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A thermoplastic matrix composite flat panel stiffened by induction welded stringers, according to a typical aerospace configuration was tested. A Poly-Ether-Ether-Ketone (PEEK) matrix reinforced by carbon fibers was adopted. The aim of this study was to investigate the shear buckling, a load condition that is very common for the aerospace structures, of the panel obtained using a non-conventional approach for its fabrication, that is, induction welding. A finite element (FE) model capable to describe the buckling and the postbuckling behavior of the stiffened panel was also developed and compared with experimental results. Testing was performed using fixtures suitably designed to transmit a pure shear to the panel, and strain gauges were mounted on the external surfaces to measure the deformations.

Incremental sheet forming represents a relatively new process appointed to form sheets of pure metals, alloys, polymers, and composites for the manufacture of components in fields where customized production in a short time and at a low cost is required. Its most common variant, named single-point incremental forming, is a flexible process using very simple tooling; the sheet is clamped along the edges and a hemispherical-headed tool follows a required path, to deform the sheet locally. In so doing, better formability is reached without any dedicated dies and for low-forming forces, which represent some of the attractive features of this process. Nevertheless, and with special reference to thermoplastic sheets, incremental formed parts suffer from peculiar defects like twisting and wrinkling. In this numerical work, analyses were conducted through a commercial finite element code by varying the toolpath strategy of the incremental forming of polycarbonate sheets. The investigation of some features like the forming forces, the deformation states, the energy levels, and the forming time was carried out, to determine the toolpath strategy able to optimize the incremental forming process of polymer sheets. The results of the numerical analyses highlight a reduction of the forming forces when using toolpaths alternating diagonal up and vertical down steps and, presumably, a reduced risk of failures and defects. Furthermore, these toolpath strategies solutions also have a positive impact on the environment in terms of energy and do not significantly increase the manufacturing time.

Background The assessment of the force exerted during a gesture in human motion analysis can provide direct and indirect information regarding the expended energy, especially during the execution of a sport gesture. In this field, assessment and improvement of the performance can be supported by instrumented devices able to measure and process mechanical quantities. In cycling, strain gauges-based instrumented pedals represent one of the last innovations in the sector, because they can provide data about the power exerted (produced) during training and the pedal efficiency. Optimization of the strain-gauges positioning is thus required to improve accuracy in the exerted force estimation. Methods A new technique to give a support for evaluating the best compromise between maximum sensitivity and ease of assembly was developed in the present work, based on a Finite Element Model (FEM) and a parametric analysis of the strain field at different sensor placements. Optimal positions were identified as those combining high sensitivity and low dependence from positioning inaccuracies. Results Parametric strain-load trends obtained from the developed model show a linear behavior of strain gauges pairs and confirm that there is a good sensitivity of the adopted sensors if they are mounted in handy positions of the developed load cell. Discussion The conducted analysis enables to calculate the sensitivity of the load cell to the exerted forces, and evaluates its dependence to the positioning of strain gauges, and makes it possible to appropriately choose strain gauges positioning in areas where border effects are minimized. The strain distributions obtained by the FEM analysis in the presented load cells gives useful indications for all the situations where small strain gauges are requested to be mounted on a reduced offered area.

Concerning strengthening techniques for existing masonry walls, the trend is toward the use of Fibre Reinforced Mortar (FRM) with both a significant increase of the mortar strength, and a drastic thickness reduction of the added external layers. In the present analysis, the focus is posed on some new lime mortar types which possess a very high strength in tension, although the elastic modulus remains in a normal range, leading so to a considerable toughness increase. The G-FRM system is composed with a glass fibre mesh which must possess a tensile resistance larger than the one of the mortar area including it, and this allows introducing some ductility in the composite. A total of 14 diagonal compression tests of masonry walls reinforced with G-FRM have been completed at LISG (Structural Engineering and Geotechnics Laboratory, University of Bologna), encompassing different FRM combinations. More precisely, the walls were reinforced with three different lime mortar compounds with layer thicknesses of 12, 15 and 30 mm, and reinforced with two different glass fibre meshes and two different arrangements of steel micro-wire strips. The performed tests showed that the interpretation of the observed behaviour needs a sound theoretical basis of the experimental setup, avoiding the simple analysis reported in standards and codes. A finite element model of the experimental setup was prepared, able to identify the features of the observed behaviour. Following this suggestion, a new theoretical model based on Mohr-Coulomb plasticity was defined and applied to the interpretation of a large database of experimental tests with a very good agreement.

