摘要
基于超声波声弹性理论,通过理论计算方法探讨了互相关步长对低信噪比超声波评价应力的影响.以振荡衰减余弦波为基础函数,通过叠加高斯白噪声获得染噪信号,改变降噪参数获得低信噪比超声波模拟信号,基于互相关系数函数理论澄清互相关步长对应力评价的影响机理.结果表明:随互相关步长增大,互相关系数函数曲线逐渐平滑,最大值逐渐明显,超声波传播时间差随应力增大逐渐呈严格线性增大;当互相关步长达到1周期,再随互相关步长增大,互相关系数函数曲线及超声波传播时间差与应力间曲线基本重合.分析认为噪声引起的超声波波形畸变是导致上述结果的主要原因.
Based on ultrasonic acoustoelastic theory,the influence of cross correlation step length on stress evaluation of low signal noise ratio ultrasonic waves was discussed with theoretical calculation method. Based on damped oscillation cosine signals,Gauss white noise was superposed,and the low signal noise ratio ultrasonic wave was obtained with different denoising methods. The influence mechanism of cross correlation step length on stress evaluation was clarified with cross correlation coefficient theory. The results show that as cross correlation step length increases,the cross correlation coefficient function curve is more smooth and the maximum value increases gradually; the linear degree of relationship between the difference in time of flight and stress also increases; when cross correlation step length attains one cycle,cross correlation coefficient function curve and the curve of the difference in time of flight and stress overlap basically. The waveform distortion caused by noise is the main reason for the above results.
出处
《江苏科技大学学报（自然科学版）》
CAS
北大核心
2017年第1期26-30,共5页
Journal of Jiangsu University of Science and Technology:Natural Science Edition
基金
国家自然科学基金资助项目(51305172)
中国博士后科学基金资助项目(2016M591795)
关键词
信噪比
互相关步长
时间差
应力评价
signal noise ratio
cross correlation step length
difference in time of flight
stress evaluation
