An Improved Methodology based on Continuum Damage Mechanics and Stress Triaxiality to Capture the Constraint Effect during Fatigue Crack Propagation

Abstract An improved continuum damage mechanics (CDM) and extended finite element method (XFEM) methodology is proposed to consider the effect of crack tip constraints on the fatigue crack growth (FCG) behavior. Several FCG experiments are conducted on compact tension (CT), single edge notch bending (SENB) and middle tension (MT) specimens prepared from modified 9Cr-1Mo steel. Combined CDM-XFEM methodology is improved to capture the crack tip constraints effect. Experimental and simulated FCG lives are compared to each other and found in good agreement. This analysis shows that the triaxiality parameter is a key parameter for estimating the crack tip constraints correctly.