基于小波变换的超声多模式兰姆波参量时延估计

Parameter and time delay estimation of ultrasonic multi-mode Lamb waves based on wavelet transform

提出了采用小波瞬时参数法和小波变换模极大值法分别对高频窄带和低频宽带超声多模式（Ａ０模式和Ｓ０模式）兰姆波进行时延估计，与希尔伯特瞬时参数法比较，它们的估计精度明显的高于希尔伯特瞬时参数法，其中小波变换的模极大值法对时延估计的精度最高，小波瞬时参数法次之，希尔伯特瞬时参数法不能很好的估计多模式时延。同时提出了基于小波变换模极大值重建对超声兰姆波多模式估计衰减系数的方法，对金属铝薄板的实验结果表明此方法是可行的。

This paper put forward using Wavelet Instantaneous Parameter Methods (WIPM) and the modulus maxima method of the Wavelet Transform(WTM),respectively, for time delay estimations of narrow-band and wide-band multi-mode(A0 and S0)Lamb waves.The methods are much higher resolution than Hilbert Instantaneous Parameter Methods(HIPM). WTM's resolution is the highest;WIPM's resolution is the second; and HIPM can not magnificently estimate the multi-mode time delay.Synchronously this paper puts forward the method of the reconstruction based on wavelet Transform modulus maxima to estimate attenuation coefficient of multi-mode ultrasonic Lamb wave A0 and S0. And the method indicated by experiment results is feasible for metal aluminum thin plate.