Multi-scale modeling of pultruded glass fiber-reinforced polymer composites incorporating the phase-field method

This study develops a multi-scale finite element model incorporating the phase-field method (PFM) to predict the mechanical response and failure behavior of pultruded glass fiber-reinforced polymer composites with unidirectional (UD) and woven fabrics. The model evaluates tensile behavior under loads applied at various orientations. At the microscale, a representative volume element was constructed to determine the effective elastic properties and failure parameters of the composite. To capture transverse and out-of-plane shear strength of UD plies, PFM was combined with cohesive elements, enabling simulation of both matrix cracking and interfacial debonding. At the macroscale, the framework integrates PFM for matrix failure with the 3D Hashin damage criterion for fiber failure. Numerical predictions were validated against experimental tensile tests performed at 0°, 10° and 90° to the fiber direction in the UD layer, accurately reproducing localized necking in UD plies at 0°, shear-driven diagonal cracking at 10°, and nonlinear responses from debonding at 90°. Owing to its high accuracy, low computational cost, and calibration-free nature achieved through the explicit representation of constituent components, the proposed model provides an efficient approach to optimizing composite structures for targeted mechanical performance.