Reliability Analysis Of A Rhombic Vehicle And Anti-Fatigue Optimum Design Based On Virtual Proving Ground

Along with the increasingly competitive auto market, automobile's quality and the reliability performance appear especially important. Anti-fatigue design of automotive structures has become one of the key points in the R&D process of automobiles. In this thesis, to evaluate the anti-fatigue performance of vehicle body, the proving ground reliability test of rhombic vehicle was simulated by using the VPG technique. This study will provide a method to evaluate the anti-fatigue performance of rhombic vehicle before the proving ground durability tests. Then a strategy for anti-fatigue optimal design based on the approximate model, design of experiment and genetic algorithm was posed and was applied to the anti-fatigue optimal design of the aluminum alloy wheel.First, the finite element models of body, tire and suspension system were established. The FE models of tire and the chassis are very important since the load for the body is transmit from them. The virtual tests of tire and leaf spring were conducted, and the mechanical characteristics of components such as leaf springs and busing were thoroughly considered to guarantee the precision and completeness of suspension system model. Then the FE models of the body, tire, suspension system were assembled together to obtain complete FE model of rhombic vehicle, the settle run was carried on to make the vehicle reach a steady state.Next, the FE models of proving ground roads were established, and the virtual durability tests for the rhombic vehicle were simulated by using the explicit finite element code LS-DYNA, then the fatigue life of body was predicted by using the rain flow cycle counting technique and Smith-Watson-Topper algorithm.Finally, take the aluminum alloy wheel as an example, the finite element models of the aluminum alloy wheel and fatigue test machines were built, then dynamic fatigue tests for the aluminum alloy wheel were simulated to predict its durability performance. The anti-fatigue optimal design of the aluminum alloy wheel was conducted based on the approximate model and multi-objective optimization, which improved its anti-fatigue performance while reducing its weight.