarities of the investigated processes and the prostheses feasibility.

Keywords: Single Point Incremental Forming | Super Plastic Forming | Titanium alloy

Abstract: The paper discusses the problem of the correct identification of the Objective Function and the associated SNR function that designers must choose when employing the Taguchi method in product design, considering this step as the basic element to quantify the uncertainty of the device performance prediction. During product design, when many design aspects must still be understood by the design team, it is important to identify the most suitable “loss function” that can be associated with the characteristic function. The second step considers the variability of the characteristic function. The Taguchi method considers many Signal to Noise Ratio functions whereas in the paper the use of a unique function is suggested for all kinds of loss function. The discussion is argued in the context of so-called parameter design, with the perspective of identifying the best ranges of variation of the parameters that designers have identified as influential on the characteristic function, and also to adjust those ranges in order to obtain twofold results: reduce Bias between the mean value of the characteristic function response and the target value; obtain less variability of the characteristic function. The discussion of a case of study will point out the approach and the use of a unique Noise Reduction function.

Keywords: Loss Function | Noise Reduction | Signal to Noise ratio | Taguchi method

Abstract: This paper describes a part of the contribution of the CoMAS project (“In situ conservation planning of Underwater Archaeological Artifacts”), funded by the Italian Ministry of Education, Universities and Research (MIUR), and run by a partnership of private companies and public research centers. The CoMAS project aims at the development of new materials, techniques and tools for the documentation, conservation and restoration of underwater archaeological sites in their natural environment. This paper details the results achieved during the project in the development of an innovative electric tool, which can efficiently support the restorers’ work in their activities aimed to preserve the underwater cultural heritage in its original location on the seafloor. In particular, the paper describes the different steps to develop an underwater electric cleaning brush, which is able to perform a first rough cleaning of the submerged archaeological structures by removing the loose deposits and the various marine organisms that reside on their surface. The peculiarity of this work consists in a user centred design approach that tries to overcome the lack of detailed users’ requirements and the lack of norms and guidelines for the ergonomic assessment of such kind of underwater tools. The proposed approach makes a wide use of additive manufacturing techniques for the realization and modification of prototypes to be employed for insitu experimentation conducted with the final users. The user tests have been addressed to collect data for supporting the iterative development of the prototype.

Keywords: Additive Manufacturing | Product Design | Underwater Applications | User centred design

Abstract: The present work collects some results of the three-years Research Program "BioForming", funded by the Italian Ministry of Education (MIUR) and aimed to investigate the possibility of using flexible sheet forming processes, i.e. Super Plastic Forming (SPF) and Single Point Incremental Forming (SPIF), for the manufacturing of patient-oriented titanium prostheses. The prosthetic implants used as case studies were from the skull; in particular, two different Ti alloys and geometries were considered: one to be produced in Ti-Gr23 by SPF and one to be produced in Ti-Gr2 by SPIF. Numerical simulations implementing material behaviours evaluated by characterization tests were conducted in order to design both the manufacturing processes. Subsequently, experimental tests were carried out implementing numerical results in terms of: (i) gas pressure profile able to determine a constant (and optimal) strain rate during the SPF process; (ii) tool path able to avoid rupture during the SPIF process. Post forming characteristics of the prostheses in terms of thickness distributions were measured and compared to data from simulations for validation purposes. A good correlation between numerical and experimental thickness distributions has been obtained; in addition, the possibility of successfully adopting both the SPF and the SPIF processes for the manufacturing of prostheses has been demonstrated.

Abstract: Cranioplasty is a surgery in which a prosthesis must be anchored on skull bone to repair a defect. One of the most used materials is the titanium. However, titanium prostheses could be made using the incremental sheet forming (ISF). Since titanium and bone are characterized by different Young modules, a detailed design of anchoring system is required to avoid cranial rupture. Aim of this study was to present a design procedure in order to identify the optimal anchoring system in case of craniofacial prostheses made with ISF. In detail, an optimization process and a predictive model for bone stress were used, choosing the numerical outputs of different FEM analyses as input data. The results indicate that our predictive and optimization models are accurate and, so, that this procedure could be very helpful for the prosthesis design, as demonstrated by the application of the procedure to a real case study.

