用改进的Kirchhoff近似方法对非均匀介质中缺陷形状重构

Shape Reconstruction of Flaws Using Modified KIRCHHOFF Approximation in Inhomogeneous Materia

摘要: 近年来关于波在非均匀介质中传播特性方面的研究引起了各领域专家、学者的广泛关注。本文首先导出了非均匀介质中散射体散射截面??P?的表达式，对含不相关散射体及含相关散射体的非均匀介质中的Kramers-Kronig关系的相值进行量化，并且以变化的频率为桥梁，引入相速度构造非均匀介质中的二维Kirchhoff近似公式，最后通过实验的方法获取数据应用此公式对非均匀介质中的缺陷形状进行重构，重构的结果反映了理论公式的可行性。

Abstract: In recent years, research on propagation characteristic of wave in inhomogeneous media attracts much attention among experts and scholars in various domains. First, mathematic expression for scattering cross section ??P? in inhomogeneous is deduced. Then, quantization of Kramers-Kronig relation in inho-mogeneous medium containing scatterers is given. Based on the frequency change, the phase velocity due to the inhomogeneous material is introduced into two-dimensional Kirchhoff approximation formula. Finally, this paper reconstructs the flaw shapes in inhomogeneous medium using backscattered ultrasound through experimental method and the results verify the feasibility of flaw scattering theory.