In the field of impact response of thermoplastic reinforced composites, several investigations about material behaviour in terms of delamination, indentation and fracture mechanism were conducted. Although a significant influence of the polymer temperature on the overall material impact response is expected, a limited number of studies are available in this regard. Most of the available scientific evidence concerns thermosetting composites and thermoplastic composites response only at room temperature. In particular, the purpose of this contribution is to better understand the dissipation mechanisms involved in thermoplastic reinforced composite under impact conditions for different temperatures. Starting from the few available literature data about the modelling of the problem, the aim of the present work is the development of a numerical approach able to reproduce the experimentally tested conditions. An experimental campaign on hot pressed polyamide 6 /basalt plain fabric laminates impact was selected as the benchmark for the numerical approach. The laminates impact response at increasing values of impact energy between 5J and 30J were simulated under three temperature conditions set around the polymer transition temperature (40°C, 80°C and 100°C). By validating the overall numerical model response on the room temperature experiment, considerations about the magnitude of viscous dissipation and its influence, for the different tested temperatures and in function of the adopted lamination technology, were made.

Within the framework of EUROfusion R&D activity, a research campaign has been carried out at the University of Palermo, in close cooperation with ENEA labs, in order to assess the thermo-mechanical performances of the DEMO Water-Cooled Lithium Lead (WCLL) inboard blanket equatorial module, whether properly integrated within its whole inboard segment. In particular, a detailed 3D model of this segment, including all the other modules, the back-supporting structure and the attachment system, has been considered in order to realistically simulate the boundary conditions affecting the equatorial module behaviour. The study has been focused on the investigation of the module thermo-mechanical performances under the Over Pressurization (Level D) loading scenario envisaged for the DEMO WCLL breeding blanket as a consequence of a small in-box Loss Of Coolant Accident (LOCA) accident. A theoretical-numerical approach, based on the Finite Element Method (FEM), has been followed and the qualified ABAQUS v. 6.14 commercial FEM code has been adopted. The obtained thermo-mechanical results have been assessed in order to verify their compliance with the design criteria foreseen for the structural material. To this purpose, a stress linearization procedure has been performed along the most critical paths located within the inboard equatorial module structure, in order to check the fulfilment of Level D rules prescribed by the SDC-IC structural design code. The obtained results are herewith presented and critically discussed.

In the context of the European fusion roadmap, the divertor tokamak test (DTT) experimental reactor is intended to investigate alternative divertor configurations in view of the EU-DEMO power exhaust handling necessities. The six poloidal field coils of this tokamak are responsible for the plasma shape and equilibrium, and numerous steps were taken to obtain a design that is magnetically consistent with plasma requirements and structurally compliant with the chosen failure criterion. This work presents the structural assessment that has been performed on the poloidal coil system, taking into account the cooldown process, the energisation to operating conditions and fatigue. Finite Element Analysis has been employed as the principal means of investigation.

Although the high performance thermoplastics matrix composites have been studied for more than thirty years, only recently their advantages have been properly perceived and exploited, for a wide range of applications either in secondary either in primary aeronautical structures. In this work, compression testing of a flat panel stiffened with L-shaped stringers made of Polyphenylene-sulfide (PPS) matrix reinforced with carbon fibres, is presented. The stiffeners were joined to the base plate by induction welding, as reported in a former study. The numerical activities, aimed at static, buckling and post-buckling analysis, first of a single stringer, then of the stiffened panel under compressive load, provided results in good agreement with the experimental ones. The analyses were performed taking into account either for the geometric non-linearity associated with the large deformations of the structures under the action of compressive loads either for the local buckling of the flanges composing the stringers. Experimental activities were aimed at the characterization of the adopted materials with a special focus on the determination of buckling loads either of an L-shaped stringer either of a panel stiffened with four stingers. In both cases an excellent structural behaviour was shown, the panel and a single stringer being able to take huge loads after the first buckling appeared. The panel, in particular, showed an excellent post-buckling strength and broke by buckling failure of stringers. The welded interfaces did not fail indicating that thermoplastic welding is a suitable technique for assembly composite structural elements.

The aim of this paper is to model and to compare the results of the mechanical characterization, carried out on numerical models and real specimens, of uniform P-scaffolds with different porosity values. The analysis includes the morphological characterization of 3D printed specimens and the implementation of a FEM shell model to reproduce a compressive test suitable for mechanical properties evaluation of PLA scaffolds. Young modulus and yield strength were also obtained, in order to verify the numerical model accuracy, by experimental tests on 3D printed PLA scaffolds. Numerical results showed that the shell model was able to reproduce, more efficiently compared to a solid model proposed in a previous work, both elastic and plastic behavior of the scaffolds, providing elastic modulus values very close to the experimental ones. On the other hand, the not very high quality of the 3D printing, detected by MicroCT analysis, caused a significant dispersion in the yield strength numerical values respect to the real data. Anyway, an inverse correlation between mechanical properties and porosity was found as expected. The elastic modulus values were similar to the typical values of the trabecular bone for whose regeneration this kind of scaffolds is usually employed.

Bird impacts can be extremely critical events for the air transport safety. Since aircraft structures have become more and more complex components, the numerical prediction of the damage onset and evolution induced by a bird impact has become a very challenging task. The aim of this work is to provide a brief overview of the numerical techniques adopted for the prediction of the bird impact phenomenon on a leading edge of a regional aircraft wing. Smooth Particle Hydrodynamics (SPH), Rigid and Lagrangian models have been investigated and the results have been compared and critically assessed.

