Abstract

In this paper, Comprehensive progressive damage analyses are performed to evaluate the effects of patch sizes and layups on re-starting crack growth of single-side repaired panels with central inclined cracks under high cycle fatigue loading. Complicated nonlinear damage behavior of adhesive bonding, composite patch, mixed-mode cracks and fatigue loadings require precise numerical tools to consider and analyze the coupling effects of various damages on fatigue life of such complex component. For this purpose, two user-written materials subroutines added to a commercial finite element software to capture adhesive debonding and composite patch damages under high cycle fatigue. In progressive damage analysis, high cycle fatigue cohesive zone modeling used for debonding of patch and high cycle fatigue continuum damage model used for composite patches. Practical composite patch layups and sizes are selected in huge number of models and the restarting crack growth life are predicted. The results shown that the composite plies angles attached to the cracked panels have dominant effect on restarting crack growth life. Different combinations of the same layup angles show completely different restarting crack growth lives. The obtained results show the possibility of increasing the restarting crack growth life using an appropriate composite patch layup and geometry dimensions.