Interface toughening effect of bio-inspired suture structure on fiber metal laminates

Enhancing the fracture toughness of the metal–resin interface is essential for improving the overall performance of fiber metal laminates (FMLs). This study is the first to propose to utilize the characteristics of the metal-resin interface as a weak interface and construct a bio-inspired suture structure at the interface to improve the interface fracture toughness. Experimental results demonstrate that the bio-inspired suture structure forms a mechanical interlock at the interface, dissipates more energy under loading, and impedes crack propagation. In test specimens, the critical strain energy release rate ( G IC ) reached 4.05 kJ/m 2 when the suture’s minor axis length is 3.0 mm and the offset angle is 25°. Therefore, the construction of bio-inspired suture structure at the interface proposed in this study has great application potential for FMLs, which provides a new idea for improving the fracture toughness of metal-polymer interface.