双散射在漫射超声背向散射测量中的作用。

Contribution of double scattering in diffuse ultrasonic backscatter measurements.

作者信息

Hu Ping, Turner Joseph A

机构信息

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

出版信息

J Acoust Soc Am. 2015 Jan;137(1):321-34. doi: 10.1121/1.4904920.

DOI:10.1121/1.4904920

PMID:25618063

Abstract

Diffuse ultrasonic backscatter measurements are used to describe the effective grain scattering present during high frequency ultrasonic inspections. Accurate modeling of the backscatter is important for both flaw detection and microstructural characterization. Previous models have been derived under the assumption of single scattering for which the ultrasound is assumed to scatter only once in the time between excitation and detection. This assumption has been shown to be valid in many experiments for which the time scales are short or the frequency is sufficiently low. However, there are also many instances (e.g., for strongly scattering materials, unfocused beams, or long propagation paths) for which the single scattering assumption appears to break down. In this article, a model for the double scatter is developed within the previous formalism based on Wigner distribution functions. The final expression allows the effect of double scattering to be estimated for any combination of experimental parameters. The improved proposed model is anticipated to increase the capabilities of ultrasonic microstructural evaluation, especially in terms of probability of detection estimates.

摘要

漫射超声背散射测量用于描述高频超声检测过程中存在的有效晶粒散射。背散射的精确建模对于缺陷检测和微观结构表征都很重要。先前的模型是在单次散射假设下推导出来的，在这种假设中，超声在激发和检测之间的时间内仅散射一次。在许多时间尺度较短或频率足够低的实验中，这一假设已被证明是有效的。然而，也有许多情况（例如，对于强散射材料、非聚焦光束或长传播路径），单次散射假设似乎不再成立。在本文中，基于维格纳分布函数，在先前的形式体系内开发了一种双散射模型。最终表达式允许针对任何实验参数组合估计双散射的影响。预计改进后的模型将提高超声微观结构评估的能力，特别是在检测概率估计方面。