Keywords: Anchoring system | Design procedure | Incremental sheet forming | Titanium prosthesis

Abstract: The production of prostheses is still not completely optimized, especially for those districts where both functional and aesthetic requirements have to be combined with the urgency of intervention. The prostheses manufactured by machining using CAD/CAM techniques represent the conventional way to obtain a "custom-made" part. However, the above-mentioned solutions are penalized by the too long manufacturing time. This limit can be overcome by using an innovative metal-forming process, i.e. the Incremental Sheet Forming (ISF), which also allows to obtain complex patient-specific geometries even if characterized by a lower precision compared to the conventional process. In this paper, alternative approaches to manufacture a skull prosthesis (i.e. conventional milling and ISF) are compared from technological and economical points of view.

Keywords: Anchoring system design | Prostheses modelling | Skull manufacturing

Abstract: Mapping among several domains allows different aspects of the design process to be put in relation. Considering that the DSM data structure is able to capture much information of a single part of the product development process, the DMM allows different domains to be linked. The first mapping matrix employed in the design process connects the functional and the physical domain. It describes how the functionalities are explained and by which elements. The Design Matrix of the Axiomatic Design approach is intrinsically a mapping matrix, and describes the relation between functional requirements and design parameters. It is a candidate to be part of the MDM data structure, being addressed to guide the solution to problems during the product design. The paper discusses the nature of the Design Matrix and compares it with the first DMM of the MDM process. On the basis of a case study differences and similarities are pointed out.

Keywords: Axiomatic design | Design matrix | DMM | DSM | MDM

Abstract: The contribution regards the surveying of two statues of famous contemporary sculptors that have been placed in the central zone of Cosenza, which has been transformed in an open air museum. To realize a 3-D representation of the museum, different methodologies have been used, based on classical surveying (total stations and GNSS), image data and range data. The increasing performances of the new models of Time Of Flight (T.O.F.) laser scanners allow to build accurate models also for medium-size objects; on the other hand, the recent techniques of 3D modeling enable the processing of large amount of data and the effective removal of noises. Thus, if an extreme accuracy is not required, one can think to use the T.O.F. laser scanner, also for the surveying of statues. For the acquisition of the surfaces of the statues, two different types of laser scanning have been used: the Leica Scan StationC10, based on Time Of Flight, and the Minolta VIVID 300 triangulation scanner. In the paper, the comparison between the results obtained by using the different techniques is described.

Keywords: 3D modelling | Augmented reality | City model | Cultural heritage | Laser scanning | Multiresolution | Representation

Abstract: The paper proposes an extension of the Design Structure Matrix to support designers in a rough sustainability evaluation of an industrial device in the early stage of its development. The methodology of assessment is based on an Augmented DSM (A-DSM), where the original DSM layout has been modified to allow developers to record information about product lifecycle and to manage the interactions of product components among them, towards other systems and with the environment outside. After a description of the novel matrix layout, a method is formalized. The proposed methodology will show that product evaluation is achieved by means of a combination of partial results that can be calculated already in conceptual phase: a set of environmental indicators and a couple of sustainability performance values. In accordance with this approach, the method is conceived as sustainability control panel useful to evaluate early environmental performance.

Keywords: A-DSM | Conceptual design | Early assessment | Functional analysis | Simplified LCA

Abstract: Incremental Forming is a flexible and innovative sheet metal forming process able to form complex shapes without the need of any expensive die. In this way, expensive fixtures are avoided obtaining a cheaper production, more advantageous for small production batches. Anyway, more than the process slowness, the geometrical accuracy represents the most important drawback today. In particular, two kinds of geometrical errors can be observed on a sheet component incrementally formed: the presence of elastic springback that modifies the imposed final depth, that "moves away" from the designed one, and the undesired bending effect of the sheet, which undergoes to the punch action. Several studies which tend to optimise the equipment and/or the tool path, in order to reduce the profile diverting, were executed. In this paper, an experimental investigation was carried out in order to test and introduce a new approach able to solve the above problem. More in detail, the test were executed applying an additional backdrawing phase, after the conventional negative deformation. Different testing conditions were evaluated during the experimental campaign and critically compared in the analysis. © Springer/ESAFORM 2009.

