金属基复合材料结构深层脱黏缺陷超声检测中检测频率的选取

Frequency Selection in MMCS Default Detecting Based on Ultrasonic Method

从平面波在多层介质中的反射和透射规律出发,研究了超声波在金属基复合材料结构中的传播特性,根据波动方程,推导出金属基复合材料结构深层脱黏缺陷检测时最佳的超声波频率。实验结果表明,在检测频率选取适当的情况下,超声波在金属基体中发生全透射,可以到达深层界面,保证回波信号中包含深层界面的缺陷信息。

Presented an effective approach for selecting ultrasonic frequency in detecting debond default of Metal Matrix Composite Structure （MMCS）. With the aid of theory on wave propagation, a theoretical study is presented on propagation characteristics of plane wave when it passes through MMCS, calculation methods are presented for the reflection and transmission spectnnn of the ultrasonic waves incident from the fluid onto the general anisotropic solid layer. It is found that the sound reflection and. transmission coefficients depend on the media parameters, orientation and thickness of the solid layer, incident angle and sound wave frequency. The results show that the ultrasonic wave can totally penetrate through metal layer if the detecting frequency is proper, then the deep layer debond information could be extract from the ultrasonic echo signal.