In order to prevent in-flight fatigue failure, a numerical analysis of in service-operative cases is an useful approach for preliminary evaluation of most stressed and critical zones in components of aeronautical engine. The zero-stage compressor rotor disk and blades represent one of the most critical part of aircraft turbojet. This paper presents a verification FEM analysis of this component. An accurate 3D scanning was performed to reconstruct both blade and disk real geometry and the detailed point cloud was obtained and opportunely elaborated by using specific software to generate CAD sections and volumes given in input to finite element analysis. The stress field due to different operating conditions is studied for a suitable evaluation of the most stressed and critical areas where a failure may occur, particularly near the rotor connection under contact conditions. FEM and flight data analysis are finally used for a subsequent fatigue life verification, based on classical Palmgren Miner’ rule. The suggested procedure for verification of engine aeronautical component is here optimized for maintenance program improvements.

A mold insert is an important component of the molds commonly used in die casting processes. Its purpose is to realize particular shapes in castings, like cavities and undercuts. It is also used for improving the cooling system in some critical areas. Each insert has at least one simple cooling channel for controlling the thermal state of the mold and for cooling every hot spot efficiently. The severe cyclical thermal conditions, together with the mechanical stresses due at first to the molten metal cast in the shape and then due to the solidified casting, submit the insert to thermomechanical fatigue. The thermomechanical fatigue is the main cause of the cracks observed on insert surfaces after a certain number of cycles, which makes the component unusable and requests its substitution. This circumstance has a negative influence on direct and indirect costs. In this case, the phenomenon has been studied on a mold insert used for realizing an oil drain channel in an aluminum alloy cylinder block made through die casting process. The aim of the present work is to determinate the zones which are mostly subjected to high temperature and high thermal gradients and to design and analyze a more efficient cooling system by using conformal channels on the same insert realized in additive manufacturing.

This paper presents a comparison between the performances of electrical machines equipped with slightly asymmetrical windings. More in detail, by modifying the stator geometry of an Interior Permanent Magnet Synchronous Machine equipped with a symmetrical winding configuration, other two slightly asymmetrical winding topologies are obtained. The three models are, then, analyzed by means of a finite element method (FEM) and the related results are compared in terms of cogging torque, static characteristics and leakage factor. The obtained results demonstrate that the adoption of slightly asymmetrical windings could be an interesting alternative solution during the design stage of electrical machines.

AISC358–16 provides seismic pre-qualification rules and design procedures for fully restrained extended stiffened end-plate bolted connections, while the cases of partially restrained connections are generally not considered for seismic applications. However, provided that the failure of both bolts and the welds is prevented, partially restrained joints may exhibit satisfactory ductile behavior, also accommodating interstory drift rotation larger than 0.04 rad. This performance can be achieved if the resistance of brittle zones of the connections is greater than the ultimate resistance of the ductile components, as experimentally proved in some recent European research projects. Therefore, the study presented in this article aims at proposing design rules for partially restrained connections in order to meet the prequalification limits given by AISC358–16. To achieve this purpose, a comprehensive parametric study based on finite element analysis (FEAs) was carried out. The numerical results show that the proposed AISC-compliant procedure can guarantee satisfactory performance of partially restrained connections, which exhibit good ductility and dissipation capacity.

Within the framework of the pre-conceptual design of the EU-DEMO Breeding Blanket (BB) supported by EUROfusion action, results of the research activities carried out in the last years have highlighted that changes in the proposed Water Cooled Lithium Lead (WCLL) BB design have to be considered, especially as to the liquid breeder circulation path within the BB module. Therefore, in view of the definition of a final WCLL BB module layout, a parametric campaign of numerical analyses has been carried out at the University of Palermo in order to assess the impact of different SPs configurations on the module thermo-mechanical performances. To this purpose, attention has been focussed on the WCLL BB Outboard Central Segment and two different concepts have been considered, both based on the use of mixed horizontal (toroidal-radial) and vertical (poloidal-radial) SPs and mainly differing as to the allowed breeder flow path. For each concept, three toroidal-radial cells of the outboard module equatorial region have been considered and the effects of the thickness, pitch and radial length of their SPs on the module thermo-mechanical performances have been investigated under the Over-Pressurization accidental scenario, following an in-box Loss Of Coolant Accident. The study has been carried out following a theoretical-numerical approach based on the Finite Element Method (FEM) and adopting the quoted Abaqus FEM code. The results obtained are herewith reported and critically discussed.