Keywords: Accuracy | Incremental sheet forming | Sheet metal forming

Abstract: Metallic foams are new materials mainly produced by expansion in a proper chamber and mainly characterized by internal voids: a material characterized by a very low density is obtained in this way. A lot of foamed components are commonly produced, directly by injecting a gas or foaming agent into molten metal inside a closed die. However, secondary operations on these materials can play an important role in order to enhance the foam production flexibility. From the above considerations, the deformation behaviour of an aluminium foam was investigated by compression tests. The study compares three different numerical analyses highlighting their points of strength and weakness in order to verify their applicability in process design. More in detail, two models based on the implicit formulation were investigated; in one case, the billet material was set as porous object with the material density which was calculated and updated as part of the simulation. The second implicit analysis, instead, was built using the plastic material formulation; the porosity, in this case, was physically created introducing voids within the workpiece. The latter simulation class was carried out through an explicit investigation; an efficient model construction was proposed introducing spherical surfaces connected each other with plans. Experimental data were used to validate the calculated results and a discussion concerning the three different numerical analyses was finally reported. © 2008 Elsevier Ltd. All rights reserved.

Abstract: A new device for the preparation of stoned olive oils, called SPIA, has been developed, aiming at fulfilling the targets of: (i) employing a less powered engine, (ii) reducing the size of the machine and (iii) reaching a good efficiency in terms of oil yields. Oleuropein expression was used as a biochemical parameter to distinguish stoned oils from oils produced by conventional milling systems. In vitro experiments performed by exposing oleuropein to pit enzymes, showed an exponential decay of the substrate. © 2007 Elsevier Ltd. All rights reserved.

Keywords: Isotope dilution | Oleuropein | Spring pitting apparatus | Stoned olive oil | Tandem mass spectrometry

Abstract: It is well known that the geometrical accuracy is a very relevant problem in Incremental Forming operations, since the material is not well sustained and, then, the elastic springback plays a significant role during the process. A number of researches are involved in the study of geometrical precision after the forming stage but considering the sheet clamped to the equipment. However, it is well known that material coupling is carried out after trimming, when it could change its shape after the new equilibrium. In the paper here addressed the above concept is kept in touch and a wide experimental campaign has been set-up in order to acquire experimental information on the effect of unclamping and trimming after incremental forming processes. The obtained results are able to suggest to the process designer some best practices which are accurately discussed in the paper.

Keywords: Incremental forming | Precision | Sheet metal forming

Abstract: In the conceptual design, a product can be viewed as a functional net, defined in the classic active verb-object way, by mean of functional elements and links associated to the flow of energy, material and signals and link of force. In order to assure the validity of the links at different levels, in the paper the graph theory is employed to check the suitability of a functional net, treated as a collection of sub graphs, each defined on a type of link. In order to verify the functional net it is necessary to identify each subnet, characterized by the same kind of link, and check each one using a set of formal relations that represent the feature of each link. Based on these relations a set of controls have been implemented for each subnet.

Keywords: Design process | Doubt based system | Functional net | Graph theory

Abstract: This paper presents an innovative application of Augmented Reality (AR) techniques in the field of industrial engineering in which the user explores data from numerical simulations or the results of measurements and experiments, superimposed to the real object that they refer to. The user observes the object through a tablet PC, used as a video see-through handheld display. Data are visualized superimposed to the real object that represents a spatial reference relative to which the user can refer to, so the exploration is more natural compared to a traditional visualization software. Moreover, we have developed a new framework, called VTK4AR, that provides a set of useful software classes for the rapid development of AR applications for scientific visualization. VTK4AR is built on top of VTK (an open source API for scientific visualization), so it will be possible to employ a wide range of visualization techniques in many application fields, and moreover, it is possible to interactively manipulate data-sets in order to achieve a more effective way of visualization. © 2006 The Visualization Society of Japan and Ohmsha, Ltd.

