In the acousto-ultrasonic technique, it is essential for successful application of the technique to understand the propagation characteristics of ultrasonic wave. An FEM method was used to investigate the acousto-ultrasonic wave propagation. The simulating signal was processed by 2-DFFT to recognize the modes and compare with the theoretical parameter curve of the frequency versus wave number spectrum. It had been found that the dominant acousto-ultrasonic wave produced were multimode lamb waves. In order to show the acousto-ultrasonic wave propagation, the results were presented in from of snapshots. It was approved that combine the numerical analysis with experiment was an efficiency way in the ultrasonic testing.%在声一超声检测中,正确认识超声波传播特性是其被有效应用的基础.通过有限元数值模拟的方法,研究薄板中声-超声检测形式下超声波传播模式,对模拟产生的波形信号用二维傅里叶变换法进行模式识别,并与兰姆波的理论波数频散曲线进行对比,证实产生了多模式兰姆波.使用波场快照图观测了声-超声检测方式下超声波的传播特性.研究表明,将数值模拟方法和试验相结合是研究超声检测技术的有效途径.
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