Experimental and numerical investigation on fatigue failure of composite helicopter main rotor hub

Abstract: The Main Rotor Hub is a very critical component of the helicopter considering that its failure may determine catastrophic consequences for the whole rotorcraft. A complete experimental and numerical analysis is so necessary to certificate the fail safe and eventually the damage tolerant behavior of the component. In this paper the fail safe behavior of a composite titanium-graphite Rotor Hub is analyzed. The component, with artificial technological defects, was tested with complex contingent fatigue load in order to cause the failure of the titanium section. The failure started in proximity of a high stressed area and it propagated quickly in the whole titanium section but without involve the surrounding filament winding graphite, that is a fail safe device. The behavior of the hub during the whole test is simulated, with good accuracy, by means of a complete FE model that reproduces also the 3D propagation of the crack in the titanium section.