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On the theoretical limitations in estimating thickness of a plate-like structure from a full-field single-tone response Lamb wave measurement
Ultrasonics ( IF 4.2 ) Pub Date : 2020-12-01 , DOI: 10.1016/j.ultras.2020.106230
Nicholas Stull 1 , Eric Flynn 1 , Matthew Mascarenas 2
Affiliation  

A persistent question in wavenumber analysis in the estimation of thickness from a steady-state wave field is identifying the theoretical sensitivity of the system. A well-known trade-off between spatial frequency/wavenumber resolution and thickness resolution exists. The current work presents a calculation of the Cramer-Rao Lower bound (CRLB), specifically as applied to thickness estimates, for a 2-dimensional multi-mode waveform in Gaussian noise. Cases of near-field and far-field excitation are considered, and transducer position with respect to the scan area is also varied. Additionally, we consider the CRLB in a plate with multiple sources, simulated as sources placed on the boundary of the plate. We conclude by presenting the CRLB values in terms of frequency for various thicknesses, and by presenting optimal excitation frequencies for a nominal thickness, based on the CRLB.

中文翻译:

从全场单音响应兰姆波测量估计板状结构厚度的理论局限性

从稳态波场估计厚度的波数分析中一个持续存在的问题是确定系统的理论灵敏度。存在空间频率/波数分辨率和厚度分辨率之间的众所周知的权衡。当前的工作提出了 Cramer-Rao 下界 (CRLB) 的计算,特别是应用于厚度估计,用于高斯噪声中的二维多模波形。考虑了近场和远场激励的情况,并且换能器相对于扫描区域的位置也发生了变化。此外,我们考虑了具有多个源的板块中的 CRLB,模拟为放置在板块边界上的源。最后,我们根据不同厚度的频率呈现 CRLB 值,
更新日期:2020-12-01
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