界面凹坑上纵波－瑞利波转换的实验研究

应用超声技术对界面半球形凹坑上的纵波－瑞利波的波型转换进行了实验研究。在一个特制的钢质模型上，频率为ＩＭＨｚ的纵波从６个不同方向依次入射到３个不同直径的表面凹坑上，然后在８个不同的方向上接收瑞利波。所接收的散射信号被数字化后进行了ＦＦＴ运算。根据所得实验数据得知，当纵波垂直入射凹坑时所转换的瑞利波的总能量最大；当凹坑直径与入射波长相等时波型转换率最大等结论。其中一些结果为反卷积运算和已知数值计算所验证。

Experimental Study of Longitudinal to Rayleigh Wave Mode Conversion at a Surface Pit

The longitudinal to Rayleigh wave mode conversion at a hemispherical surface pitis investtwted experimentally by using ultrasonic technique.With a specific steel model,thelongitudinal wave with frequency of 1MHz is projected in sequence at six different incident angleson three surface pits with different diameters and the Rayleigh waves are received in eightdifferent directions on the surface. Then the received signals are digitized and processed withFFT. According to the experimental data,the conclusions are reached that the total convertedRayleigh wave energh is the greated when the longitudinal wave is normally incident and themode conversion rate becomes the largest when the diameter of the pit equals to the wavelength ofthe incident wave,etc.Some of these resultS are identified by deconvolusion and numericalcalculation.