Experimental and numerical investigation on low-velocity impact damage and parametric study of composite rotor blades

Modern helicopter rotor blades are made of composite materials. Due to the harsh service environment, the blades may be impacted by hail and other falling objects at low velocity. The damage behavior of composite rotor blades subjected to low-velocity impact is studied here. Low-velocity impact experiment is conducted on a composite helicopter rotor blade, and the impact force and the damage are measured. Based on the experiment, a finite element model is developed and validated to predict the impact damage of the blade. With the model, a parametric study is performed to investigate the effects of impact energy, impact locations, and foam core on impact responses of the composite blades. The results show that the rib is the most vulnerable part to damage, associated with severe deformation, and delamination rapid expanding under low-velocity impact. The foam crush region is close to the blade top surface below the impact point. The interface between the skin and internal part is especially sensitive to increase in impact energy. Impacts near the leading edge produce higher impact force, while impacts near the trailing edge cause large deformation and small impact force. Better impact performance will be achieved when modulus and density of the foam are increased.