Accurate depth measurement of small surface-breaking cracks using an ultrasonic array post-processing technique
Accurate depth measurement of small surface-breaking cracks using an ultrasonic array post-processing technique
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DOI：
10.1016/j.ndteint.2014.08.004
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发表时间：
2014-12-01
影响因子：
4.2
通讯作者：
Wilcox, Paul D.
中科院分区：
文献类型：
--
作者：
Felice, Maria V.;Velichko, Alexander;Wilcox, Paul D.
本文利用全聚焦法的半跳跃结构对表面断裂裂纹进行成像和尺寸测量。TFM是一种超声阵列后处理技术，用于对目标区域内的每个像点进行综合聚焦。本文考虑的情况下，检查裂纹已开始从远表面的平行侧的样品使用的近表面上的阵列。通常，只有阵列和图像点之间的直接射线路径被包括在TFM算法中，因此针对这种情况获得的图像仅由根部和尖端指示组成：没有捕获来自裂纹面的镜面反射。尖端指示通常具有如此差的信噪比，使得可靠的裂纹深度测量具有挑战性。利用半跳跃TFM，代替使用直接散射信号，使用与已经从后表面反射并且然后已经经历从裂纹面回到阵列的镜面反射的超声波相对应的超声波射线路径来形成图像。该技术被应用到实验和模拟阵列数据，并显示出更大的可靠性比依赖于尖端衍射的方法来测量小裂纹（深度< 1 mm）的深度。2014作者爱思唯尔有限公司出版
In this paper, the half-skip configuration of the Total Focusing Method (TFM) is used to image and size surface-breaking cracks. The TFM is an ultrasonic array post-processing technique which is used to synthetically focus at every image point in a target region. This paper considers the case of inspecting for cracks which have initiated from the far surface of a parallel-sided sample using an array on the near surface. Typically, only direct ray paths between the array and image points are included in the TFM algorithm and therefore the image obtained for this case consists only of root and tip indications: no specular reflection from the crack faces is captured. The tip indication often has such a poor signal-to-noise ratio that reliable crack depth measurement is challenging. With the Half-Skip TFM, instead of using directly-scattered signals, the image is formed using ultrasonic ray paths corresponding to the ultrasound that has reflected off the back surface and has then undergone specular reflection from the crack face back to the array. The technique is applied to experimental and simulated array data and is shown to measure the depth of small cracks (depth < 1 mm) with greater reliability than methods which rely on tip diffraction. 2014 The Authors. Published by Elsevier Ltd.