Multidisciplinary Design Optimization And Lightweight Research Of Trussed Crash-resistant Body Integrated Material And Structure

Energy saving and emission reduction have become important development goals for the automotive industry.Lightweight is one of the main ways to achieve energy saving and emission reduction in automobiles,and the collaborative research of crash safety,ride comfort and lightweight is getting more and more attention.Aiming at the problems that the deformation of passenger protection zone is too large to protect the passengers during the collision,the material of non passenger protection zone is not conducive to lightweight,NVH characteristics and collision safety performance conflict with lightweight,a multidisciplinary design optimization and lightweight framework of trussed crash-resistant body integrated material and structure is proposed.The research contents of this paper are as follows:(1)A multidisciplinary design optimization and lightweight framework of trussed crash-resistant body integrated material and structure is proposed.With the truss body as the research object,the multidisciplinary design optimization framework of truss body multi-material crash-resistant structure is constructed by optimizing the load path,structural crashworthiness evaluation and material replacement,and collaborative optimization based on robust design,so as to quickly match the overall vehicle performance such as crash safety and NVH while achieving lightweight.(2)An optimized trussed body structure based on load path is proposed.The geometric model and the 100%frontal crash finite element model of FSEC body with single material and equal wall thickness are established for crash simulation.The equivalent static load structure optimization method is used to transform the dynamic nonlinear problem into static linear problem in the collision process.The load path of racing body is analyzed and improved to reduce the structural deformation of passenger protection area and improve the protection of passengers.(3)A crashworthiness evaluation and material selection strategy for trussed body is proposed.According to the material index,the database of alternative materials is established.The progressive structural optimization method is used to evaluate the crashworthiness of truss body members,and the computer sorting algorithm is used to select materials iteratively according to the evaluation results.On the premise of ensuring the collision safety of the body,the crashworthiness and material properties of truss body members are reasonably matched,the results show that the material distribution of multi-material body is as follows:Aluminum alloy accounted for 60.05%,high strength steel accounted for 31.14%.(4)A multidisciplinary design scheme of trussed body structure is proposed.In order to ensure the safety,the energy absorbing block is installed.The influence mechanism of cellular length of honeycomb aluminum energy absorbing block on energy absorption and compression is analyzed,and the structure scheme of energy absorbing block is determined.Aiming at multi-material FSEC racing body with equal wall thickness,a collaborative optimization method is used to obtain a deterministic optimization scheme which could balance the conflict between NVH performance,crash safety performance and lightweight.Robust design is carried out by using 6 Sigma theory,and the NVH characteristics and crash safety performance indexes of the racing body exceed the 6 Sigma level,the difference between the vibration frequency of the first mode and that of the excitation source is 5.33Hz,and the mass of the trussed body is reduced by 54.54%compared with that of the multi-material racing body.