Abstract:Traditional linear ultrasonic testing method is unable to detect the closed microcrack. Thus, the vibroacoustic modulation(VAM) detection system is established and used to perform VAM experiments on the first order sideband and whole nonlinear signals are extracted from detection signals on aluminum plate contained micro cracks, and reversed in the time domain. Then, the preprocessed signals are loaded into a finite element model built by ABAQUS. The cloud image and particle displacement are obtained and can provide the location information of micro cracks. The simulated results show that there is a stronger energy focusing around the original crack location at focusing time of the reversal signals. The whole nonlinear signals has better focusing performance than the signal only contain first order sideband. The combination of VAM and time reversal (TR) method can realize the detection and localization of micro crack.