Fatigue Crack Growth Life Prediction for Surface Crack Located in Stress Concentration Part Based on the Three-Dimensional Finite Element Method

Abstract

Fatigue crack growth prediction methods using three-dimensional finite element analyses were investigated to improve the predictability of part-through surface crack growth life. First, a direct analysis method of cyclic finite element analysis was adopted. Fatigue crack growth was predicted on a step by step basis from the Paris’ law using stress intensity factor range (ΔK) calculated by the three-dimensional finite element method. This method takes the procedure of cyclic operation of finite element analysis modeled with crack tip elements, crack growth increment calculation and remeshing of the finite element model. Second, a method based on the influence function method for the ΔK calculation directly using three-dimensional finite element method analysis result has been developed and applied. It was found that crack growth prediction based on the step by step finite element method and the method based on the influence function method showed good correlation with the experimental results if Paris’ law coefficient C, determined by CT specimen, was appropriately used for a semi-elliptical surface crack.