Fatigue crack-growth life prediction of Ti-6Al-4V components using finite-element analysis and Kriging surrogate modeling

Landing-gear components are subjected to repeated impact, taxiing, braking, and ground-maneuver loads, making reliable crack-growth assessment essential for safe operation. This study develops an experiment-informed computational framework for predicting the crack-propagation life of Ti-6Al-4V components. Compact-tension tests conducted in accordance with ASTM E647-24 were used to determine the Paris-law parameters and characterize the fracture-surface morphology. A three-dimensional crack-growth model incorporating local crack-tip refinement and an equivalent surface residual-stress field was validated against measured crack-length histories. The finite-element model achieved an overall RMSE of 0.779 mm, MAE of 0.576 mm, R ² of 0.965, and MAPE of 1.93%. One hundred Latin hypercube samples were then used to train a Kriging surrogate that maps seven inputs—the Paris constants, load ratio, maximum load, residual stress, initial crack length, and crack extension—to the scalar accumulated cycle count. Within the stable crack-growth regime, the surrogate yielded an RMSE of 1.30 × 10 ⁴ cycles, MAE of 1.10 × 10 ⁴ cycles, R ² of 0.969, and MAPE of 8.75%. Sensitivity analysis identified the initial crack length, applied load, and stress ratio as the dominant variables, with normalized contributions of 55.4%, 35.7%, and 8.9%, respectively. The framework enables rapid, uncertainty-aware screening of crack-growth life under loading conditions relevant to aircraft landing gear.