粗晶材料缺陷的超声信号及其小波包分析

Ultrasonic Signal and its Wavelet Package Analysis of Defects in a Coarse-grained Material

摘要: 采用计算机化超声信号分析系统,对奥氏体不锈钢粗晶材料缺陷的超声回波信号进行采集和加工.结果表明,小波包技术在粗晶材料缺陷超声信号时频特性的表征中具有明显优越性,并能克服裂谱处理技术的缺点.同时发现噪声主要分布在较高或较低频率的位置,而缺陷信号在中间频率段有较大的幅值分布.利用这一特征,可以根据超声信号小波包分解的结果检测到微弱的粗晶材料缺陷信号.

Abstract: The ultrasonic defect echo of a austenite stainless steel with coarse grains was acqiuired and processed using a developed computerized ultrasonic signal analysis system. Its results indicate that the wavelet package technique is of high dependability to express the bine-frequency property of the ultrasonic signal for defects in the coarse-grained material so as to overcome the weakness of the split-spectrum processing technique. In the meantime it is found that the defect information is distributed at middle frequency band, while noise is distributod at high and low frequency bands. Based on mis feature the ultrasonic defect signal of coarse-grained material can be detected from the wavelet package decomposition, even the echo signal is rather weak.