Darmon M, Dorval V, Kamta Djakou A, Fradkin L, Chatillon S
CEA, LIST, Department of Imaging & Simulation for Nondestructive Testing, F-91191 Gif-sur-Yvette, France.
CEA, LIST, Department of Imaging & Simulation for Nondestructive Testing, F-91191 Gif-sur-Yvette, France.
Ultrasonics. 2016 Jan;64:115-27. doi: 10.1016/j.ultras.2015.08.006. Epub 2015 Aug 21.
Simulation of ultrasonic Non Destructive Testing (NDT) is helpful for evaluating performances of inspection techniques and requires the modelling of waves scattered by defects. Two classical flaw scattering models have been previously usually employed and evaluated to deal with inspection of planar defects, the Kirchhoff approximation (KA) for simulating reflection and the Geometrical Theory of Diffraction (GTD) for simulating diffraction. Combining them so as to retain advantages of both, the Physical Theory of Diffraction (PTD) initially developed in electromagnetism has been recently extended to elastodynamics. In this paper a PTD-based system model is proposed for simulating the ultrasonic response of crack-like defects. It is also extended to provide good description of regions surrounding critical rays where the shear diffracted waves and head waves interfere. Both numerical and experimental validation of the PTD model is carried out in various practical NDT configurations, such as pulse echo and Time of Flight Diffraction (TOFD), involving both crack tip and corner echoes. Numerical validation involves comparison of this model with KA and GTD as well as the Finite-Element Method (FEM).
超声无损检测（NDT）模拟有助于评估检测技术的性能，并且需要对由缺陷散射的波进行建模。此前通常采用并评估两种经典的缺陷散射模型来处理平面缺陷检测，即用于模拟反射的基尔霍夫近似（KA）和用于模拟衍射的几何绕射理论（GTD）。为了兼具两者的优点，最初在电磁学中发展起来的物理绕射理论（PTD）最近已扩展到弹性动力学领域。本文提出了一种基于PTD的系统模型，用于模拟裂纹状缺陷的超声响应。该模型还进行了扩展，以很好地描述临界射线周围的区域，在这些区域中，剪切衍射波和头波会相互干涉。在各种实际的无损检测配置中，如脉冲回波和飞行时间衍射（TOFD），对裂纹尖端和拐角回波进行了PTD模型的数值和实验验证。数值验证包括将该模型与KA、GTD以及有限元方法（FEM）进行比较。
