超声导波针对均匀腐蚀的无基准评定方法

Baseline-free method for the evaluation of uniform corrosion based on ultrasonic guided waves

考虑了源于时频分析的固有不确定性对测量精度的影响,运用超声导波对加速腐蚀试验条件下的钢丝剩余直径量进行了无基准评定。选择了导波针对均匀腐蚀程度具有较高分辨率的频率段,并利用局部的频散关系建立了一个基于二元显式测量函数的近似直径表达式,以避免后续对复杂Pochhammer方程的多次求解;对接收信号进行小波相关性分析,并推导了基于复Morlet小波的时间-频率不确定度定量表达式;将基于GUM法与自适应蒙特卡洛法(MCM)求解所获取的直径评定结果进行了对比验证,证明了运用GUM法可更为高效地评定构件的均匀腐蚀状态。

Considering the influence of inherent uncertainties originated from the procedure of time-frequency analysis on the measurement accuracy,the residual diameter of a steel wire in accelerated corrosion experiment was evaluated with a baseline-free method of guided waves.Confirming the frequency region with high resolution in the uniform corrosion level,a binary explicit measuring function for approximately estimating the diameter was established according to the dispersive characteristics of ultrasonic guided waves,instead of repeatedly solving the Pochhammer equation in the successive analysis.The wavelet correlation analysis of the received signals was carried out,and a quantitative formula for the uncertainty based on the complex Morlet wavelet was specifically deduced.Comparing the results derived from the GUM and self-adaptive Monte Carlo method(MCM),it is proved that the GUM method can be used to evaluate the uniform corrosion of the component much more efficiently.