Prediction of fatigue crack growth using finite element analysis techniques applied to three-dimensional elastomeric components

Elastomer components fail at cyclic strain amplitudes much lower than their catastrophic tear strength as a result of cumulative cyclic fatigue crack growth. Cracks typically develop in regions of high stress concentrations. In general, the rate of growth is determined by them shape of the component, and the nature and magnitude of the deformation imposed. Extensive earlier work has been done on the prediction of fatigue life of components. However, the reproducibility of the results was poor and, in addition, there was a low degree of accuracy. A fracture mechanics approach, which uses finite element analysis techniques to calculate strain energy release rates for cracks located in three-dimensional components, was used in combination with experimental measurements of cyclic crack growth rates of specific strain energy release rate to predict the cyclic crack growth propagation rate and the eventual fatigue failure of an elastomeric engineering component in three modes of deformation, namely: tension, simple shear and combined shear and tensile (450 angle) deformations. The fatigue crack growth for the gearbox mount under investigation was predicted within a factor of 2 at different displacements for all three modes of deformation.