Fracture behavior of Ti-6Al-4V in the extreme thermo-mechanical environment of fan blade-out.

This study presents a comprehensive numerical analysis of stress triaxiality and damage evolution in Ti-6Al-4V aeroengine containment case under realistic Fan Blade-Out (FBO) loading conditions. Using a finite element model with a validated Johnson-Cook (JC) damage model, we investigate the fan case’s response across a range of rotational speeds, culminating in an extreme-speed fracture event. The simulations accurately capture the complex interplay of high strain rates (~ 104 s−1), significant adiabatic heating (> 900 °C), and evolving stress states. A key finding is a speed-dependent shift in the failure mechanism, from tensile-driven damage at lower speeds to shear-dominated failure at higher speeds. The fracture analysis of failure predicted under coupled, high-temperature, high-strain-rate conditions shows the model operating in a slight extrapolated regime. This highlights considerable uncertainty in using models calibrated with standard, decoupled tests for predicting failure in complex, termo-mechanical events. The findings underscore the necessity of new experimental data for FBO analysis that captures coupled thermo-mechanical effects to improve the predictive accuracy of computational fracture mechanics and ensure the robust design of damage-tolerant aeroengine components.