Simulation and testing of a non-linear ultrasonic system for testing the debonding of the adhesive layers of magnesium alloys

Abstract

The debonding of adhesive layers caused by reduced mechanical binding force and adsorption is expected to influence the overall performance of materials or structures, on which this non-linear ultrasonic non-destructive testing method was used. Meanwhile, a non-linear ultrasonic system for testing the debonding of the adhesive layers was established to test specimens thereof on magnesium alloys with different degrees of debonding. By doing so, the amplitudes of the fundamental and second harmonics were measured and the ultrasonic non-linearity parameter calculated. The experimental results demonstrated that the ultrasonic non-linearity parameter was sensitive to the debonding of the adhesive layers of the magnesium alloys, and exhibited a quadratic relationship with the degree of debonding as the latter increases. Besides, a finite element simulation model was established to perform numerical simulation of the specimens of the adhesive layers of magnesium alloys which had debonded to different degrees. The simulation results were basically coincident with the experimental results, which further demonstrated that the proposed non-linear ultrasonic testing technology is applicable to the non-destructive evaluation of the debonding of the adhesive layers.