Floor Structure Concept Design Of Car Body Based On Multi-level Optimization Method

Nowadays, with the vigorous development of automobile industry, people’s life quality are also gradually improve, everybody began to more tend to focus on the car’s riding comfort, security performance, fuel economy and so on. Automotive lightweighting is an important tendency for development of automotive industry today, how to balance the contradiction between the various performance and lightweight problem has become a key research field in recent years. Floor structure as one of the most important part of the car body, play the role of bridging engine compartment and baggage compartment, and carrying the crew compartment, floor structure performance will decide the vehicle stiffness, strength and shock resistance. So, design and optimization the body floor structure for whole body structure performance and lightweight has the vital significance.This thesis was investigated using finite element analysis (FEA) method. First of all, the simulation model of concept car body structure based on beam element is modeled, and the results of the model in concept match well with the results of the model in detail, which verifys the accuracy of the modeling method, and many effect factors which control the floor structure like the topology of the floor beam and connection position of floor beam, are analyzed. It was found that the structural parameters interact with each other in affecting the structural performance of the car body, and we can seeking the optimum design by numerical optimization. In order to solve the relationship between two design variables of factors affecting, Multi-level optimization method is introduced into the floor structural design of car body, through the hierarchical optimization of floor beam topology structure and floor beam connection position, and through the conversion of optimization goals and design constraints between different levels, the multi-island genetic algorithm(MIGA) algorithm was used to seek the optimal solution sets in the process of floor design which is rebuild, based on the results, some optimal designs under different boundary conditions were obtained, through compared with the original body structure before optimization, the optimized structure improved the performance of car body structure on the premise of few quality increased, through comparison of the performance of specific stiffness can be seen that the optimized performance improved.The paper brings multi-level optimization method into car body floor structure design process, and fully verifies its accuracy and practicality, so it has a guiding significance for actual parameters research to design the floor structure of car body.