Parameters sensitivity and optimization for composite scarf repair

Scarf repair is the preferred method to restore the load-carrying capacity of the damaged structure of fiber-reinforced composite material when stiffness, strength, and flushness are needed. However, shear stress concentration occurs along the scarf bond line coinciding with the location of 0° plies. Previous studies did not consider the sensitivity of parameters systematically and involve the interaction effect. In this paper, sensitivities of scarf angle, adhesive thickness, and stacking sequence are evaluated synthetically through main effect and interaction effect by using the method of design of experiment. The general strategy of decreasing scarf angle needs to remove more materials from parent laminate. Thus, a new strategy of changing the stacking sequence of repair is performed to reduce the adhesive stress concentration by means of the optimization based on genetic algorithm. In spite of this, optimization results may not have good reliability especially when manufacture, load, and other fluctuations happen. Robustness analysis based on Monte Carlo simulation is used to estimate the reliability of optimization results.