The Finite Element Analysis And Structure Optimization Of Sedan Car Suspension Control Arm

In the optimum design of vehicle suspension system, the properties and their matching of main components have crucial effects on suspension and vehicle behaviors. In addition to ensure the vehicle performance such as riding and handling stability, the structural strength, rigidity and weight etc also have to be considered, so as to make the suspension not only be able to reliably transmit the force and torque between vehicle body and wheels, to ensure safety, but also not excessively increase in vehicle weight and cost of production, to ensure fuel economy. Although the finite element method has been widely used in the structural design of vehicle components, but solely use this methods to improve the design of structure may be blindfold, especially for the suspension components with complex shapes and boundary conditions, it needs to be combined with a variety of other analytical methods.For these reasons, this paper is mainly to realize the suspension components'lightweight request of a certain sedan car chassis development project, integrately use multi-body dynamics, finite element and structure optimization method to study the finite element analysis and structure optimization of a conceptual suspension control arm. After a brief introduction of the virtual prototye, finite element and structure optimization methods'applications in vehicle design home and abroad, a load analysis of suspension control arms was carried out. And then the loads were used as the boundary conditions for the strength analysis of a conceptual control arm, a free modal analysis of the arm was done synchronously. Finally, the structure of the conceptual control arm was optimized and the arm's performance that before and after optimization was compared. Specific research and conclusions of this paper are as follows:Firstly, load analysis of suspension control arms: First of all, four kinds of methods that about how to obtain the load bondary conditions of suspension components were summarized and compared, and decided to adopt a simulation of the suspension's multi-body dynamic model to obtain control arms'loads. Then the limit working conditions for load analysis were summarized, and grounding forces at these conditions of the tires were calculated. Finally, simulation of the suspension's ADAMS rigid-flexible coupling model was carried out, using the grounding forces as input conditions. And then the control arms'loads that from typical working conditions were extracted, and the loads could be reliable boundary conditions for the follow-up suspension control arms'finite element analysises. In this process, the reference coordinate system of control arms'loads was discussed bat around, and the conclusions were used at the process of loads extracting.Secondly, finite element analysis of control arm: First of all, according to the principle of geometric clean-up and mesh compartmentalization, the selected conceptual control arm's finite element model was built up using hexahedral element in HyperWorks software environment. Then build a reference coordinate system accord with the system that build in load analysis, considering the control arm as a moving components, and the relief methods, select of virtual support etc were explained in detail. The results that obtained through solving structural strength, rigidity calculation results show that: there is a big redundancy of material in the conceptual design, and it is necessary to optimize the structure of this design. Finally, a free modal analysis was executed for the control arm, based on the comparison of different types of modal analysis. Analysis results show that: the natural frequencies of this arm are far away from some incentive frequency range that may come in for this sedan car, so the natural frequency may not be a consideration of the structure optimization.Finally, structure optimization of control arm: Respectively, chose topology and shape optimization as the conceptual and detailed optimization methods for the control arm, considering this arm is a solid component and has a big redundancy of material. In the round of the topology optimization process: first of all, the optimization objective, constraint conditions etc were explained in detail, such as the drawing constraint and so on. Then the the results of the optimization was improved by considering the structural requirements of contour forgings. Finally, strength and free modal analysis was carried out for the ameliorative design, the results were compared with the conceptual design. In this round of optimization, a total of 13.69 percent redundant material was abated from the original design, and the lightweight effect was prominent, whereas structure's strength and rigidity was reduced a little, it is necessary to be further optimized. In addition, the natural frequency is only slightly reduced, and it is not necessary to be considered in the follow-up shape optimization. In the second round, the topological design of the control arm was optimized by shape optimization method. The final meliorative design was selected by comparing the results under different constraints, strength and modal analysis was executed on the instant. Comparing to the original concepte design, the final design was abated a total of 16.34 percent redundant material, and the structure's strength and rigidity was enhanced. Athough the natural frequencies were slightly reduced, it could meet the application requirements. The objective that to reduce component's weight but not to sacrifice performances was basically achieved.Through the study in this paper, obtain one kind of solution on suspension control arms'structure design. This solution was changed from traditional experience or semi- experience design to hodiernal virtual-prototype-based design, and the objective that to enhance product design level, reduce product costs, improve product performance, enhance product competitiveness etc was achieved. Therefore, this study has good practical significance.