Design methods for mobility

The paper presents the development of the scaled prototype of an oscillating-arm Wave Energy Converter (WEC), for onshore installation, suitable to be placed above breakwaters. The mechanical architecture is based on a four-bar linkage moved by a floating buoy with alternate heave motion. The mechanical energy is transferred to the electrical rotary generator with the interposition of a mechanical rectifier, to obtain unidirectional motion at higher speed. Since the power take-off system is fully electromechanical, without pneumatic or hydraulic components, the proposed WEC is characterized by high efficiency and reliability. The functional design of the proposed WEC and its control layout are summarized. Finally, the methodology for designing the 1:15 scale model, destined for the preliminary experimental validation, is discussed, and the embodiment design of the model is outlined.

Keywords: Oscillating arm , Scaled prototype , SDG7 , Wave energy converter

Numerical codes can play an important function in the nautical design when advanced simulation tools are increasingly adopted for prediction purposes, and in particular for the calculation of the interaction between boat parts and surrounding fluids. Fluid-structure interaction analysis (FSI) can help engineers to set the optimum design of a sail and also the influence of panels and battens sail arrangement. The paper describes a methodology that enhances the understanding of panel and battens arrangement, as well as their stiffness on sail performance. Specifically, through the battens position, shape and stiffness parametrization, the sail non-developable shape was optimized, in order to compensate the variation in the angle of attack that occurs following variations in the speed of the wind at different sail heights. For an efficient and robust implementation of integrated Reynolds Averaged Navier Stokes (RANS) equations with Shear Stress Transport (SST) turbulence model and Computational Structural Mechanics (CSM) analysis, the constitutive sailcloth and battens characterization was conducted experimentally. The case study of a mainsail in Dacron© TNF 240 of a Vaurien dinghy boat, offered tangible results to support the methodology by validating it with experimental data.

Keywords: CFD-CSM analysis , Flying shape , Sail battens arrangement , SST model , Triangular membrane modeling , Twisting

In this work, the thermal characterization of a commercially available SiC-based power module named as ACEPACK Drive, specifically designed by STMicroelectronics for automotive applications, was carried out. In particular, we studied the dynamic thermal behaviour and temperature gradient of one leg of the ACEPACK Drive by a combination of high-speed thermal microscopy and conventional thermal mapping. As main result, the temperature distribution on the device turned out to be homogeneous, with a maximum at around ~99 °C in simulated operative condition.

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

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

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

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

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

The present work describes an automotive component design optimization process through a systematic approach. The redesign aims to improve product performance by Powder Bed Fusion metal Additive Manufacturing. The approach allows to match Topology Optimization and Design for Additive Manufacturing by exploiting benefits provided by CAD platforms that integrate CAD, CAE and CAM tools. The Systematic Concept-Selection-Based Approach aims to make redesign simple and effective, allowing design solutions exploration while containing product design lead time. Topology Optimization is the key phase to achieve lightweight design by a double-level optimization approach. In particular, the technique is setup to produce different design variants, whose subsequently undergo a Trade-off study to perform the concept selection step. Finally, one final redesign occurs and a design refinement step is performed to achieve product optimization. The case study is a high performance internal combustion engine piston, which has been redesigned to be produced by Selective Laser Melting process with benefit of weight reduction.

Keywords: Automotive , Design for additive manufacturing , Design method , Re-design , Topology optimization

De-manufacturing is at the basis of the Industry of the Future that competitively and sustainably will manage natural resources. This review retrieved 106 papers investigating the main obstacles that prevent Circular Economy from being a reality and the possible actions to overcome them. The analysis of the literature outlined a great discussion regarding the key topics of CE, de-manufacturing, disassembly and re-manufacturing. The CREDIT analysis proposed by the authors clusters all the risen barriers in 6 factors (Culture, Resources, Economy, Design, Information, Technology) and 18 sub-factors. The CREDIT analysis highlights among the two most critical barriers, the costs of the activities that occur at the EoL stage and the urgency to train designers to approach design thinking to the whole Product Lifecycle; here an innovative focus of research can be more incisive to overcome the actual barriers. Future research needs to focus the attention on the potentialities hidden behind a strong cooperation between academies and enterprises in order to find a balance among the several existing DfX or unveil and tackle their single limitations. Cooperation (industrial symbiosis, academy, etc) and innovative technological solutions of industry 4.0 can help tackle the obstacles.

