非均匀介质体中的缺陷响应研究

Defect response in inhomogeneous materia

由于粗颗粒界面的散射作用,所以在考虑了超声波在非均匀介质体中传播时的衰减以及相速度的频散特性的基础上,用MGB模型表示了入射超声波波束,对非均匀介质固体中的缺陷响应进行了研究。分析了不同尺寸的方形孔缺陷由于压电超声传感器距离其位置的不同对接收到回波信号的影响,同时研究了由于粗颗粒平均尺寸的变化对接收回波信号的影响;并给出了不同颗粒直径尺寸的变化对回波信号影响的实验研究结果。研究结果表明:Born近似方法对弱散射体的散射作用下的预测效果较好,但在强散射体作用下不能使用这种方法预测;实验的结果和理论的预测结果基本一致。

On the basis of ultrasonic attenuation and phase velocity dispersion due to grain scattering, Multi-Gaussian Beam (MGB) model is used to represent the incident ultrasonic beam. Defect response is studied in inhomogeneous material. The variation of received voltage is analyzed against the distance of the defect from the transducer for different dimensions of a square cylinder void. The effect of variation of mean diameter of the grains on the received voltage for different domain of interest is also studied. At the same time, the experimental result is also given about different mean diameter of the grains on the received voltage. The result shows that Born approximation has a good predictability in the scattering of the weak scatterer, but the method is not suitable to the strong scattering particles. The experimental results are basically in accordance with theoretical predictions.