中文摘要：

针对传统线性超声检测无法检测闭合微裂纹的问题，搭建了铝板的微裂纹振动声调制（VAM）检测系统，提取检测信号中的一阶旁瓣非线性信号和只滤除基波的全部非线性信号并对其时域反转，在ABAQUS有限元软件下，将其加载在铝板的无损模型上实现时间反转聚焦，获取铝板模型能量分布云图和各质点的位移信息，以此对微裂纹进行定位。结果表明，在时反信号的聚焦时刻原裂纹位置处有较强能量聚焦，只滤除基波的全部非线性信号聚焦效果优于一阶旁瓣非线性信号，振动声调制技术与时间反转方法结合能够实现对微裂纹的检测和定位。

英文摘要：

Traditional linear ultrasonic testing method is unable to detect the closed micro-crack. Thus, the vibro-acoustic modulation （VAM） detection system is established and used to perform VAM experiments on the first order side-band and whole nonlinear signals are extracted from detection signals on aluminum plate contained micro cracks, and reversed in the time domain. Then, the pre- processed 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 side-band. The combination of VAM and time reversal （TR） method can realize the detection and localization of micro crack.