An interface-width-insensitive cohesive phase-field model for fracture evolution in heterogeneous materials

Abstract

In heterogeneous materials, such as fiber-reinforced composites, composite laminates, and coating systems, failure depends on the fracture behavior of the component materials and their interfaces. Modeling crack evolution in heterogeneous materials has been a significant challenge due to the complex interactions between the cracking at the interface and within the material. This paper proposes a cohesive phase-field model based on diffused interface to deal with failure at interfaces. The effective interfacial fracture toughness is obtained based on the fracture toughness of the diffused interface being equivalent to a sharp representation. The effective interfacial fracture strength is approximated using the brittle fracture condition. Then, we propose an approach to minimize the modification of the interfacial fracture parameters. The novelties of this approach are that 1) it is flexible enough to handle brittle and cohesive failure in the interface and bulk; 2) it can capture the crack nucleation at weakly singular interfaces in heterogeneous materials; and 3) compared with other approaches, the calculated fracture behavior is insensitive to the width of the diffused interface. The approach is verified under cases of brittle and cohesive failure. In addition, we demonstrate the approach in describing the fracture behavior of fiber-reinforced composites and ceramic coating systems, finding it to conform exactly with theoretical and experimental results. Hence, the proposed approach shows great potential in predicting crack evolution in heterogeneous materials.