Fatigue crack growth assessment by FEA-based simulation of damage accumulation

Abstract

Abstract. Fatigue crack extensions are typically predicted by application of the Linear fracture mechanics techniques. However, there is a problem of numerical estimations of the crack three-dimensional shape and front extension, which becomes insoluble when the crack approaches the back face of the analyzed detail. Also, considering material plasticity, especially at the stage preceding the through thickness crack extension or complete fracture of a detail, is beyond the scope of the technique. An approach based on the FEA simulation of fatigue damage accumulation has been developed. It allows assessing the crack initiation and propagation until complete failure of the detail affected. The approach is illustrated considering the example of fatigue failure of the non-continuous fillet-welded joint with incomplete penetration of weld material. The crack initiation in the cavity, its three-dimensional shape formation and evolution are simulated taking into account the elastic-plastic cyclic deformation of weld material until almost complete failure of the joint. The results of the analysis are in good agreement with the published experimental data.