Modeling microfracture evolution in heterogeneous composites: A coupled cohesive phase-field model

Modeling micro-crack evolution in highly heterogeneous solids has been a major challenge in brittle materials owing to their complex microstructures and the complicated interactions between their components. The present work aims to address this challenging task through the development of a novel coupled cohesive phase-field model that can accurately predict the evolution of microfracture and describe interfacial de-bonding in quasi-brittle composites. As a crucial part of our modeling framework, the interface is described by an auxiliary interface variable, thus the interface properties can be regularized. The developed model has the following novelties: (1) the coupled cohesive phase field method is accomplished by implementing a gradient damage formulation to predict crack nucleation and propagation in quasi-brittle solids; (2) the interface properties in complex heterogeneities are regularized by the interaction between matrix and inclusions properties, as well as the width of the interface; and (3) it can precisely predict the crack evolution (crack initiation, propagation, deflection into the matrix) in quasi-brittle heterogeneous solids. Particularly, the proposed model is validated using our implemented experimental results, from which the micro-crack trajectories in fiber-cement composites were observed. The proposed approach shows great potentials in predicting the fiber de-bonding as well as the micro-crack kinking path in complicated quasi-brittle materials.