基于超声无损检测技术的需要, 该文在理论分析声表面波混频效应的基础上, 提出了一种混频声表面波的激发方法, 并进行了相应的声表面波混频谐波的实验观察研究。设计并制作了以斜入射的体横波和体纵波分别激发声表面波的楔块, 通过选择适当的体横、纵波激励信号的周波数及时间延迟, 可使斜入射体横、纵波分别激发的声表面波完全混叠。通过对接收到的混叠声表面波时域信号进行脉冲反相处理和傅里叶变换, 得到明显的声表面波混频谐波信号。结果表明, 借助于楔块两列斜入射的体横、纵波可有效产生混频声表面波, 实验观察与理论预期一致, 这为发展基于混频声表面波的超声无损检测技术奠定了基础。

Based on the needs of ultrasonic nondestructive testing technology, a method for exciting the frequency-mixing surface acoustic waves based on the theoretical analysis of the frequency-mixing effects of surface acoustics waves is proposed in this paper, and the corresponding experimental observation of frequency-mixing harmonic of surface acoustic waves is carried out. A wedge transducer consisting of a transverse transducer and a longitudinal one is designed and fabricated to excite the mixing surface acoustic waves induced by the oblique incidence of a bulk transverse wave and a bulk longitudinal one. By choosing appropriate cycle number and time delay of the transverse and longitudinal wave excitation signals, the surface acoustic waves excited by the oblique incident bulk transverse and longitudinal waves can be completely mixed. By performing pulse inversion processing and Fourier transform on the received time-domain signals, the apparent surface acoustic wave mixing harmonic signals can be obtained. The results show that the mixed-frequency surface waves can be effectively generated with the help of the oblique incident transverse and longitudinal waves passing through the wedge, and the experimental observation is consistent with the theoretical expectation, which lays a foundation for the development of ultrasonic non-destructive testing technique based on the mixing surface acoustic waves.