Toughening by interfacial self-healing processes in bioinspired staggered heterostructures

Dynamic breaking and reforming of sacrificial bonds in sliding interfaces of biological and bioinspired heterostructures could greatly enhance fracture resistance by providing a self-healing energy dissipation process. Nevertheless, how interfacial self-healing behaviors and nonuniform stress transfer act in concert over multiple length scales and boost fracture toughness remains elusive. Here, a multiscale fracture mechanics model for bioinspired staggered heterostructures was developed by integrating interfacial self-healing behaviors, RVE's deformation responses, and macroscopic crack bridging. We found two critical brick sizes between which the fracture toughness enhanced by interfacial self-healing processes surpasses that by ideal elastic-plastic interface. The simultaneous increased crack-bridging stress and opening displacement induced by interfacial nonuniform deformation modes, including elastic, strengthening and sliding stages between the two critical sizes, are identified to enhance the fracture resistance. Moreover, our model provides parametric guidelines for optimizing bioinspired fracture-resistant structural materials with self-healing interfaces.