摘要
超声Lamb波在工业无损检测与评价中具有广阔的应用前景。但受制于超声导波多模式频散与混叠的影响,如何实现高分辨率超声导波的模式分离与频散曲线提取,进而定量分析材料的健康状况一直是研究的热点与难点。本文旨在将现代信号处理中广泛采用的谱估计技术应用于超声Lamb波阵列信号分析,并通过提取频散曲线定量测量板厚度。以经典参数谱估计法中的Yule-Walker法与Burg法为例,实验测量和分析了3mm,4mm和5mm厚铝板中的宽带多模式Lamb波信号,准确地提取了铝板中的宽带Lamb波频散曲线,并比较了两种经典谱估计方法与二维傅氏变换法的性能,最终实现了铝板厚度估计。
As one of the most promising technologies,ultrasonic Lamb waves have been widely analyzed in the non-destructive evaluation.However,due to the guided dispersion and mode overlap,mode identification and dispersion determination are still challenging,thereby attacting considerable attentions.Here,we use two traditional spectrum estimation methods,i.e.,the Yule-Walker method and the Burg method to analyze the array-transducer signals for high-resolution ultrasonic Lamb waves dispersion measurement.An inverse method was also designed to estimate the aluminum plate thickness from the extracted wideband dispersion curves.Experiments on three aluminate plates with different thicknesses(3mm,4mm and 5mm)demonstrated that the spectrum estimation methods were helpful for the ultrasonic Lamb waves based non-destructive evaluation.
引文
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