A study on the determination of closing level for finite element analysis of fatigue crack closure

An elastic-plastic finite element analysis is performed to investigate deta iled closure behavior of fatigue cracks and the numerical results are compa red with experimental results. The finite element analysis performed under plane stress using 4-node isoparametric elements can predict fatigue crack closure behavior. The mesh of constant element size along crack surface can not predict the opening level of fatigue crack. The crack opening level fo r the constant mesh size increases linearly from initial crack growth. The crack opening level for variable mesh size, is almost flat after crack tip has passed the monotonic plastic zone. The prediction of crack opening leve l using the variable mesh size proportioning the reversed plastic zone size with the opening stress intensity factors presents a good agreement with t he experimental data regardless of stress ratios.