Experimental and numerical evaluation of fatigue crack growth rate based on critical plastically dissipated energy

A numerical model based on plastically dissipated energy is suitable for predicting crack growth rate in ductile metal under cyclic loading. The critical plastically dissipated energy is a material dependent constant, which are obtained through the inversion by using the numerical model and crack growth experiment of compact tension (CT) specimen. The predictions of this numerical model with crack propagation criterion based on obtained critical plastically dissipated energy are in good agreement with the results of crack propagation experiment of 304 stainless steel CT specimen. The criterion for crack propagation is in accordance with the theory of fatigue cumulative damage of material. By analyzing the influence of constitutive model of material on the accumulation of plastically dissipated energy, it was found that the ideal elastic plastic material has definite threshold load amplitude for crack propagation and the plastic hardening of materials has a great influence on the crack closure effect.