Within the framework of EUROfusion R&D activities a research campaign has been performed at CEA-Saclay, in close collaboration with the University of Palermo, in order to investigate thermal and thermomechanical performances of the “Optimized Conservative” concept of DEMO Helium-Cooled Lithium Lead breeding blanket (HCLL). Attention has been paid to the HCLL outboard equatorial module (OEM) when subjected to the steady state nominal loading scenario. To this purpose three simplified 3D models, characterized by an increasing level of detail, have been set-up taking into account, firstly, a single radial-toroidal slice, then a basic module geometric unity composed by two adjacent slices and adding, lastly, the peripheral poloidal region. This latter 3D model has allowed the assessment of the Caps potential influence on the module thermal and thermomechanical behaviour. For each investigated 3D model, thermal and thermomechanical analyses have been performed and a stress linearization procedure has been carried out in order to verify the fulfilment of the criteria prescribed by the RCC-MRx 2015 code. The study has been performed adopting a numerical approach, based on the Finite Element Method (FEM), and adopting the Siemens NX v. 10.0 software in order to discretize the geometric domain, whereas thermal and thermomechanical calculations have been carried out using the Cast3 M 2015 FEM code. The obtained results, herewith reported and critically discussed, allow predicting a good thermal and mechanical behaviour of the “Optimized Conservative” concept of DEMO HCLL OEM, even if some small modifications to the module cooling scheme should be performed in order to avoid the insurgence of hotspots where temperature is slightly above the Eurofer limit temperature (550 °C). This will entail, from the mechanical point of view, a reduction of the secondary stress amount which is the main responsible of the failure in RCC-MRx criteria verification within First Wall-Side Wall bend region.

The development of techniques able to check the structural health of a wind blade is very important. An innovative and promising technique applicable at this aim is the SMArt thermography. It exploits the electro-thermal properties of SMArt composites, in order to detect the structural flaws using an embedded source. Such a system enables a built-in, fast, cost-effective and in-depth assessment of the structural damage as it overcomes the limitations of standard thermography. With the aim for developing a reliable diagnostic method based on SMArt thermography, a preliminary numerical model was implemented in order to simulate the heating and the subsequent cooling of a GFRP composite laminate with embedded SMA wires. The heat source was represented by the Joule effect originated in the SMA wires and supplied as power density. The analysis of the resulting thermal maps at different values of power density provided the optimal levels of current amplitude and period to be applied in the subsequent experimental applications.

The paper addresses the complexities for a reliable numerical simulation of the roll forming process. During the process, the material is progressively bent accumulating plastic deformation at each forming step. Strain hardening limits the material formability and may causes flaws of the final shape. A simplified method for the FEM modeling of the process has been developed introducing a narrow-strip 3D model. This approach leads better performance than the classical modeling method, in terms of results reliability and low computational time. In order to verify the proposed model, an experimental campaign of testing, for a specific roll forming production process, was carried out. On the quasi-static regime, the post necking behavior of the sheet metal was characterized. The Vickers hardness and the plastic strain of uniaxial tests were empirically correlated. By the hardness correlation, the plastic strain accumulated at different stages of the process was evaluated and compared with the numerical results. Further possible improvements of the method are highlighted.

In cycling the use of instrumented devices to measure mechanical quantities can give a great support to the assessment and the improvement of the performance. Among different devices and technologies adopted, instrumented pedals based on strain gauges represent one of the last innovations in the sector, used to determine both the level of power in training and the pedal efficiency. The accuracy of these instruments is strictly dependent on the strain gauges positioning on custom load cells. In the present work a new technique, based on a simulation of the strain field at different sensor placements, was developed, to give a support for evaluating the best compromise between maximum sensitivity and ease of assembly. The proposed method can be easily applied to a wide range of force sensors, especially the ones where the available area to fix sensors is reduced and strain gauges adopted are very small, thus guaranteeing a reduction of mounting errors and increasing the quality of the final product.

Historically, asymmetrical windings in electrical machines have been rarely used and only for specified needs, because the adoption of symmetrical configurations has always been considered the only solution during the design stage of electrical machines. The aim of this work is to demonstrate with several examples that the use of slightly asymmetrical windings can be a reasonable choice and, in certain cases, a favorable option during the machine design stage, allowing the possibility of selecting a wider range of slot/pole number combinations, without affecting the performances of the machines. More in detail, an interior permanent magnet synchronous machine equipped with a symmetrical 3-phase winding has been considered as a reference structure. Then, this geometry has been adequately modified in other 3 models to equip asymmetrical windings on each of the modified structures. Afterwards, the performances have been compared in generated torque, magnetic forces, magnetomotive force harmonic content, cogging torque, and iron core losses. This comparison has led to promising results, obtaining in some cases even a reduction of power losses, cogging torque, and harmonic content.