Keywords: Circular economy , De-manufacturing , Design for de-manufacturing , Design for X , Industry 4.0

Close-range photogrammetry (C-RP) is a widespread and efficient technology to obtain digital models of physical objects. Typical limitations as sharped geometry, shiny surface finishing and light conditions can be overcome by using high-end equipment, which results in increased costs and requires specific skills in human operators. This paper aims to investigate whether a low-cost and simplified approach to C-RP makes it suitable for the 3D acquisition of bodywork components and similar free-form artefacts, as an affordable alternative to 3D scanning in fields where a lower value of accuracy is required. Hence, two commercial C-RP software were used to 3D capture handcrafted car body panels and compare the C-RP models using a 3D scan as a reference within an inspection software. Two case studies are considered: a 1:5 scale model of the front bonnet of a Ferrari 250 Testa Rossa from 1958 and a head lamp housing of a Ferrari 275 GTB from 1962. Considering the complexity of double curvature surfaces and the reflection due to material and surface treatment, both these artefacts require some pre-processing operations and an adequate set-up to perform image acquisition. These case studies represent a relevant application for the field of classic vehicle restoration, where C-RP could be a promising technique to support panel beaters and craftsmen during rebuilt operations of masks and bodywork spare parts of high-end historic cars.

Keywords: 3D capturing , 3D digital model , car body panel , Classic vehicle restoration , Close-range photogrammetry , Geometric inspection

This paper presents a systematic approach to model and simulate the influence that the variation of process parameters has on the final quality of an injection moulded component. In the first phase, we define a multi-steps procedure to develop a reliable digital model of the injection moulding process by the fine-tuning of the part cavity and the mould elements (e.g. detail simplification, discretization and mesh density, elements modelling, etc.) using real data as validation. In the second phase, we investigate the correlation between selected process parameters and the final tolerances of the moulded component, based on a Design of Experiments. As a case study, we selected the body of a mass airflow sensor for an automotive high performance engines, made of polybutylene terephthalate reinforced with glass-fibre, which presents roundness issues on functional features. The effects of the injection velocity and packing pressure on the deformation of the component are investigated, identifying the best combination of their values that leads to compliance with the roundness tolerances on its functional features. The injection moulding Computer Aided Engineering (CAE) software Moldex3D (CoreTech) is used to run the simulations, and the results are finally validated by comparing the experimental data obtained from the injection moulding machine that produces the component.

Keywords: Design of Experiments , Injection moulding , Simulation-based design approach , Tolerances , Warpage

A die for Al alloy casting must be designed to achieve the expected quality levels. Moreover, the casting unit cost must be regarded as the objective function to be minimised. It can be expressed as a function of the quantity of materials and energy to be used, cycle time and equipment investment. This work compares the performance of the die with inserts manufactured using the usual 1.2343 steel with that of the innovative 1.2383. The latter is considered due to its enhanced thermal conductivity, despite being more expensive. Simulation experiments are designed to evaluate different die layouts. The quality design solutions are evaluated against the cost objective function in order to identify the optimal die choice. A case study on gravity die casting (GDC) of an AlSi7Mg0.3 engine head shows faster solidification dynamics when using 1.2383 instead of 1.2343 steel. This reduces the feeder volume, thus increasing the production yield and speeding up the cycle time with a leverage effect. The higher investment cost for the inserts is rapidly returned thanks to the reduction in variable costs. The Return On Investment (ROI) with the improved die in the new solution is short compared with the life of the die.

