Modeling arbitrarily oriented and reorienting multiscale cracks in composite materials with adaptive multiscale discrete damage theory

An adaptive multiscale modeling approach based on the multiscale discrete damage theory (MDDT) is established to describe formation of arbitrarily oriented and progressively reorienting cracks at multiple scales in heterogenous materials. MDDT tracks the fracture process over a set of discrete cohesive failure surfaces in the microstructure and consistently bridges the microscopic cracks to the continuum representation of damage at macroscale based on the reduced-order homogenization method. In this manuscript, the adaptation to arbitrary orientation of a crack is achieved using the idea of effective rotation of microstructure which reorients the prescribed failure path at the direction of crack propagation. The MDDT model representing the microstructure is analytically transformed given a crack nucleation orientation and an identification criterion. The performance of the proposed model is demonstrated at the microscale under multiaxial loading conditions. The predictive capabilities of the model are validated using four-point bending test of concrete beam and delamination migration experiments of fiber-reinforced composite cross-ply laminates. The qualitative and quantitative evaluations of crack propagation and reorientation show good agreement with the experimental results.