Keywords: Augmented reality | Interaction techniques | Scientific visualization

Abstract: Incremental forming applications are currently increasing in industry, especially for the production of small batches or single components. In fact, sufficient know-how is now available for the manufacture of simple products. However, further efforts are required to reduce the drawbacks of typical incremental forming processes, which compromise important advantages in terms of costs and flexibility. First of all the duration of the process, usually a few minutes, influences this kind of process, even if the operations are carried out on high-speed digitally controlled units. A tendency to produce inaccurate parts can reduce industrial interest with respect to incremental forming. Different approaches could be proposed to reduce this drawback, and a feasible and easily implemented strategy is the design of modified trajectories able to take into account both springback effects and stiffness reduction owing to specific clamping equipment. In this paper, such a strategy is pursued by integrating an on-line measuring system, composed of a digital inspector and a computer numerically controlled (CNC) open program. The geometry obtained is sampled in particular steps and an appropriate routine modifies the coordinates of the future punch path. This procedure of automatic control has been developed using an effective finite element (FE) code. An experimental design illustrates the potential use of the suggested methodology. © IMechE 2005.

Keywords: Incremental forming | Net shape | Sheet metal forming

Abstract: Incremental Forming processes have been introduced in the recent past as an alternative to the money consuming stamping technology, when small batches have to be manufactured. Anyway, they introduce some advantages in terms of flexibility and material formability but, also, some problems such as the dimensional accuracy decreasing. In this paper, a particular application is carried out taking into account the development of an innovative technique to produce a customised ankle support. In this way Incremental Forming process has been selected for the sheet profiling, exalting the role that this technology may play when single complex product has to be manufactured. The producing procedure finishes with a measure of the dimensional accuracy that shown a good result for the desired application. © 2005 Elsevier B.V. All rights reserved.

Keywords: Ankle support | Incremental Forming | Reverse engineering

Abstract: As known, incremental forming is a flexible and innovative sheet metal forming process which allows complex shape shells forming without the need for any die. For these reasons, incremental forming is nowadays suggested for rapid prototyping and customised products. The present paper is focused on material formability in incremental forming and, in particular, on the evaluation and compensation of elastic springback. The latter significantly modifies the imposed shape. For this purpose, a deeper assessment of the process was developed following three different approaches. First of all, a wide experimental investigation on the influence of some relevant process parameters was developed. At the same time, an explicit FEM analysis of incremental forming process was carried out in order to verify its effectiveness and, as a consequence, its ability to be used as a design tool. Furthermore, the obtained parts were analysed by a reverse engineering technique and the measured geometry was numerically compared with the desired one, with the aim to quantify the geometrical discrepancies. In this way, an integrated numerical/experimental procedure is proposed in order to limit the shape defects between the obtained geometry and the desired one. © 2004 Elsevier B.V. All rights reserved.

Keywords: FEM | Geometrical accuracy | Incremental forming

Abstract: Incremental forming is nowadays increasing its presence in industry as a new but interesting process, especially for production of small batches or unique components. Anyway, relevant efforts have to be spent in order to reduce the typical incremental forming processes drawbacks that risk to belittle the high advantages in terms of costs and simplicity. In fact, the process duration, usually equal to several minutes even if the operations are carried out on high speed numerical controlled units, and a certain tendency to produce no precise parts, can reduce industrial interest about incremental forming. A possible strategy to reduce the latter item is the design of modified trajectories able to take into account both the springback effects and the stiffness reduction due to the particular clamping equipment. In this paper the above introduced strategy is pursued integrating an on-line measuring system, based on a digital inspector, and a CNC open program. The actual geometry is acquired in some remarkable points and a compensation routine modifies the coordinates of the future punch path. The modification policy has been developed by using an effective FE code. An experimental verification shows the good potentiality of the suggested methodology.