Keywords: Cost optimisation , Cycle time , Gravity die casting , Material selection , Process yield , Steel conductivity

The main aim of this article is to describe the design of a new sensor to study the electromagnetic field portions of gravitational waves. On August 17, 2017, the observation of the gravitational wave event started the era of multi-messenger astronomy. Therefore, new tools and optimal synchronization of the available telescopes are needed. The sensor that is designed is a cross-cutting technology, it is named Crystal Eye: a wide field of view in the energy field from 10 keV to 10 meV with a structure made of pixels. As the detector will be involved in the mission in 2023, the virtual prototype phase needed for optimization and production of the payload has been completed. Particular attention was paid to the results of the FEM analysis carried out to examine and predict the thermal and vibration behavior of the conceived mock-up during the launch phase and under strong temperature variations in the space environment.

Keywords: Detector , FEM , Vibration and thermal analysis , Virtual prototyping

Designing highly usable and ergonomic dashboards is fundamental to support users in managing and properly setting complex vehicles, like trains, airplanes, trucks and tractors. Contrarily, control dashboards are usually intrusive, full of controls and not really intuitive or usable. This paper focuses on the design of ergonomic and usable dashboard for specific classes of vehicles, like tractors and trucks. Indeed, trucks and tractors are both vehicles and operating machines, and their control is particularly complex. Indeed, the driver contemporary drives and checks if the machine is working properly. The paper proposes an innovative methodology to design highly usable and compact dashboards inspired by human-centered design and ergonomics principles. The study started by shifting the attention from the machine performance, that is the conventional engineering approach, to the human-system interaction quality, according to a new, transdisciplinary approach. The methodology proposes to combine virtual simulations with human performance analysis to support the design at different stages, from concept generation to detailed design, until testing with users. The methodology uses virtual environments to create digital twins of both driver and controls, making users interact with virtual items and predict the type and nature of interaction. Within virtual scenarios, different configurations of dashboard controls can be easily compared and tested, checking the frequency of use of each control and measuring the achieved human performance related to postural comfort and mental workload. The study adopted the proposed methodology to two industrial use cases focusing on the design of ergonomic dashboards: the former is referred to tractor dashboard and armrest, the latter refers to truck dashboard and seat. Both cases demonstrated that the new methodology allowed improved comfort, higher usability, higher visibility and accessibility, better performance and reduced time for machine control. The study demonstrates how a multidisciplinary user information integration can drive design optimization.

Keywords: Ergonomics , Human factors , Human-centered design , Usability , Virtual simulation

This paper introduces a method to prepare an engine for very long flights without maintenance. It also gives criteria to estimate time between overhaul by using the sensor data to have an estimation of the engine condition. In-flight refueling has introduced new challenges to UAV (Unmanned Aerial Vehicle) propulsion systems. It is now possible to run continuously an UAV without landing for long periods. For this task, it is necessary to carry a quantity of lubricant sufficient for at least one month (approximately 800h). For extremely long flights, diesel piston engines are better than spark ignition ones due to extremely low fuel consumption. A selection in the assembly line individuates those engines that are suitable for long endurance flight. This is possible because automotive engines are manufactured in thousands per day and many quality controls take place in the assembly process. Moreover, mass produced automotive engines pass several tests during the assembly process including a very short run. The results of these tests are useful for an initial selection. Then, a 25-hour trial with a very thin lubricant is sufficient to forecast the oil consumption up to 1,000 hours. The 25 hours run corresponds to the time necessary to stabilize the oil consumption rate. In addition, during the 25 hours run also the electronic infancy failures are detected. In modern engines, the electronic on board diagnosis, the full redundancy of vital sensors, electronic control units and batteries/generators, make it possible to fly safely without emergencies with random electronic failures of components and wiring. Another major requirement is to forecast the engine failure or an unacceptable deterioration in terms of mechanical performance. This paper introduced a method to evaluate the state of wear of the engine starting from a digital monitoring system. A wear model of the engine based on the real duty cycle is proposed. It is then possible to prolong the life of the engine and to increase the time between overhaul. It is also possible schedule the overhaul operation

