Crack renucleation in bioinspired discontinuous interfaces under thermo-mechanical loading

Thermo-mechanical coupling can significantly affect the mechanical behavior of composites and may lead to unstable crack propagation at interfaces. Composites contain both continuous and discontinuous interfaces, and discontinuous interfaces can lead to crack renucleation and affect the overall toughness of the material. To explore the effect of discontinuous interface fracture on crack driving force under temperature conditions, a coupled thermo-mechanical phase field fracture model with temperature-dependent elasticity and fracture properties is developed and combined with the interface model. In the continuous interface fracture model, the greater the difference in the thermal expansion coefficient of the material components, the more significant the effect of temperature on the interface fracture. In the discontinuous interface fracture model, the crack-bridging toughening mechanism exhibits anisotropy. This anisotropy is exacerbated by the destruction of mineral bridges. The local energy dissipation is further considered and possible porous structures are designed to capture the corresponding toughening mechanisms. Inspired by the intermittent crack propagation caused by the nano- porous micropillar interface at the tail of the lizard, the toughness asymmetry of the discontinuous interface is proved by 3D printed bioinspired structure specimens, and the effect of crack renucleation on the toughening of the discontinuous interface structure under thermo-mechanical loading is discussed. These results reveal the thermal fracture mechanism and the corresponding toughening mechanism of the discontinuous interface and provide a reliable reference for developing new engineering materials.