Abstract

The TOFD method, widely used in ultrasonic flaw detection, makes it possible to distinguish a crack from a volume reflector by the phase of echo signals and to determine its height with high accuracy. However, the TOFD method without piezoelectric transducers scanning across the welded joint does not allow determining the offset of the reflector from the weld center, which is very important when evaluating the test results. The scanning devices used for this have a complex design, their price is higher than that of one-dimensional scanning devices, and, most importantly, the testing time increases considerably. If we use echo signals reflected from the bottom of the test object, taking into account the change in the wave type, then the combined reflector image can be obtained from the set of partial images reconstructed by the digital antenna focusing (DFA) method. Using the echo signals measured in the combined mode for each piezoelectric transducer, then it is possible to estimate the displacement of the reflector across the welded joint with an accuracy of \( \pm 1.5\) mm. Numerical and model experiments have confirmed the efficiency of the proposed approach.

中文翻译：

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使用 TOFD 方案中的换能器测量的回波信号确定垂直于焊接接头的平面中反射器的坐标

摘要

TOFD方法广泛用于超声波探伤，它可以通过回波信号的相位来区分裂缝和体反射体，并高精度地确定裂缝的高度。然而，没有压电换能器扫描焊接接头的 TOFD 方法无法确定反射器与焊接中心的偏移，这在评估测试结果时非常重要。用于此的扫描设备设计复杂，其价格高于一维扫描设备，最重要的是，测试时间大大增加。如果我们使用从测试对象底部反射的回波信号，考虑到波型的变化，然后可以从通过数字天线聚焦（DFA）方法重建的一组局部图像中获得组合反射面图像。使用以组合模式测量的每个压电换能器的回波信号，然后可以估计反射器在焊接接头上的位移，精度为\( \pm 1.5\)毫米。数值和模型实验证实了所提出方法的有效性。