Modeling the interaction between intra and interlaminar cracking in FRP composites using phase-field regularized interface fracture

Document Type


Publication Date



Department of Mechanical Engineering-Engineering Mechanics


Fiber-reinforced polymer composites (FRPCs) exhibit a complex range of failure mechanisms, including matrix cracking, fiber breakage, fiber–matrix debonding, and delamination. Among these failure modes, interlaminar fracture or delamination across the interfaces between the different layers (plies) is commonly observed in experiments. Hence, the fracture behavior of these interfaces plays a critical role in determining the overall fracture performance of the FRPCs. In this work, our aim is to model the effect of interface on the final failure of FRPC laminates. Specifically, the present work focuses on modeling the complex interactions between the bulk FRPC damage and interfacial delamination in the carbon fiber reinforced composites (CFRP) within the realm of phase-field fracture. In the present formulation, the phase fields smear the sharp interface between FRP plies as regularized cohesive zones and also describe the bulk crack surface density eventually allowing interaction between bulk damage and interfacial delamination. For the composite's constitutive description, the FRPC is treated as a homogenized material, with effective mechanical properties depending on the properties of the individual matrix and fibers with their respective volume fractions. The elastic matrix is assumed to be isotropic, while the fibers are characterized by their orientations. Further, an anisotropic modification is considered in the fracture energy of the FRPC to promote crack growth along the fiber direction. The model is implemented in a commercial finite element package and several numerical examples are presented to illustrate the complex crack path behavior in CFRP. Specifically, crack growth and interactions are simulated when there is a mismatch in the fiber orientation between the adjacent plies, resulting in dissimilar material properties on either side of the interface. The utilization of the regularized interface phase field model in an anisotropic framework to account for the mismatch in fiber orientation and hence material properties between the laminas makes it capable of predicting complex modes of fracture in FRPC laminates as demonstrated in the numerical simulations. We have also compared the model predictions with the experiments to validate their accuracy.

Publication Title

Theoretical and Applied Fracture Mechanics