THE INTERACTION OF LAMB WAVES WITH DEFECTS
THE INTERACTION OF LAMB WAVES WITH DEFECTS
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DOI：
10.1109/58.143172
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发表时间：
1992-05-01
影响因子：
3.6
通讯作者：
CAWLEY, P
中科院分区：
文献类型：
--
作者：
ALLEYNE, DN;CAWLEY, P
用有限元方法研究了单个兰姆波与各种缺陷的相互作用，并对结果进行了实验验证。数值结果与实验结果非常吻合，并表明作者开发的二维傅里叶变换方法可用于定量实验和数值研究中与缺陷的兰姆波相互作用。结果表明，单个兰姆波对特定缺口的灵敏度取决于频率-厚度积、模态类型（对称或反对称）、模态阶数和缺口的几何形状。本文预测了不同频率-厚度区域的Lamb模a1、a0和50对模拟缺陷的灵敏度是缺陷深度与板厚之比（h/2d）的函数，结果表明，当波长与缺口深度之比为40数量级时，Lamb波可以用来寻找缺口。当陷波宽度较波长小时，透射和反射幅值对宽度变化不敏感，因此控制参数为陷波深度与板厚之比。数值和实验结果都表明，兰姆波通过缺陷的传输率与频率高度相关，特别是在较高的频率厚度下。传输曲线中最大值和最小值的位置是缺口深度的函数，这表明监测传动比随频率的变化可以提供缺陷尺寸的方法。
The interaction of individual Lamb waves with a variety of defects simulated by notches has been investigated using finite-element analysis, the results being checked experimentally. Excellent agreement has been obtained between the numerical and experimental results and it has been shown that a two-dimensional (2-D) Fourier transform method that the authors have developed may be used to quantify Lamb wave interactions with defects in both experimental and numerical investigations. The results have shown that the sensitivity of individual Lamb waves to particular notches is dependent on the frequency-thickness product, the mode type (symmetric or antisymmetric), the mode order, and the geometry of the notch. The sensitivity of the Lamb modes a1, a0, and s0 to simulated defects in different frequency-thickness regions has been predicted as a function of the defect depth to plate thickness ratio (h/2d) and the results have indicated that Lamb waves may be used to find notches when the wavelength to notch depth ratio is of the order of 40. It has also been shown that provided the notch width is small compared to the wavelength, the transmission and reflection amplitudes are insensitive to changes in width, so the ratio of the depth of the notch to the plate thickness is the controlling parameter. Both the numerical and experimental results have shown that the transmission ratios of Lamb waves across defects are highly frequency dependent, particularly at higher frequency-thicknesses. The positions of the maxima and minima in the transmission curves are a function of notch depth that suggests that monitoring the change in transmission ratio with frequency may provide a means of defect sizing.