摘要
研究了数字相关法在超声应力检测中回波时间差的自动识别计算。采用数字模拟分析,对相关运算算法的可靠性进行了验证。分析了不同采样频率和相关窗口长度对相关计算的影响,并应用插值技术提高了时间差的计算精度。该方法对实验采集的超声纵波、横波及表面波的时间差分析均适用。通过对不同应力状态下采集的超声表面波信号的处理,得到了Q235钢中超声表面波传播时间差与应力的实验关系曲线,为超声应力检测奠定了基础。
To improve the detection accuracy of the time difference in acoustoelastic experiments, the Digital Correlation Method is used to identify the time difference between two ultrasonic wave signals. The reliability and accuracy of the Digital Correlation Method is validated by a digital simulation. The identification accuracy varies with different sample frequencies and length of the correlation window. Furthermore, a cubic spline interpolation technique is applied to enhance time difference identification. The proposed method enables to identify for the longitudinal wave, transverse wave and surface wave signals sampled at different stress levels. The surface wave acoustoelastic coefficients of the Q235 steel can be obtained from the experimental relationship between the surface wave propagation time difference and the surface stress under different loadings.
出处
《应用力学学报》
EI
CAS
CSCD
北大核心
2008年第1期158-161,共4页
Chinese Journal of Applied Mechanics
关键词
相关法
超声检测
时间差
信号识别
Digital Correlation Method, ultrasonic detection, time difference, signal identification.