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Automotive shock absorber shims are subjected to deformation while generating the pressure differential across the rebound and compression chambers. Considering the contact, large deflection, and material this shim stack deformation will be nonlinear throughout the working velocity of shock absorbers. The deformation of shim stack mainly depends on number and geometry of deflection disk, number and geometry of ports, and clamping disk geometry on which shims are rested. During the rebound and compression stroke of the shock absorber, the oil flows through the piston and base valve ports. High pressure oil developed during mid and high velocity of shock absorber results in deflection of shim stack in piston and base valve assembly. This deflection leads to oil leakage through the shim stack which results in change in damping force by the shock absorber.

In an automotive twin tube shock absorber, thin structures used in piston and base valve sub-assembly are called shims. These shims are used in proper combination to achieve particular damping force characteristics and these shims will be operating continuously throughout the life of shock absorber. Any failure of shims during lab/ vehicle testing will increase the development time and cost considerably. Hence, predicting the operating life of shim assembly is very important during shock absorber development stage. In order to predict the life of the shim assembly, simulation techniques can be applied with fair degree of accuracy. Currently, during structural simulation of shim assembly, it is assumed that fluid pressure is acting uniformly over the entire shim to find stress intensity. This approximation is taken into account to predict the fatigue life of shim assembly. This paper proposes additional technique to carry out close to real life shim simulation.