Keywords: 800h flight , Aircraft , Piston engine , Tbo evaluation

This paper introduces a practical design procedure for Direct Metal Addictive Manufacturing (AM) by Hybrid Selective Laser Sintering or Melting (SLS/SLM). Theoretically AM frees the designer from many design constraints, practically it introduces new problems and it requires a brand new design of the part. Hybrid manufacturing reduces the problems without solving them totally. Supports can be introduced but represent a waste of time during manufacturing and during the post-mill removal. Before a 3D-printed metal part becomes usable, it has already undergone significant postprocessing in the form of CNC milling, hot-hyping, shot-peening or sand-blasting. Powder-bed fusion parts shows a quite rough surface finish. Considering that post-milling will be necessary in any case, surface finish is less important than other issues metal 3D printing. For example, very small cavities form within the part as it is being built. These defects lead to cracks during the part life cycle. Too few power applied by the wiper, too low laser intensity, excessive or inefficient cooling are the most common causes. Geometry of the part, optimized printing pattern and machine parameters are used to address these problems. AM machine operators have to tune their machines for a given material and print job. In the SLS/SLM process, density is achieved with quality powders, optimized build parameters and controlled machine environment. Hot isostatic pressing treatment as a post-process removes the porosity and reveals excessive defect by deforming the part. Residual stress is a result of the printing process. As the powder is melted and cooled, expansion and contraction occur. The residual stress is compressive at the center of the part and tensile at the boundary surfaces. Therefore, thin walled continuous parts are to be preferred. In fact, the classical ribbed structure has several thickness discontinuity requiring continuous adjustment in the build pattern and in laser modulation. To ensure the quality of the part material, the initial layers of the print are removed via CNC milling after the build is complete. Unfortunately, the thermal stress of the substrate will cause the part itself to warp modifying its geometry. Support structures are positioned in the right locations to prevent distortion or warpage. In addition, overhanging surfaces or down-skins faces have poorer surface finish ad are subjected to warping. For this reason, they also need additional supports. For these reasons, the Direct Metal AM part may have a completely different geometry than a cast component. An example of redesigning of a PSRU (Power Speed Reduction Unit) is provided in this paper.

Keywords: Aircraft , Direct metal additive manufacturing , Gear drive , Helicopter , Housing , Psru , Transmission

On-demand air transport is an air-taxi service concept that should ideally use small, autonomous, Vertical Short Takeoff and Landing (VSTOL), “green”, battery-powered electric aircraft (eVSTOL). In addition, these aircraft should be competitive with modern helicopters, which are exceptionally reliable machines capable of the same task. For certification and economic purposes, mobile tilting parts should be avoided. The concept introduced in this paper simplifies the aircraft and makes it economical to build, certify and maintain. Four contrarotating propellers with eight electric motors are installed. During cruise, only two of the eight rotors available are not feathered and active. In the first step, a commercial, certified, jet-fueled APU and an available back-up battery are used. A second solution uses a CNG APU and the same back-up battery. Finally, the third solution has a high-density dual battery that is currently not available. A conceptual design is shown in this paper.

Keywords: attitude control , cost-effectiveness , electric–thermal hybrid aerial , vertical short takeoff landing

Delicate grasping of complex diverse objects is a challenging task for underwater vehicles, such as remotely operated vehicles (ROVs). In this article, a novel controllably compliant soft robotic underwater gripper is presented, which uses two neutrally buoyant particle jamming pads to safely and securely grasp arbitrarily shaped objects, including fragile and/or massive targets. Antagonistic low-friction rolling diaphragm hydraulic cylinders are used to control the compliance of the jaw closure to passively limit the total force applied during the approach. The antagonistic hydraulic cylinders also compensate for the volume reduction of the pads during the jamming process while still enabling rigid grasp during manipulation. Soft finger-like fiber-reinforced actuators are used to maintain the shape of pads without introducing rigid elements. Force limitation is demonstrated by the ability to pick up fragile objects without breakage and to surround soft targets without excessive deformation of the object. We present the overall design, experimental setup, and in-water testing using a compact ROV-based hydraulic drive system. The resulting system has demonstrated capability for grasping a diverse range of objects that vary widely in terms of weight, size, and geometry, largely enabled by the hybrid design of soft grippers guiding jamming pads into optimal configurations.