This work concerns the realization of dies to produce helical gears by metal powder compaction. Due to the helicoidal geometry of the cylindrical gears, the punch, in addition to the axial motion, must necessarily rotate to "cross" the die. The innovative idea is to design a perfectly functioning system that can generate any helix angle (β) in the range of interest 0°-30°, using the simple contact between punch and die cavity during the rotation. First of all, the punch-die system was treated as a self-locking screw to determine the maximum s-value at which punch could be clamped inside the die during pressing. The analysis encouraged the execution of experimental tests related to a die with β = 5°, obtaining excellent results. Subsequently, FEM (Finite Element Method) analyses were performed on the static behavior of the die, subjected to the pressures exerted by powder and shrink-fitting ring, for three different β-values: 5°, 18° and 30°. The results obtained for the latter two angles were compared with those related to the die with β equal to 5°, considered valid thanks to experimentation, in order to theoretically verify the correct functioning even of dies with larger angles.

This paper deals with pre-concept studies of DEMO divertor cassette-to-vacuum vessel locking system under the work program WP13-DAS-07-T06: Divertor Remote Maintenance System pre-concept study. An iterative design process, consistent with Systems Engineering guidelines and named Iterative and Participative Axiomatic Design Process (IPADeP), is used in this paper to propose new innovative solutions for divertor locking system, which can overcome the difficulties in applying the ITER principles to DEMO. The solutions conceived have been analysed from the structural point of view using the software Ansys and, eventually, evaluated using the methodology known as Fuzzy-Analytic Hierarchy Process. Due to the lack and the uncertainty of the requirements in this early conceptual design stage, the aim is to cover a first iteration of an iterative and incremental process to propose an innovative design concept to be developed in more details as the information will be completed.

U cilju poboljšanja najviših performansi, materijali u strojarskim konstrukcijama su često vođeni ka sve bližim i bližim kritičnim granicama. Razmotrimo, na primjer, kako progresivno smanjenje debljine može dovesti do nepredviđenih efekata u stabilnosti lima, sve do brzog loma cjelokupne konstrukcije. Ovaj rizik je posebice poznat konstruktorima teleskopskih dizalica, koje se koriste za pokretanje radnih platformi. U ovom radu, numeričkim pristupom i ANSYS kodom, čvrstoća i stabilnost teleskopske dizalice su verificirani. Nakon preliminarne teorijske analize, različite konfiguracije opterećenja i graničnih uvjeta su razmatrane u skladu s uvjetima realne uporabe. Kao opći rezultat, potvrđeno je da su naprezanja bila u okviru elastičnih granica materijala, osim u ograničenom broju kontaktnih površina, gdje su korišteni posebni kontaktni elementi za sprječavanje loma. Osim toga, linearne tehnike izvijanja su pokazale da su kritična opterećenja i odgovarajući moduli izvijanja bili veći od najtežih uvjeta rada; stabilnost je potvrđena. Konačno, FEM simulacije dopuštaju smanjenje brojnih eksperimenata, nudeći time brze metode za poboljšanje konstrukcija., With the aim at improving the highest performances, materials in mechanical structures are constantly pushed closer and closer to their critical limits. Consider, for example, how the progressive reduction in thickness may lead to unforeseen effects in the instability of metal sheets, until the rapid collapse of the whole structure. This risk is specially known by designers of telescopic booms, used for moving aerial platforms. In this paper, by a numerical approach and ANSYS code, structural resistance and stability of a telescopic boom were verified. After a preliminary theoretical analysis, different loads and boundary configurations were considered in accordance with the most common conditions of real utilisation. As general result, it was confirmed that stresses were under the elastic limit of materials, except in a very limited number of contact zones, where specific connecting solutions have to be installed to prevent failures. Furthermore, linear buckling techniques showed that critical loads and corresponding buckling modes were higher than the most extreme working conditions; thus, structural stability was also confirmed. Finally, the large adoption of FEM simulations permitted to reduce the experiments, offering a fast methodology for improvements in design.

This paper presents a comparison of the performances between IPMSMs (Interior Permanent Magnet Synchronous Machine) with a symmetrical and with two different types of unsymmetrical windings. The aim is to demonstrate that the adoption of slightly unsymmetrical windings does not significantly affect the performances of the machines, both in terms of cogging torque and torque/load angle characteristics, providing also the advantage of a higher possibility of choice in terms of slot number/poles ratio. More in particular, an IPMSM model (named IPMSM-1) derived from a commercial geometry equipped with a symmetrical winding is analyzed by using a Finite Element Method (FEM) approach. The simulation results regarding the cogging torque trend, the static characteristics and the related harmonic analysis are shown and discussed. Afterwards, two other IPMSM models with unsymmetrical windings are obtained by modifying the IPMSM-1 stator structure, but maintaining the same rotor configuration. FEM analysis are carried out also for these geometries and the related simulation results are compared with those obtained for the IPMSM-1 model. From this comparison it can be stated that the equipment of slightly unsymmetrical windings can be a viable choice during the design process of rotating electrical machines.

