Fatigue strength predictions of FOD dents using ΔK threshold methods considering residual stresses

Abstract

Fatigue strength predictions of TC4 FOD-dent specimens using ΔK threshold methods considering residual stresses were the main emphasis in this paper. Both the experimental simulation and the fatigue test were conducted to evaluate the HCF performance of the real FOD dent. The geometrical models of FOD dents were established for the elastic stress concentration analysis. Residual stresses around the dent were numerical simulated or reservedly solved from the laboratory test data and subsequently established as a function of the dent depth. With numerical simulated residual stresses, the prediction results fall into an error interval of about ±30 %. With the reserved residual stress, the method has a smaller error interval of about ±20 %. Both the two procedures can fortunately meet the exit criteria which is probably because the potential micro-damages like micro crack and adiabatic shear band etc. could be counted as sharp cracks.