Experimental and Numerical Investigation of Patch Repair for Composite Laminates Subjected to Low-Velocity Impact

The widespread use of composite materials has led to an increased focus on restoring the mechanical properties of damaged composite structures to ensure system safety. This study combines compression experiments and finite element simulations to investigate the effectiveness of different patch sizes and repair methods, including single- and double-sided repairs, in restoring the structural strength of composite laminates with barely visible impact damage (BVID). The results demonstrate that low-velocity impact significantly affects the strength of the laminate, reducing it to 68.53% of its original strength, highlighting the necessity of patch repair. For composite specimens repaired using patching, an increase in the patch radius consistently enhances strength recovery, reaching up to 93.96% of the original strength. However, this also leads to an increase in weight, suggesting that the patch radius should be selected based on the specific requirements of the application. Furthermore, double-sided patching is preferable to single-sided patching. This approach improves the repair efficiency by 4.96%, primarily due to its ability to provide a more uniform stress distribution. Consequently, the risk of premature buckling and failure under compressive loading is significantly reduced, ensuring improved structural integrity and durability. The finite element simulation results presented in this study align well with the experimental findings, with a maximum error of no more than 10.68%. In conclusion, this work provides reliable guidance for the optimal patch repair of composite structures and lays a solid foundation for the practical application of patch repairs in engineering.