A Thermodynamically-Based Phase Field Model for Thermosetting Resins Considering Nonlinear Hardening Effect

The ductile fracture behavior of thermosetting resins is significantly influenced by material viscosity, nonlinear plastic deformation, and plastic hardening characteristics. In this paper, a phase-field model is developed to analyze the ductile fracture behavior of thermosetting resins. The interaction between deformation and damage evolution is captured by coupling the generalized Maxwell–Perzyna constitutive model with the phase-field model, and viscosity-related viscoelastic free energy and hardening-related viscoplastic free energy are incorporated into the crack driving force. The governing equations for deformation and damage evolution are derived within a thermodynamically consistent framework, numerically discretized, and successfully implemented in commercial software. Subsequently, an epoxy resin system was synthesized and validated through homogeneity tests. Uniaxial tensile and compressive tests were conducted at various strain rates to calibrate the model parameters. Moreover, numerical simulations were performed on several representative fracture cases and compared with experimental results. The results show that the proposed model demonstrates excellent capability in accurately predicting critical mechanical characteristics, including stress response, crack propagation path, and rate-dependent ductile fracture behavior of thermosetting resins.