Finite Element Analysis And Experiment Study On Aluminum Alloy Wheel Structure

Wheel is an important safety component of vehicle driving system. Since all driving force of running vehicle is transferred through wheels, the performance of wheel structure is very important to the safety and reliability of the vehicle. In order to meet the requirements on strength and fatigue, ISO, JASO and GB all prescribe that aluminum alloy car wheels must do bending fatigue test, radial load fatigue test and impact test. In the past, the design of wheel mostly depends on experience. So there are a lot of shortages, such as blindly design, long design and manufacturing period, high cost, and so on. In face of the increasingly stinging competitions, enterprises cry for new scientific design method. The background of this research is the cooperative project "Aluminum wheel weight optimization design and development" between Zhejiang University and Zhejiang Wanfeng Auto Wheel Company. This dissertation focuses on the finite element method using in wheel structure design. The proposal of weight optimization and structure modification can be aroused through the finite element analysis (FEA) result which solved the shortage of traditional wheel design method.In order to achieve the objective of this research, according to the theory of numerical simulation of solid mechanics (including elastic mechanics and impact dynamics), by a way of combining real test on wheel and experimental stress analysis method, the FEM of bending fatigue test and 13°impact test were established, and verified through experiments. When establishing the FEM of bending fatigue test a transient load function was used to simulate the rotatory bending moment, the stress distribution in the wheel under this load was obtained. When establishing the FEM of impact test a half-sine function was used to define the impact load, after normal mode analysis the dynamic response analysis on impact test was elementarily realized.First of all, static elastic FEA was done on three performance test of aluminum alloy wheel. The material property of wheel used in FEA was measured on specimens taken from the real wheel. When doing static elastic analysis, only the modulus of elasticity E and the Poisson's ratioμwere set as the material parameters. When the maximum stress in the structure is lower than the yield strength of the material, static elastic analysis is usable to calculate the stress distribution in the structure under test condition. And the result can be used to guide the structure optimization of wheel. For impact test static analysis two load calculation methods were considered, one is using dynamic load coefficient and another is calculating the transient maximum impact load. The results of two ways were compared and the way by calculating the maximum impact load is more reasonable.But bending fatigue test and impact test of wheel are both dynamic tests. So it isnecessary to establish a dynamic FEM. First, mode analysis of wheel under bendingfatigue test and impact test condition was separately done. The mode vibration modality ofwheel structure was analyzed. Then the dynamic analysis of wheel under rotatory bendingmoment was done, and the stress in the wheel during bending fatigue test is not asymmetrical one. To compare the different working principle of two kinds of bendingfatigue test machines, stress distribution of wheel under centrifugal force was analyzed.And the result shows that the test result with these two different machines should be same.After doing mode analysis to wheel structure under impact test condition, referring torelated literature, dynamic response analysis on wheel's impact test was done with anassumption that the impact load meet half-sine function. Since the I-DEAS software has twoassumptions (1. impact occurred at the beginning of event; 2. the persistence timing is tooshort, so can be neglected.), when doing initial impact analysis, this dynamic responseanalysis was a response analysis after the impact. The displacement, stress, velocity andacceleration response of wheel structure after impact were analyzed. These results are usefulto judge the strength of wheel design and to optimize the wheel design. But to build acompletely accurate FEM is still difficult because there are tyre big deformation, gas-solidcoupling and contact issues in wheel's impact test. To solve this difficult problem is thekeystone of future study.Using dynamic resistance strain gauge and the data collection instrument, based on the theory of electricity measurement method, the real stress of wheel structure under bending fatigue test and impact test were separately measured. Data mining was done on the stress data using artifical neural networks method. The stress measuring result of wheel in bending fatigue test shows that the FEM on bending fatigue test established in this dissertation was correct. The stress in wheel structure under bending fatigue test can be correctively reflected by the FEA result. The measuring stress result of wheel structure under impact test shows that during impact test there were 6 obvious wave crests on the stress wave of the wheel structure. As a transient process with big displacement and big distortion, there are many unlinear issues, such as geometry, material and contact. So the measuring results are very precious and have directive meaning to increase the digital simulation precision.Experimental stress analysis and limited fatigue life test were done using one kind of wheel as an example. A stress and fatigue life curve based on the FEA result and experimental test result was planned to set up which can be used as a judgment basis when predict the fatigue life of wheel based on FEA result in the future. Using a wheel structure designing process as an example, from the original design, FEA, weight optimization ways to final design, several typical way to optimize the weight were described. A target weight of weight optimization on different size wheels was brought forward.Focus on the performance tests of wheel structure the research on FEA method was carried through in order to improve the self-determination design level. Then experiments were used to verify the FEA model. The shortage of the FEA was found. Through limited fatigue life test an applied S-N curve was going to be established based on the real material of wheel through common casting techniques. Analysis of shock response spectrum based on equivalent damnification principle was brought forward. The stress wave and stress spectrum in wheel structure during impact test were gained through frequency spectrum analysis to the test result.