Bai Long, Velichko Alexander, Drinkwater Bruce W
Department of Mechanical Engineering, University of Bristol, Bristol BS8 1TR, United Kingdom.
J Acoust Soc Am. 2018 Jan;143(1):349. doi: 10.1121/1.5021246.
This paper studies ultrasonic defect characterisation with the aim of reducing the characterisation uncertainty. Ultrasonic array data contain a mixture of responses from all reflecting features, and the scattering matrix for each defect can be extracted in post-processing, which describes how ultrasonic waves at a given incident angle are scattered by a defect. In this paper, it is shown that defect characterisation performance can be improved by the inclusion of phase and frequency information relative to current single-frequency-amplitude approaches. This superior characterisation performance is due to the increased number of informative principal components (PCs) and higher signal-to-noise ratios in the PC directions. Scattering matrix phase measurement is very sensitive to localisation errors, and an effective approach is proposed, which can be used to reliably extract phase from experimental data. Nine elliptical defects having different aspect ratios and orientation angles are characterised experimentally. The complex multi-frequency defect database has achieved up to 90.60% reduction in the quantified sizing uncertainty compared to the results obtained using only the amplitude at a single frequency.
本文旨在通过减少表征不确定性来研究超声缺陷表征。超声阵列数据包含来自所有反射特征的混合响应，并且每个缺陷的散射矩阵可以在后处理中提取，该矩阵描述了给定入射角的超声波如何被缺陷散射。本文表明，相对于当前的单频幅度方法，通过纳入相位和频率信息可以提高缺陷表征性能。这种卓越的表征性能归因于信息主成分（PC）数量的增加以及PC方向上更高的信噪比。散射矩阵相位测量对定位误差非常敏感，因此提出了一种有效的方法，可用于从实验数据中可靠地提取相位。通过实验对九个具有不同纵横比和取向角的椭圆形缺陷进行了表征。与仅使用单频幅度获得的结果相比，复杂的多频缺陷数据库已将量化尺寸不确定性降低了高达90.60%。
