Non-destructive Testing Based on the Spatio-temporal Gradient Analysis over the Lamb Wave Field
Non-destructive Testing Based on the Spatio-temporal Gradient Analysis over the Lamb Wave Field
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DOI：
10.9746/sicetr1965.39.800
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发表时间：
2003-09
期刊：
影响因子：
--
通讯作者：
K. Teramoto;K. Tsuruta
中科院分区：
文献类型：
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作者：
K. Teramoto;K. Tsuruta
提出了一种基于兰姆波场时空梯度分析的缺陷表征方法。在层的方向上传播的表面超声波是无损评价（NDE）方法的潜在候选者。所提出的方法具有通过定义在四维向量空间的协方差矩阵的秩来对表面声波场进行分类的能力，所述四维向量空间由以下分量构成：垂直位移、垂直速度和表面的一对剪切应变。协方差矩阵提供关于缺陷的信息。因此，协方差矩阵的行列式，建议作为指标的均匀性的对象表面。本文讨论了缺陷附近波场的计算过程，并通过时域有限差分（FDTD）模拟和声学实验研究了缺陷附近波场的物理意义。
This paper presents a defect characterization method by spatio-temporal gradient analysis over the Lamb wave field. The surface ultrasound waves that propagate in the direction of the layer are potential candidates of non-destructive evaluation (NDE) methodology. The proposed method has an ability to classify the surface acoustic wave field through the rank of the covariance matrix defined over the four-dimensional vector space which is spanned by following components: a vertical displacement, its vertical velocity, and a pair of shear strains of the surface. The covariance matrix provides the information about defects. The determinant of the covariance matrix, therefore, is proposed as the index of homogeneity of the object surface. In this study, the computational process in wave field near the defects is discussed and their physical meanings are investigated through FDTD-simulations and acoustic experiments.