This paper presents the comparison between the cogging torques produced by four IPMSGs (Interior Permanent Magnet Synchronous Generators) with different stator winding configurations. More in detail, an IPMSG model, which is derived from a commercial geometry, is analyzed through means of a FEM (Finite Element Method) approach. Then, three more structures are determined and analyzed by adequately changing the number of stator slots of the basic IPMSG stator structure and by maintaining the same rotor configuration. From the obtained simulation results, the cogging torque components for each structure are determined and compared. From this comparison, it can be stated that the use of dissymmetric windings does not affect significantly the generated cogging torque.

This paper presents a possible minimization procedure of the cogging torque generated by an IPMSM (Interior Permanent Magnet Synchronous Machine) with a progressive modification of a basic geometrical structure of rotor laminates. More in detail, an IPMSM model is analyzed by using a Finite Element Method (FEM) approach. Then, other IPMSM models, which are obtained by modifying the geometry of the IPMSM rotor laminates and by maintaining the same stator configuration, are proposed and discussed. From the obtained simulation results, the cogging torque components for each structure are determined by means of FEM and compared to each other. From this comparison, it can be stated that the cogging torque is significantly related to the laminate geometry and it is demonstrated that the cogging torque components can be theoretically canceled by choosing a specified structure of the laminates.

Steel plate shear walls (SPSWs) are innovative systems able to confer to either new or existing structures a significant capacity to resist earthquake and wind loads. Many tests have shown that these devices may exhibit high strength, initial stiffness and ductility, as well as an excellent ability to dissipate energy. When full SPSWs are used as bracing devices of buildings, they may induce excessive stresses in the surrounding main structure where they are inserted, so to require the adoption of large cross section profiles. For this reason, perforated steel panels, which are weakened by holes aiming at limiting the actions transmitted to the surrounding frame members, represent a valid alternative to full panels. In this work, aiming at showing the advantages of such devices, a FEM model of perforated panels has been calibrated on the basis of recent experimental tests. Subsequently, a parametric FEM analysis on different series of perforated panels, by changing the number and diameter of the holes, the plate thickness and the metal material, has been carried out. Finally, the achieved numerical results have been used to set up design charts to correctly estimate the strength and stiffness of perforated metal shear panels.

Sequence design for shape-rolling processes consists of roll pass and profile design, i.e., transforming the billet into a final shape. For the prediction of the mean effective strain of the workpiece during rod rolling, an analytical model by Shinokura and Takai was used. They verified the formula by applying it to a variety of rod-rolling geometries (oval-square, oval-round, square diamond, and diamond-diamond). Today, on the other hand, the finite element (FE) techniques allow analysis of rolling processes in such a way as to simplify the work of design engineers. In this study, a round-oval pass and a round-flat oval pass are analyzed for steel rod rolling. In particular, the analysis of the spread, the surface profile, and cross-sectional area of the workpiece were conducted during rolling. Experimental data such as the maximum spread and the radius are compared with the results of the analytical model and FE analysis.

The use of hard metals, in particular for cutting tools, is becoming wider. Their manufacturing cost, higher than traditional steel, is compensated by an increased lifetime. This work involves the rheological characterization of a WC–Co compound, in order to evaluate its viscosity for different values of strain rate. Following this characterization, the data are implemented in a FEM code, in order to simulate the extrusion processes of such compounds to manufacture hard metal bars. This study highlights the importance of an accurate viscosity evaluation of these mixtures and the correct setting of FEM parameters in order to predict successfully extrusion processes. As an example, an analysis is presented for the case of cutting tools with helical holes for the passing of fluid coolant.

Main target of this paper is to analyse the advantages in the use of the Direct Modeling in the Virtual Prototyping processes and in the multiphysics analyses with the help of Reverse Engineering procedures. It is a recent CAD technique that allows the creation and/or modification of models that don’t need parameters and constraints, as on the contrary happens in the Feature Based Modeling. So, it is possible to change the shapes and the dimensions of the original prototypes very easily. Hence, in this paper a methodology devised to acquire and modify a “reconstructed” (non-parametric) model to improve and then to submit it to FEM analysis is presented. Furthermore, it is realized and doesn’t even need the Feature Recognition phase of a typical Reverse Engineering process. In particular, this methodology was applied to a frame of a bicycle used as case study. Its shape was acquired by means of a laser scanner and its virtual prototype was “reconstructed”. In addition, starting from it, two alternative frames were obtained and then easily modified by means of the Direct Modeling techniques. Then, they were submitted to FEM analyses to get different solutions with less weight but similar mechanical performances. Afterwards, the ergonomics of the modified configurations was tested by means of different percentile virtual manikins to plan the physical prototyping of a new improved bicycle.

This paper presents the analysis, characterization and comparison of the cogging torque components generated by five different IPMSM rotor structures. More in detail, an IPMSM model (named IPMSM1), which is derived from a commercial geometry, is analyzed by using a Finite Element Method (FEM) approach. Then, four other IPMSM models, which are obtained by modifying the IPMSM1 rotor structure and by maintaining the same stator configuration, are proposed and analyzed. From the obtained simulation results, the cogging torque components for each structure are determined and compared. From this comparison, a significant cogging torque decrease is occurring for the modified geometries, without affecting the values of the generated torque. Furthermore, a meaningful relationship between the peak values of the cogging torque and the gradients of the flux density around the neutral area is reported and discussed. Therefore, simple structure modifications applied to the rotor geometry can bring significant improvements in terms of motor performances and cogging torque reduction.

