Finite Element Analysis And Optimization Design On Vehicle Frame Structure

The finite element method is an efficient and effective kind of modern engineering design aids. The finite element method used in the automotive structural design will bring us dramatic effect in many aspects,including improving the vehicle static and dynamic characteristics, optimizing the body and frame of the vehiche,shorting the development cycle of new cars, saving research and development costs. The frame which is a vehicle chassis and vehicle load-bearing matrix supports all kinds of complicated loads coming from the road and freight. So the performance of frame structure determines vehicle quality.In this paper, combining the actual project and using CAD/CAE related technologies,finite element analysis and optimal design are used in an off-road vehicle frame. Through conversing and importing geometric model, extracting midsurface,cleaning up geometry, dividing into grids, controling quality of the elements, setting up the high-precision and high-quality analysis model of the vehicle's frame by taking shell unit as basic unit by using HyperWorks software.Through tensile testing,the stress-strain curves of frame's parts are obtained. According to the actual traffic load conditions and setting the corresponding loads and boundary conditions,bending stiffness and torsional stiffness which are based on the finite element model are analyzed. The results show that the stiffness of the frame to meet the design requirements, and there is room for improvement lightweight.The model analysis of the frame is studied. The mode vibration model and proper frequency of the frame are calculated by mode analysis. The dynamic characteristic is considered by the frequency and the model. Then,based on static and dynamic analysis of the frame,using the thickness of the parts on frame as the design variables,reducing the frame weight as the target, under the stiffness index and frequency to meet the requirements, establishing the size of the frame structure optimization model and get the light quantization design result. Finally, the structural topology of the frame is carried out by using OptiStruct software.This paper apply a compromise programming method to establish a mathematical model of multi-objective topology optimization, while mean frequency method is adopted to settle eigenfrequencies of free vibration optimization. Take an off-road vehicle frame for example, a reasonable topology structure of frame which meet the compliance and eigenfrequencies request at the same time is obtained based on this approach. Both the theoretical analysis and the application result indicate that the new structural design is rational, thus proving the effectiveness and feasibility of this method, which provides a new idea for frame structure topology optimization design.