Lightweight Design Of Multi-material Auto Body Based On Hierarchical Iteration

Automobile lightweight design is now an important current of the global automotive industry,which is also one of the technologies for energy saving and new energy vehicles.And multi-material auto body design is a field of large potential in automobile lightweight design,which integrates structural design,lightweight materials and advanced technology,thus it is still of great difficulty to develop now.Based on the work of our group and the study of other scholars in multi-material auto body design,a novel methodology based on hierarchical iteration is presented.Topology parameters(locations and number of joints)in assembly synthesis are taken as design variables,which expands the design domain considerably,simplifies the original optimization problem and a better solution can be obtained.In order to solve the coupling between topology parameters and other parameters,topology parameters are placed in the first level to maximize the structure performance(such as bending stiffness and torsional stiffness),while the other parameters are placed in the second level to minimize the mass and material cost of the structure on condition that structural performance of the auto body are not decreased.Eventually,the two levels are repeated to accelerate the convergence of the methodology and the final optimal design can be selected with the scoring method.A multi-material underbody design problem is conducted at the end of this article and an optimal solution is obtained which satisfies all the constraints.The result of the case study and curves of the objectives certify the feasibility and effectiveness of this method and the multi-material design obtained can server as a reference for engineers in the conceptual design phase of an auto body.