A Phase-field Ductile Fracture Model for Polymers Considering Asymmetrfy Hardening Characteristic

Ductile fracture in polymeric materials involves complex plasticity-damage coupling, with tension-compression asymmetry significantly influencing damage evolution. Existing phase-field models inadequately account for plastic hardening asymmetry, limiting predictions for polymers exhibiting substantial plastic deformation. This study develops a novel phase-field model incorporating an improved plastic free energy formulation to capture hardening asymmetry within a thermodynamically consistent framework. Four 2D and 3D fracture problems were analyzed to evaluate the proposed model’s performance. Numerical predictions demonstrated good agreement with experimental data from the literature for load-displacement curves, crack initiation, and propagation paths, with maximum RMSE below 10%. Moreover, the proposed model exhibited superior prediction accuracy and computational efficiency compared with phase-field models neglecting plastic hardening asymmetry, particularly for material stiffness degradation rate, damage initiation location, and crack path evolution.