The Research On The Lightweight Of Passenger Car Based On The Structure Optimization Design

The weight of skeleton is one of the most important components in the passenger car, because it is about a quarter of the whole vehicle. Lightweight of skeleton can not only save materials, but also improve driving force and fuel economy and reduce engine emission, so it is of great practical significance. To achieving lightweight has two kinds of ways, one is the optimization design of skeleton structure and the other is use of lightweight materials. The thesis uses the first kind method by using the software of CAD/CAE/CAM——I-DEAS to finite element analysis.Firstly, based on the results of the predecessors and all kinds of reference, the paper discussed the importance of the automotive lightweight from the two aspects of energy conservation and environment protection. The current status of research on lightweight to passenger cars at home and abroad were introduced in this paper, and the ways to lightweight of passenger car were summarized.Secondly, taking the type of GDW6850H passenger car as an example to building the finite element model for the body skeleton which its surface was covered for a semi-bearing type, through using the FEA software I-DEAS and reasonable simplification. Then analysis the stress distribution and displacement of passenger car under two typical working load states including static bending and static twisting, so the weak points and the strong points of the structure had been found, and the result were useful for the lightening. Furthermore, the dynamic characteristic of the structure had been analyzed in order to getting the information of the frame. The ten orders natural frequencies had been calculated and low-order vibration shape of the body structure was studied.At last, The Optimization module of I-DEAS was taken to obtain the lightweight optimized of body skeleton. In the process of optimization, the total mass of the body skeleton was designated as an objective function, the thickness of outer covering and the cross-sectional area of nine major body beams which was deeply influenced to the total mass was designated as a variables, the stress maximum value,displacement maximum value and body's low-order natural frequencies as state variables. After optimization, the lightweight of this passenger car body is about 135.54 Kg on the condition that the performance of the passenger car meets the requirements and conforms to the national related standards. The anticipated goal is achieved.