EI / SCOPUS / CSCD 收录

中文核心期刊

增强颗粒散射中缺陷回波信号的相关加权分离谱方法

Flaw-to-grain echo enhancement by cross-correlation weighting and split-spectrum processing

  • 摘要: 粗晶材料的超声无损检测受背散射的影响,使得其信噪比很低,且这里的噪声是与发射超声波相干的噪声,不能用简单的时间平均来消除。分离谱技术已被证明是一种抑制背散射信号、提高信噪比的良好方法,许多人为此发展了各种理论作为分离谱的后处理算法。本文介绍了一种增强超声回波信号的相关加权前处理算法。这里,取自粗晶材料标准缺陷的窄脉冲超声回波被定义为标准子波,利用子波与超声检测信号的互相关作为权系数对检测信号进行加权,此技术与分离谱处理结合起来能使提高信噪比的性能更优。实验结果显示了本文所述方法可改善诸如奥氏体不锈钢一类粗晶材料超声检测的信噪比

     

    Abstract: Ultrasonic nondestructive testing of coarse grained materials is limited by the signal-to-noise ratio (SNR) because of backscattering noise.This type of noise is coherent and its effects cannot be reduced by time averaging techniques.Split spectrum signal processing (SSP) has proven to be effective in improving the SNR of backscattered signals.Many authors have developed frequency splitting theory as the postprocessor.This paper introduces a cross-correlation weighted method as the preprocessor for ultrasonic echo signal enhancement.A short ultrasonic echo from a typical defect in large grained materials is defined as standard ultrasonic wavelet.Then the cross-correlation function between the wavelet and an ultrasonic testing signal is used as weight function for the testing signal.This technique and split-spectrum processing can be combined to achieve better Performance.Experimental results are presented to demonstrate the effectiveness of ultrasonic testing in coarse grained materials such as austenitic stainless steel.

     

/

返回文章
返回