Computational Modeling of Fatigue Crack Path Evolution in Ti-6Al-4V under Cyclic Loading

This study presents a detailed numerical investigation of fatigue crack propagation in linear elastic materials subjected to mixed-mode (Mode I + Mode II) loading, with particular emphasis on the role of geometric discontinuities in Modified Compact Tension Specimens (MCTS). Finite Element (FE) analysis using ANSYS is employed to simulate mixed-mode fatigue crack growth in four Ti-6Al-4V specimen configurations (MCTS01–04), each characterized by different hole locations and spacing. Within the framework of Linear Elastic Fracture Mechanics (LEFM), Paris’ law is adopted to quantify fatigue crack growth behavior and establish crack length–cycle relationships for the considered configurations.

The computational methodology integrates incremental crack growth under cyclic loading, fatigue life prediction based on crack propagation rates, and precise evaluation of mixed-mode Stress Intensity Factors (SIFs). Crack path trajectories are determined using energy release rate criteria in conjunction with local stress field analysis. Simulations are performed under constant amplitude loading conditions to accurately predict crack propagation paths and corresponding fatigue life.

A systematic parametric study is conducted to assess the influence of hole placement and spacing on stress concentration, crack deflection, and crack growth rates. The results reveal significant sensitivity of crack trajectories and fatigue life to geometric variations. These findings provide critical insights for the design and optimization of damage-tolerant structures, demonstrating the effectiveness of advanced fracture mechanics-based numerical modeling in predicting fatigue behavior.