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The dynamic behavior of the fuel inside a fuel tank and the fuel pressure caused by the acceleration of the vehicle during a rear crash will determine whether a damage of vehicle fuel system resulting in fuel leakage will occur. The dynamic behavior of the liquid and the gas in the fuel tank depends on the fuel tank capacity, shape, and the level which the fuel tank is filled. The mode and severity of the crash will also affect the pressure distribution inside the tank. In order to predict fuel system leakage in early stage of vehicle design before any test vehicles are made, it is necessary for the crash analyst to have a tool that can predict this phenomena. The analyst should have the capabilities to compute not only the fuel tank pressure, but also possible fuel system pipe cut during the crash.

This paper describes the application of the MSC/NASTRAN finite element program to the structural analysis of automotive vehicle wheels and the optimization of wheel designs subject to both NVH and fatigue related constraints. Common wheel design considerations are discussed including wheel tests for both fatigue and stiffness. Techniques for the finite element modelling of wheels subjected to such loadings are described including MSC/NASTRAN cyclic symmetry capabilities, solid element modelling and plate element modelling of wheels. The use of OPUS (Optimization Process Utility System) interfaced with MSC/NASTRAN for automated design optimization is described. Its application to the structural optimization of a cast aluminum wheel using gage related design variables and both NVH and fatigue related constraints is described. It is concluded that such analytical techniques represent a practical approach to the design, structural analysis, and optimization of automotive vehicle wheels.