Zeroug S
Schlumberger-Doll Research, Ridgefield, CT06877, USA.
IEEE Trans Ultrason Ferroelectr Freq Control. 2000;47(3):565-74. doi: 10.1109/58.842043.
Quantitative modeling of ultrasonic pulse-echo and pitch-catch measurements for non-destructive evaluation (NDE) of bulk or layered fluid-immersed elastic materials is important for optimal measurement design, data interpretation, and parameter inversion. Just as important is the computational efficiency of the resulting numerical algorithms to ensure that they are exploited effectively. For defect-free configurations consisting of planar and cylindrical homogeneous and isotropic layers, analytical modeling, employing spectral integral decomposition and synthesis, offers a powerful tool to meet this requirement. The analytical approach allows the expression of the receiving transducer voltage and the beam-structure interaction in terms of a spectral wavenumber integral. Within this representation, transducer beams are specified in terms of their pressure or normal velocity spectra or, alternatively and more conveniently, in terms of Gaussian beams generated through the complex transducer point (CTP) technique. The voltage integrals may be implemented numerically or reduced to closed-form solutions via high frequency asymptotic techniques. This article summarizes the theory, discusses its numerical implementation, and illustrates its applications through two time-domain measurements. The first pertains to a pulse-echo measurement conducted from inside a cylindrically layered structure and for which the theoretical predictions are successfully validated by experimental data. The second pertains to a pitch-catch measurement to generate and detect leaky Lamb waves in a plate. For this latter case, uniform asymptotics, validated by comparisons with numerical integration, is used to isolate the contributions of the various Lamb modes to the total voltage.
对块状或层状流体浸没弹性材料进行无损评估（NDE）的超声脉冲回波和 pitch-catch 测量的定量建模，对于优化测量设计、数据解释和参数反演非常重要。同样重要的是所得数值算法的计算效率，以确保它们能得到有效利用。对于由平面和圆柱形均匀各向同性层组成的无缺陷结构，采用谱积分分解与合成的解析建模提供了一个强大的工具来满足这一要求。解析方法允许根据谱波数积分来表示接收换能器电压和波束结构相互作用。在此表示中，换能器波束根据其压力或法向速度谱来指定，或者更方便地，根据通过复换能器点（CTP）技术生成的高斯波束来指定。电压积分可以通过数值方法实现，或者通过高频渐近技术简化为封闭形式的解。本文总结了该理论，讨论了其数值实现，并通过两个时域测量说明了其应用。第一个涉及从圆柱形分层结构内部进行的脉冲回波测量，其理论预测已通过实验数据成功验证。第二个涉及在板中生成和检测泄漏兰姆波的 pitch-catch 测量。对于后一种情况，通过与数值积分比较验证的均匀渐近法用于分离各种兰姆模对总电压的贡献。
