Fatigue crack inspection and characterisation using non-collinear shear wave mixing
Fatigue crack inspection and characterisation using non-collinear shear wave mixing
复制标题
使用非共线剪切波混合进行疲劳裂纹检查和表征
DOI：
10.1088/1361-665x/ab5486
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发表时间：
2020-05-01
影响因子：
4.1
通讯作者：
Croxford, Anthony
中科院分区：
文献类型：
--
作者：
Lv, Hongtao;Zhang, Jie;Croxford, Anthony
近年来，非线性超声技术在其早期发展阶段的缺陷检测和表征方面得到了迅速发展。在本文中，非共线剪切波混合用于疲劳裂纹检测和表征，探讨如何可能确定的方向和大小。这是通过测量从感兴趣的裂纹产生的纵波的振幅来实现的。该振幅是两个入射剪切波的相互作用角和频率比的函数，并且由此产生的振幅参数空间被称为裂纹的非线性指纹。数值分析的两个入射剪切波和裂纹之间的非线性相互作用，使用二维有限元模型，以探索一个更广泛的参数空间比可能的实验。结果表明，导致产生最大纵波振幅的相互作用角与裂纹的方位角有关。为了证实这些结论，该模型进行了验证，使用实验测量的垂直疲劳裂纹生长，使用三点弯曲试验从起始缺口。极性翻转方法被用来提高在这样的测量中的信噪比。结果表明，有一个很好的协议之间的实验测量指纹和使用有限元方法模拟。最后，介绍了一种确定疲劳裂纹尺寸的近似方法，该方法使用沿裂纹长度沿着的多次非共线测量来确定其程度。正如预期的那样，所提出的方法的测量尺寸表明，由于闭合疲劳裂纹无法用线性阵列检测到，因此裂纹长度大于用线性超声相控阵图像观察到的裂纹长度。
In recent years, nonlinear ultrasonic techniques have been developed rapidly for defect detection and characterization at its early development stage. In this paper, non-collinear shear wave mixing is used for fatigue crack detection and characterization, exploring how orientation and size may be determined. This is achieved through measuring the amplitude of the generated longitudinal wave from a crack of interest. This amplitude is a function of the interaction angle and frequency ratio of two incident shear waves and the resulting amplitude parameter space is termed the nonlinear fingerprint of the crack. Numerical analysis of the nonlinear interaction between two incident shear waves and cracks was performed using two-dimensional finite element models to explore a broader parameter space than possible experimentally. It is shown that the interaction angle which leads to the maximum generated longitudinal wave amplitude is related to the orientation angle of the crack. To confirm these conclusions the model was validated using experimental measurements of vertical fatigue cracks grown using 3-point bending tests from initiation notches. The polarity flipping method was used to improve signal to noise ratio in such measurements. It is shown that there is a good agreement between the experimentally measured fingerprints and those simulated using finite element methods. Finally, an approximate method for sizing fatigue cracks was introduced that uses multiple non-collinear measurements along the crack length to determine its extent. As expected, the measured sizes from the proposed method indicate greater crack lengths than seen with linear ultrasonic phased array images due to the closed fatigue cracks being undetectable with linear arrays.