Oblique Impact Simulation Study of Ti-6Al-4 V Alloy Plates for Analysis of Blade-Off Event in Turbofan Aero-Engine

Aero-engines employ heat-resistant, high-strength alloys such as the titanium-based superalloy Ti-6Al-4 V, in the construction of engine fan blades. Due to several sustained, fatigue and impact loads, these blades are prone to fracture during their operation. In such an event, the kinetically energized fan blade may fly away to impact with the casing or the containment ring of the engine. This could lead to a major catastrophe, if these flying parts manage to penetrate through the engine casing and impact other structural components of the aircraft. In this paper, a simplified analysis of such blade-off event is performed to understand the role of impact velocity, the rotational velocity of the fan blade, blade orientation and the angle of oblique impact of the blade on the engine casing or containment ring. For this, the fan blade and the containment ring are modeled as rectangular plates of appropriate sizes. The problem is analyzed using explicit finite element analysis of the impact of a moving blade on a fixed stationary containment ring at different orientations and velocities of the blade. Standard Johnson–Cook material parameters and fracture criteria have been used to characterize the titanium alloy behavior and failure in impact loading. The results provide useful insights into the impact problem and will help toward improving the design for better safety of the aircraft.