Nouveau concept de carter de boite de vitesses allégé en aluminium et plastique en utilisant l'optimisation topologique multimatériau

Lightweight materials and innovative designs have always been an important topic in industrial product development. Among others, constraints on energy consumption and CO2 emissions, efforts to improve resource efficiency as well the continuous search for increasing the range of EVs and their dynamic behavior have greatly stressed the importance of this topic over the last years in automotive. A dedicated Interreg project entitled LightVehicle 2025 (LV2025) has been launched in the Euregio Meuse Rhine (EMR) region since 2018 to develop four demonstrators exhibiting the best technologies mastered in the Region in this field. The project partners have selected four demonstrators revisiting typical vehicle components to highlight lightweight technologies. A consortium of industrial partners has been built around each demonstrator to support all steps of the component redesign from preliminary design, virtual prototyping and simulation, pre series prototyping and testing, virtual manufacturing and mass production. The present work focuses on the redesign of an electric vehicle gearbox rear cover. Traditionally produced by aluminum and die casting, the gearbox cover offers a good opportunity to showcase the lightweighting potential in powertrain components. A two materials design (aluminum and plastic) is explored to take advantage of the complementary properties of the several materials. A multi-material topology optimization (TO) is used to exhibit innovative designs. Several TO results, with different combinations of volume fractions of each material, with or without stiffeners, give a valuable insight on how the new part should be redesigned. Several alternative layouts are also proposed. The metallic material is used to act as stiffness skeleton while plastic material offers skin functions as oil containment. The plastic material used in this study belongs in the family of styrene maleic anhydride (SMA) copolymers and is glass fiber filled. In a second step, injection insert molding is chosen to produce the new concepts based on the TO results. Given the fabrication process, a concurrent work between designers and fabrication experts is carried out to adapt the topology optimized layout to cope with the limitations of plastic injection process. Appropriate mechanical interlocks are added to ensure the impeccable connection of the two materials. The injection insert molding is simulated while the filling and warpage behavior is investigated. Subsequently, a final structural analysis on the resulting part is performed as a final assessment stage, taking into consideration the simulation findings such as the real fiber orientations. Finally, the weight reduction achieved with this new concept is well within the -25% as requested by the target of the project. In addition, a LCA analysis is also performed showing that the new multi material design falls well over the expected 25% reduction of the CO2 emissions too.Lightvehicle 202

An overhang constraint adaptable to a proper building orientation

peer reviewedIn additive manufacturing processes, the critical overhang angle of downward facing surfaces limits printability of parts. To consider this limitation of the process in topology optimization, several approaches have been proposed in the literature. Most of them operate with a user-defined building direction, thus, if the orientation is not appropriate, structural performance could be drastically compromised. This work aims to reduce the dependence of the user on the definition of the building direction. We make use of a gradient-based constraint due to the low computation cost it demands in comparison to layer-by-layer approaches. The method is demonstrated on 2D and 3D examples.Aero

Une approche générique pour capitaliser l'expérience en conception et en optimisation

peer reviewedAs design changes in the production phase can be hundreds of times more costly than in the design phase, it is crucial to make sure that the designed product is actually manufacturable before start of production. To this aim nowadays often many manual iterations are needed between the designers and manufacturing experts, which leads to an inefficient design process and delayed time-to-market that in turn are detrimental for company competitiveness. Here we present the outline of a research effort to realize a substantially more integrated design process tailored towards both performance aspects and manufacturability. Key to this is the formalisation of Design for Manufacturing (DfM) rules within the functional CAD design stage. The traditional design approach is exemplified further in this work for the design of a gearbox housing for electric vehicle transmission systems. To realize substantial weight reduction without compromising performance, a novel multi-material design is proposed, constituting of both aluminum, to ensure structural integrity, and high performance polymer for additional structural integrity and leak-tightness under operating condition. Results shown include Topology Optimization (TO) under realistic loading conditions, scrutinizing material volume fraction boundary conditions and mesh sensitivity. Finally, some DfM rules and considerations in order to come to a manufacturable CAD design, are highlighted.Lightvehicle 202