Robust Optimization Design Of Electric Vehicle Battery Enclosure

In this paper, an electric vehicle traction battery enclosure was studied at the background of vehicle lightweight. Base on the finite element theory, the structural roubust optimization design of the traction battery enclosure was conducted by topology optimization and shape optimization technology. The dynamic and static performance of the traction battery was improved and lightweight was achieved. The main study contents and conclusions were as follows:Firstly, the finite element analysis model of the traction battery enclosure was established based on the basic theory of continuum structural topology optimization method. The key techniques of the finite element modeling were analyzed and summarized, including model simplification, geometry cleanup, meshing regulation and quality control, etc. Some simulation methods for welding and bolt connection were compared and discussed. An ideal finite element model was established.Secondly, the modal characteristic and static characteristic of the traction battery enclosure were conducted using the finite element analysis method. Modal analysis was mainly aimed at calculating the first six free modes and constraint modes. Static analysis was focused on the stress and deformation of the structure under five typical load conditions, which were the vertical, left turning, right turning, forward braking, reverse braking.Then, the deterministic topology optimization design of the traction battery enclosure was carried out using the continuum structural topology optimization method. The dynamic topology, static topology and multi-objective topology were conducted under four multi-regional schemes. The purpose of the dynamic topology optimization was to improve the first five natural frequencies of the structure. The goal of the static topology optimization was to improve the structural stiffness under the five typical load conditions. The multi-objective topology optimization was aiming at improve the structural stiffness and the natural frequency at the same time.Finally, the robust optimization design of the traction battery enclosure was conducted. The sparse grid technique based robust optimization design method was proposed, and based on the theory of probability analysis, the robust objective function was processed into a linear weighted combination of the mean and the standard deviation of the target function. The robust topology optimization calculation under three kinds of accuracy was carried out. At the same time the shape optimization was applied to achieve two new structures. Considering the processing technology requirements, the two new structures of the battery enclosure were reconstructed. By comparing with the original battery enclosure structure, the dynamic and static performances of the new structures are improved while the mass reduced by 7-10%.