Abstract <p>A new framework combining a thermodynamically consistent mixed-mode phase-field model and a physically consistent mixed-mode cohesive zone model is proposed to simulate mixed-mode fracture of polymer composites at the microscale. This framework more accurately captures damage mechanisms and crack evolution in the matrix and the interfacial regions than previous models. It is implemented in commercial software Abaqus 6.14 via a user element (UEL) subroutine. To address the non-physical behavior in the existing cohesive response within the Abaqus interface, a simplified approach, namely, the damage activation function method in the mixed-mode framework, is considered. A zero-thickness cohesive element algorithm based on a cKDTree data structure from Python’s Scipy module is developed to generate zero-thickness elements along arbitrarily shaped curved interfaces. Numerical examples, including two benchmark cases, demonstrate the robustness of the proposed approach. A detailed investigation of a mixed-mode fracture example is conducted, with energy dissipation and work potential plotted against numerically measured crack length.</p> Graphical abstract <p></p>