Topology And Size Optimization Designing For Body In White Of New Energy Vehicle

Compared with the traditional fuel vehicles, New Energy Vehicles (NEV) with more energy efficiency, lower pollution and other advantages, once again become a hot research and development of the world. At present, some new energy vehicles are still used traditional vehicle body structure, only the power system replaced. NEV’s power-driven part is motor replaced the engine, increasing the battery, which would inevitably lead to the changes in the body. These lead to a big difference in the structure design to traditional fuel vehicles and new demands on the body structure design. On the other hand, the simple power systems make lighting weight greater space. Therefore, it is a worthy and important study to design new energy vehicle body structure to match the power system lightweight body. Structural topology optimization technology can make these come true.Based on the features of the NEV, topology optimization and size optimization to NEV with SIMP (Solid Isotropic Material with Penalization) method, which is currently the most widely used in many kinds of topology optimization problems because it is very easy to be implemented and fits for many kinds of optimization problems. This paper presents a mathematical model for topology optimization of vehicle Body-In-White (BIW) to minimize the structural compliance based on Solid Isotropic Microstructure with Penalization (SIMP) method. Design sensitivity of BIW structural compliance is analyzed and the filtration technique of sensitivity is applied in solving the numerical instability problems that may arise during the optimization process. Based on load analysis of a NEV body, topology optimization is carried out for BIW of the NEV under static load, bending and torsion, respectively, with volumetric and geometric constraints simultaneously. Bending and torsion rigidity of the designed BIW are optimized by size optimization and tested using wireframe model based on topology optimization results. The results of numerical examples show that topology optimization based on SIMP method can be employed for BIW design of NEV with practical engineering application without design domain. The designed BIW structure can meet design requirements of body rigidity while achieving lightweight.