Multi objective optimization of composite laminate repaired by patches in considering static strength and fatigue life

The patch repair is a widely used method for repairing the damaged composite structure, optimizing the repair structure in considering static strength and fatigue life can greatly improve the reliability and safety. However, only static strength and fatigue life are considered during the design or optimization. In this article, the multi-objective optimization of composite laminate repaired by patches in considering static strength and fatigue life was carried out. The models used for predicating static strength and fatigue life were established through finite element method (FEM). Then, the established models were adopted to investigate the effect of repair parameters on static strength and fatigue life, results show that patch radius has the strongest impact on static strength and fatigue life, while the repair thickness and stacking sequence of patch show a greater impact on fatigue life. Based on the above conclusions, Non-dominated Sorting Genetic Algorithm (NSGA-II) was employed to optimize the repair structure. The optimization results show that strength and fatigue life was greatly improved, the repair thickness, and patch volume was greatly reduced, patches that radius is larger than 14 mm can ensure that the repair structure has both higher strength and better fatigue resistance. The proposed optimization method has a good optimization effect for composite laminate repaired by patches.