Evaluation of multiple cracks interaction effect subjected to biaxial tension under creep regime

Under creep regime, the multiple cracks would remarkably deteriorate the service life of the component with respect to the case of a single crack due to the higher C* values induced by the interaction and coalescence of the adjacent cracks. In this paper, the creep interaction effect of two identical coplanar surface flaws in a plate subjected to biaxial tension loads were calculated under various crack configurations, creep properties and biaxial stress ratios. The results revealed that the creep interaction level was greatly dependent on crack depth, crack distance, creep exponent and biaxial stress ratio whereas crack shape had little influence. In addition, the creep interaction factor determined by the average C* values along the crack front could better represent the multiple cracks interaction under biaxial stress state. Finally, an empirical equation for the creep interaction factor was established on the basis of the comprehensive finite element analyses and the size of the equivalent single crack replacing the interacted multiple cracks should be determined by the creep interaction factor.