Numerical Verification of Three-Dimensional Elastoplastic Crack-Tip Fields and Constraint Parameters Utilizing Ansys Mechanical

Abstract

This study presents a computational verification of three-dimensional (3D) elastic-plastic crack-tip fields, emphasizing the dual-parameter fracture mechanics framework (J–Q) through finite element analysis (FEA) in Ansys Mechanical. While single-parameter fracture mechanics (K or J dominance) adequately describes high-constraint, plane-strain conditions, it fails under low-constraint or varying thickness scenarios. High-fidelity 3D Compact Tension (CT) models were analyzed across normalized crack lengths (a/W = 0.35–0.55) and specimen thicknesses (B = 12.5–50 mm). Numerical J-integral values were validated against ASTM E1820 analytical equations, achieving <1.6% error with optimized spiderweb mesh refinement. The J–Q framework quantified constraint loss, revealing transitions from out-of-plane plastic relaxation (Q = –0.38) in thin geometries to high-triaxiality plane strain states (Q = 0.15) in thick specimens. These findings establish a robust computational blueprint for nonlinear structural integrity assessments.