In this paper, a torque/weight and torque/moment of inertia ratio optimization procedure for interior permanent magnet syncronous motors (IPMSMs) is presented. More in detail, a performance comparison between several IPMSM rotor structures has been carried out in order to determine the optimum geometry that can maximize the torque/weight and torque/moment of inertia ratios. A commercial motor, with known electrical and mechanical characteristics, has been taken as reference. Its rotor structure has been modified several times, obtaining different rotor geometries and, therefore, many IPMSM models with different electrical and mechanical characteristics. The finite element method (FEM) analysis of each IPMSMs has been performed using the software FEMM, allowing to determine the related torque/load-angle characteristics. From the comparison between the torque/load-angle characteristics of the different IPMSM structures, it can be stated that significant performance improvements can be obtained in dependence not only of the type of permanent magnets and their direction of magnetization, but also of the PM displacement within the rotor.

In this paper the mechanical behavior of a Tire Derived Material is presented in details. Tensile, compression, simple shear and volumetric test are performed. Tests showed low tensile strength, stiffening behavior under compression, hysteresis and strain rate sensitivity of the material. Four hyperelastic models were fitted to the collected experimental data to investigate the rate-independent behavior of the material when used as anti-vibration mat for railway track applications. Finally finite element simulations of tests on the railway track mat have been carried out. The comparison of experimental and numerical results shows a good agreement in a certain range of deformation. © 2014 Elsevier Ltd. All rights reserved.

This paper presents the experimental behaviour of two reinforced concrete T-beams strengthened in shear with CFRP. The beams are extracted from an important building of the mid-'30s in Rome. The goal of this research is to evaluate the shear strength of the retrofitted beams with the simultaneous occurrence of a negative bending moment. The tests are performed at the Experimental Laboratory of the Structural Department of the University “Roma Tre”. In the meantime the two beams are modelled with the software ATENA in order to perform numerical simulations of the tests. The numerical results seem to be in good agreement with the experimental data in terms of load– displacement response, strain state, crack pattern and failure mode.

Bonded joints are highly sensitive to the presence of defects and to the degradation phenomena, and this aspect represents the primary obstacle to their use in different structural engineering applications. Delamination in a bonded joint represents, in fact, one of the primary, most common and insidious causes of damage. In this paper, a numerical–experimental study on the crack propagation along the adhesive layer of a bonded joint specimen is carried out. Experimental study is focused on the evaluation of the damage modalities of a bonded joint when the specimens are subject to fatigue load. Experimental tests are compared with the results of several numerical analysis performed in ANSYS environment. A crack growth model is implemented in the finite element method solver and allows the simulation of the progressive delamination process. Comparison between numerical results and experimental tests allows to identify the descriptive numerical parameters of fatigue crack propagation, which may be used in the structures design.

In some powder metallurgy part forming, when high compacting loads would require a too large single shrink fitted die, or the inner die diameter is very large but the compaction area is modest, twice shrink fitted dies, which are relatively expensive and complex to build, should be used. In both cases, at any given compacting load, the design should minimise dimensions and stresses. The design targets are minimum die size, optimum intermediate diameter and optimum interference, with maximum stresses on each die item lower than those allowable for the selected materials. In dual mode, for fixed overall dimension, intermediate diameters and shrink fitting interference should enable to maximise the compacting load without exceeding the allowable maximum stresses. In the first part of this work, for cylindrical shapes (circular profile dies) and axisymmetric plane stress problems, dimensions, interferences and stress–strain states have been analytically calculated to optimise doubly shrink fitted dies in the abovementioned sense. In the second part, the same evaluations for axisymmetric generic problems have been carried out by finite element method (FEM) approach integrated in an optimisation procedure. The minimum overall dimensions of the die are presented as a function of the ratio between applied load and maximum allowable stress. Corresponding interferences and optimum diameters have been calculated. Some approximate equations for a quick and handy optimisation are presented. The differences between analytical and numerical results obviously depend on the consideration of the actually stressed length, or compact height, and total die height. The comparison indicates that FEM analyses are needed since analytical calculations generally give low approximations, especially for some die geometries.

The complete load-vs-displacement curves obtained by four-point-bending tests on Steel Fiber Reinforced Concrete (SFRC) beams are predicted by using a nonlinear finite element code based on the Modified Compression Field Theory (MCFT) and the Disturbed Stress Field Model (DSFM) suitably adapted for SFRC elements. The effect of fibers on the shear-flexure response is taken into account, mainly incorporating tensile stress-strain analytical relationship for SFRC. The numerical results show the effectiveness of the model for prediction of the behavior of the tested specimens reinforced with light amount of stirrups or with fibers only. © 2008 American Institute of Physics.

