The optimization thickness of single/double composite patch on the stress intensity factor reduction

The repairing process of structures using bonding of composite materials is an efficient and economic way of increasing service life of damaged structures. The finite element method is developed and applied to assist in the design, assessment and optimization of the proposed plans before they are implemented, therefore reducing cost and time. In this study, the finite element method is used to analyze the behavior of a repaired crack using single and double circular composite patches by determining the stress intensity factor reduction. The effects of geometrical and mechanical properties of the patch on the fracture parameters are highlighted. The results show that the thickness gain and the reduction of the asymptotic value of the SIF in the case of the double patch is 7% when compared to the single one. Thus, the gain in the thickness decreases when the thickness of the bonded patch increases up to a value eP = 0.8 mm and beyond this value, it starts increasing. However, an inverse behavior occurs for the mixed mode. In addition, whatever is the size of the strengthened crack, the gain in thickness exceeds 16% in mode I and 20% in mixed mode.