模式转换漫散射超声背向散射。

Mode-converted diffuse ultrasonic backscatter.

机构信息

Mechanical and Materials Engineering, W342 Nebraska Hall, University of Nebraska-Lincoln, Lincoln, Nebraska 68588-0526, USA.

出版信息

J Acoust Soc Am. 2013 Aug;134(2):982-90. doi: 10.1121/1.4812769.

DOI:10.1121/1.4812769

PMID:23927097

Abstract

Diffuse ultrasonic backscatter describes the scattering of elastic waves from interfaces within heterogeneous materials. Previously, theoretical models have been developed for the diffuse backscatter of longitudinal-to-longitudinal (L-L) wave scattering within polycrystalline materials. Following a similar formalism, a mode-conversion scattering model is presented here to quantify the component of an incident longitudinal wave that scatters and is converted to a transverse (shear) wave within a polycrystalline sample. The model is then used to fit experimental measurements associated with a pitch-catch transducer configuration performed using a sample of 1040 steel. From these measurements, an average material correlation length is determined. This value is found to be in agreement with results from L-L scattering measurements and is on the order of the grain size as determined from optical micrographs. Mode-converted ultrasonic backscatter is influenced much less by the front-wall reflection than an L-L measurement and it provides additional microstructural information that is not accessible in any other manner.

摘要

漫散射超声背向散射描述了各向异性材料内部弹性波从界面的散射。先前，已经为多晶材料中纵波-纵波（L-L）散射的漫散射开发了理论模型。采用类似的形式，本文提出了一种模式转换散射模型，以量化入射纵波中散射并转换为多晶样品中横波（剪切波）的分量。然后使用该模型拟合与使用 1040 钢样品进行的声发射换能器配置相关的实验测量。通过这些测量确定了平均材料相关长度。该值与 L-L 散射测量的结果一致，并且与光学显微镜确定的晶粒尺寸相当。与 L-L 测量相比，转换后的超声背向散射受前壁反射的影响要小得多，并且它提供了其他任何方式都无法获得的附加微观结构信息。