FATIGUE CRACK GROWTH ANALYSIS OF INTERACTING SUBSURFACE CRACKS USING S-VERSION FEM

摘要

Fatigue crack growth simulation using the s-version finite element method (FEM) is presented. Two subsurface cracks are aligned in the depth direction of a specimen, and is subjected to a cyclic tension-tension loading. The fatigue crack growth behavior of the cracks is directly simulated using our automatic fatigue crack growth simulation system with the s-version FEM. Along with the direct simulation, proximity rules for crack combinations and surface cracks are used in the s-version FEM simulation. The numerical results with and without the application of the proximity rules are compared to make a validation of the application of the proximity rules in the evaluation of fatigue crack growth behaviors and residual fatigue life. The results clearly illustrate that the proximity rules accelerate the fatigue crack growth rate, and provide us with a substantially conservative evaluation. Finally, the proximity rules are slightly modified for making better approximation of combining and surface cracks. It can be found that the new proximity rules are able to give a fatigue crack growth evaluation closer to the direct simulation results.