Local defect internal resonance method for ultrasonic damage identification of adhesive interface debonding

The bonding interface is prone to debonding under environmental implications and long-term operational vibrations, which may severely affect the structural integrity. In this paper, considering the complex intermodal dynamic characteristics caused by interface debonding, a local defect internal resonance method is proposed for the first time to solve ultrasonic damage identification for adhesive interface debonding. Firstly, based on a two degree of freedom (2-DOF) nonlinear model of local defects in the bonding interface, the multi-scale method is used to explain the mechanism of the internal resonance of local defects and the conditions for the generation of the internal resonance. By analyzing the saturation phenomenon peculiar to the 2:1 internal resonance of local defects in the spectrum, the adhesive interface debonding identification experiment of a bonding aluminum plate is carried out. The effectiveness of the local defect internal resonance method is verified by theoretical analysis and experimental results. The experimental results show that the debonding damage produced a V-shaped combination of excitation amplitude and frequency which can produce internal resonance characteristics. Further, the local defect internal resonance method is found to be effective in solving adhesive interface debonding detection.