Elastic shear wave scattering by randomly rough surfaces
Elastic shear wave scattering by randomly rough surfaces
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DOI：
10.1016/j.jmps.2019.103852
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发表时间：
2020-04
影响因子：
5.3
通讯作者：
S. Haslinger;M. Lowe;P. Huthwaite;R. Craster;F. Shi
中科院分区：
文献类型：
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作者：
S. Haslinger;M. Lowe;P. Huthwaite;R. Craster;F. Shi
表征弹性介质中的裂纹是超声无损评价（NDE）的一个重要方面，其中飞行时间衍射和脉冲回波等技术通常用于光滑、直裂纹的散射假设。然而，裂缝很少是直的或光滑的，最近的注意力集中在主要由纵波激励的粗糙表面散射上。我们提供了一个全面的研究由入射横波散射，迄今为止被忽视的粗糙表面散射模型，尽管它们在检测表面破碎缺陷的实际重要性，使用建模，仿真和支持实验。入射横波的散射带来了与面波模式转换、Kirchhoff近似（KA）的有效范围与纵向入射相比减小以及相关长度的重要性增加有关的挑战，而这些挑战在纵向情况下基本上不存在。在给定入射角和两个统计参数的情况下，利用统计模型对粗糙缺陷的期望反射进行预测，该模型可即时得到任意散射角和缺陷长度下的期望反射幅度。如果相关长度与缺陷长度之比超过我们确定的临界值，则散射结果与相关长度存在显式依赖关系，我们修改模型以找到这种依赖关系。该模型与许多不同表面轮廓的蒙特卡罗模拟交叉相关，共享相同的统计参数值，使用射线模型（KA）和有限元（FE）方法进行数值模拟，并通过GPU实现加速。此外，我们提供了实验验证，证明了我们的预测的准确性。
Characterizing cracks within elastic media forms an important aspect of ultrasonic non-destructive evaluation (NDE) where techniques such as time-of-flight diffraction and pulse-echo are often used with the presumption of scattering from smooth, straight cracks. However, cracks are rarely straight, or smooth, and recent attention has focussed upon rough surface scattering primarily by longitudinal wave excitations.We provide a comprehensive study of scattering by incident shear waves, thus far neglected in models of rough surface scattering despite their practical importance in the detection of surface-breaking defects, using modelling, simulation and supporting experiments. The scattering of incident shear waves introduces challenges, largely absent in the longitudinal case, related to surface wave mode-conversion, the reduced range of validity of the Kirchhoff approximation (KA) as compared with longitudinal incidence, and an increased importance of correlation length.The expected reflection from a rough defect is predicted using a statistical model from which, given the angle of incidence and two statistical parameters, the expected reflection amplitude is obtained instantaneously for any scattering angle and length of defect. If the ratio of correlation length to defect length exceeds a critical value, which we determine, there is an explicit dependence of the scattering results on correlation length, and we modify the modelling to find this dependence. The modelling is cross-correlated against Monte Carlo simulations of many different surface profiles, sharing the same statistical parameter values, using numerical simulation via ray models (KA) and finite element (FE) methods accelerated with a GPU implementation. Additionally we provide experimental validations that demonstrate the accuracy of our predictions.