Although the correct determination of the material constitutive properties is the key to the successful FEM simulation of machining, the material rheological behaviour at the high temperature, strain rate, and strain conditions encountered in chip formation cannot be provided by normal stress-strain curves or impact tests. In this paper, a neural network approach is used to model the flow dynamics work material behaviour by reconstructing the stress-strain curves of carbon steel work material from tensile test experimental data.

In the design of roll stands for use in grooved steel rod rolling, the contact pressure between the rolls and the incoming workpiece is very important. This value can be estimated with the help of a number of analytical and seiniempirical models described in the published scientific and technical literature. In this study, the possibility of using numerical simulation in determining the contact pressure during the rolling of a round bar with oval grooves is analyzed. The results of the numerical analyses are then compared with those of two other modified analytical models.

In shape rolling process, the definition of roll pass and profile design is important. For the prediction of workpiece sectional shape, for some rod rolling passes, an analytical model by Shinokura and Takai was proposed and verified. The application of FE techniques to the rod rolling process lets to study some other passes with much simplicity. In this paper, for round-flat oval pass and round-flat pass, in rebar rolling, the experimental values of maximum spread and of radius of the rebar have been carried out and compared with the results of the analytical model and of the FEM analysis. The FE model has been developed with MSC.Marc Autoforge program, a FE non-linear solver, dedicated to simulate plastic strain working.

An efficient quality control of produced materials is one of the topical aspects in industry, strongly contributing to the repeatability in the final part properties. Unfortunately, the importance of this task is often underestimated, and stringent procedures during the material production stage are seldom adopted, especially when small and medium enterprises are concerned. Filament winding is a high speed lay down of continuos prescribed patterns used for the composite materials pipes production where a continuous resin-impregnated rowing or tows are wound over a rotating male mandrel. In this process, vantage as optimised mechanical property, large structure production, low cost are contemporarily achieving. However the final results can not be independent from control process considerations, so we have focused attention on two main problems: thermosetting polymers cure conditions and thermoplastic polymers softening conditions varying the thermal source and the winding speed. These aspects influence directly the mechanical properties, the fatigue resistance, the produced residual stress and the related deformation, and, from another point of view the process control. In this work, the heating of the composite with an external source, during the fabrication process, is faced to the aim to model the heating flux and thermal gradient in the materials and then the temperature achieved. In a first step, a FEM model was developed to set the film coefficient. In order to calibrate the FEM model, experimental tests were performed on a composite substrate to measure the temperature profile in several positions during the heating process. In a second step, a new FEM model was developed in order to simulate the relative movement between the composite wound on the mandrel and the heating flux and calculate the temperature profile in the composite substrate. The results obtained were related to experimental data obtained in analogous conditions during the filament deposition. In a third step, the last FEM model was modified in order to consider several different types of thermal source and the influence of the thermal source type on filament winding process. The obtained results was related to the experimental data from literature. The analysis results show that finite element method is able to describe with accuracy the heating process during the filament winding process. So, we can define a first procedure to set the most favourable winding speed and thermal source varying the resin and fibre types.

The design of the Demo Oriented NEutron Source (DONES) is the main objective of the Work Package Early Neutron Source (WPENS) of EUROfusion Power Plant Physics and Technology (PPPT) programme. DONES is an IFMIF-based neutron source with the goal of testing and qualifying candidate materials to be used in DEMO and future fusion power plants. In the framework of these activities, a research campaign has been carried out at the University of Palermo, in close cooperation with ENEA labs, in order to assess the thermomechanical performances of the DONES target system, endowed with an integrated Target Assembly (TA) when it undergoes the thermomechanical loads typical of its nominal operating scenario. The effects on TA behaviour of two possible different configurations for the accelerator beam foot-print have been investigated, considering an entire (20 × 5 cm2) or a halved (10 × 5 cm2) beam foot-print area with respect to that of IFMIF. The study has been carried out following a theoretical-numerical approach, based on the Finite Element Method (FEM), and adopting the qualified ABAQUS v. 6.14 commercial FEM code. The obtained thermomechanical results have been assessed in order to check whether the BP deformation field is such to prevent the contact of the BP itself with the High Flux Test Module, as well as to verify their compliance with the design criteria foreseen for the structural material. To this purpose, a stress linearization procedure has been performed along the most critical paths located within the BP, in order to check the fulfilment of the rules prescribed by the ITER structural design code SDC-IC. The obtained results are herewith presented and critically discussed.

This paper presents a finite element analysis on two reinforced concrete beams, extracted from an important building of the '30s in Rome, strengthened in shear with C-FRP and subjected to the simultaneous occurrence of a negative bending moment and shear stresses. The commercial program ATENA was used to perform numerical simulations of the tests. The numerical results seem to be in good agreement with the experimental data in terms of load-displacement response, strain state, crack pattern and failure mode.