小波高阶统计量的时延估计及在超声应力检测中的应用

应力-时延模型是超声应力检测的基础,但对时延分辨率的要求极高,一般在ns量级,对于某型火箭发动机金属基复合材料的应力检测来说,多层叠加信号高度重叠以及噪声的影响,给时延估计带来极大的困难;利用小波高阶统计量理论对超声应力回波系统进行建模,提取叠加信号中时延信息,最后应用到金属基复合材料结构金属层的应力检测,试验结果是令人满意的。

Time Delay Estimation Based on Wavelet-high Order statistics theory and Its Application in Ultrasonic Stress Test

Stress-time delay model is the theoretical basis of ultrasonic stress test,but it demands a excessive time delay resolution,which is at ns level generally.To the stress testing of MMCS of some kind of rocket engine,the influence of multilayer superposition signal and noise introduces most difficulty in time delay estimation.In this paper wavelet-high order statistics is used to model ultrasonic stress echo system and to extract time delay information in superposition signal.When the method is applied to metal layer stress testing of MMCS,the result is satisfactory.