Keywords: Actuators , Fiber-reinforced actuator , Force , Grippers , Hydraulic systems , Jamming , jamming gripper , low-friction hydraulic transmission , Manifolds , remotely operated vehicle , Shape

Heavy fuel combustion problems with startup and operation may significantly reduce the microturbine efficiency in small APUs (Auxiliary Power Units). The use of commercial automotive-derived turbochargers solves the design problems of compressors and turbines but introduces large issues with combustors. The radial combustor proved to be the best design. Unfortunately, high-pressure injection is not practical for small units. For this reason, primary air and low-pressure fuel spray are heated and mixed. In any case, a high air swirl must achieve a satisfactory combustion efficiency. This swirl should be almost eliminated at the turbine intake. CFD analysis of the combustor design was, therefore, performed with several different geometries and design solutions. In the end, a large offset of the fresh pipe from the compressor proved to be the best solution for a high swirl in the combustion region. The combustion tends to eliminate the swirl, but an undesired tumble motion at the turbine intake takes place. To eliminate the tumble, two small fins were added to straighten the flow to the turbine.

Keywords: APU , combustor , micro-turbine

Additive manufacturing is even more capturing the interest of vehicle manufactures. Its adoption enables design potentials such as parts customization, lightweighting or functional integration. Deep adoption of additive manufacturing and integration of topology optimization design techniques enable the calculation of light components, while additive manufacturing makes it feasible by adding subsequent layers of material. Design for additive manufacturing guidelines address these challenges by enabling the build of such complex shapes thanks to parts consolidation and features integration. Several prototypes of such lightweight design concerning chassis, body, and structures have been provided, but the lack of structured and objective approaches limits the application in normal production. This work integrates Key Performance Indexes (KPIs) into the Design for Additive Manufacturing (DfAM) approach for an effective adoption of selection of trade-off studies for the selection of best product variant and process setup. The trade-off involves KPIs related to structural product requirements and laser Powder Bed Fusion process cost estimation, to return functional components that address the best ratio between weight reduction and expected manufacturing cost. Proof of the method effectiveness and its application to lighten real components is demonstrated by applying the approach to reduce the weight of a steering support system for a Formula SAE race car. The objectivity of the trade-off promotes the extensive adoption to other vehicle components for substantial fuel efficiency improvement and emissions reduction perspectives.

Keywords: 3D printers , Cost estimating , Economic and social effects , Emission control , Integration

This work aims to develop a mathematical model for the simulation of a fuel cell (FC) hybrid powertrain. The work starts from modeling a single cell to obtain information on the entire FC stack. The model obtained was integrated into a simulation tool presented in the literature that simulates the longitudinal dynamics of auxiliary power unit hybrid electric vehicles and fully electric vehicles. Therefore, the integrated model allows the simulation of hybrid vehicles equipped with FC and a battery pack that acts as a peak power source. The tool simulates the mechanical and electrical behavior of the vehicle, introducing an investigation of the power flows relating to the FC and batteries. An appropriate power split logic has been implemented, allowing the correct management of the power distribution between the FC and the batteries. The importance of analyzing FC vehicles' behavior arises from the recent necessity to find alternative propulsion systems, overcoming the range problems associated with fully electric vehicles. The innovation lies in the versatility and modularity of the model, which is open to modifications and features a low computational burden, making it suitable for testing new solutions by performing first design and sizing calculations.

Keywords: alternative propulsion , control strategy , energy consumption , mathematical modelling , performance prediction