Velichko Alexander, Wilcox Paul D
Department of Mechanical Engineering, University of Bristol, Bristol, BS8 1TR, United Kingdom.
J Acoust Soc Am. 2008 Jan;123(1):186-96. doi: 10.1121/1.2804699.
The paper describes a general approach for processing data from a guided wave transducer array on a plate-like structure. The raw data set from such an array contains time-domain signals from each transmitter-receiver combination. The technique is based on linear superposition of signals in the frequency domain with some amplitude and phase factors and can be applied to any array geometry and any types of array elements. The problem of finding optimal coefficients, which allow the best resolution to be achieved with the minimum number of array elements, is investigated. It is shown that improvements in resolution are obtained at the expense of sensitivity to noise. A method of quantifying this sensitivity is presented. Results are shown that illustrate the application of the technique to a linear array and an array of circular geometry (containing a single ring of elements). Experimental data obtained from a guided wave array containing electromagnetic acoustic transducer elements for exciting and detecting the S0 Lamb wave mode in a 5-mm-thick aluminum plate are processed with different algorithms and the results are discussed. Generalization of the technique for the case of multimode media is suggested.
本文描述了一种处理来自板状结构上导波换能器阵列数据的通用方法。来自此类阵列的原始数据集包含每个发射 - 接收组合的时域信号。该技术基于频域中信号与一些幅度和相位因子的线性叠加，可应用于任何阵列几何形状和任何类型的阵列元件。研究了寻找最优系数的问题，这些系数能以最少的阵列元件实现最佳分辨率。结果表明，分辨率的提高是以对噪声的敏感性为代价的。提出了一种量化这种敏感性的方法。给出的结果说明了该技术在直线阵列和圆形几何形状阵列（包含单个元件环）中的应用。用不同算法处理了从一个包含电磁声换能器元件的导波阵列获得的实验数据，该阵列用于在5毫米厚铝板中激励和检测S0兰姆波模式，并对结果进行了讨论。建议将该技术推广到多模介质的情况。
