正交异性钢桥面板声发射波三维谱元法模拟及损伤定位*

针对大跨度桥梁正交异性钢桥面板的疲劳损伤评估与结构健康监测需求，开展基于声发射波场谱元法模拟的大型复杂板类结构损伤定位研究。采用Legendre高阶插值三维时域谱元法模拟声发射波在正交异性钢桥面板中的传播过程，验证了其内部显著的反射、衍射和频散现象，并代替人工预断铅实测试验获得大量声发射数据。然后，利用赤池信息准则判定声发射波到达各传感器的时间，通过高斯过程回归建立到达时差与声发射源位置的关系模型，用于未知损伤的定位监测。数值模型实验结果表明，赤池信息准则和高斯过程回归改进的时差图法在正交异性钢桥面板中的平均定位误差为37.3 mm(25 dB信噪比工况)，平板的定位精度高于U肋。谱元法模拟有望代替繁琐的预断铅实测试验，提升声发射时差图系列损伤定位方法的实用性。

Three-dimensional spectral element simulation of acoustic emission waves and damage location in orthotropic steel bridge decks

According to the fatigue damage evaluation and structural health monitoring demand of orthotropic steel bridge decks of long-span bridges, damage location in large-scale complex plate structures was investigated through spectral element simulation of acoustic emission wave field. Legendre high-order interpolation based three-dimensional time-domain spectral element method was introduced to simulate acoustic emission waves propagating in orthotropic steel bridge decks, where significant reflection, diffraction and dispersion phenomena were observed as expected. Then, abundant acoustic emission data were obtained through spectral element simulation, instead of the manual pencil lead break pre-tests. After that, the Akaike information criterion was used to determine the arrival times of acoustic emission waves at different sensors. A relationship model between the arrival time differences of acoustic emission waves and the coordinates of acoustic emission sources was established by Gaussian process regression, which would be used to locate unknown damages. Numerical simulation results showed that the improved delta-T mapping method based on Akaike information criteria and Gaussian process regression achieved an average location error of 37.3 mm (for the case of 25 dB signal-to-noise ratio) in the orthotropic steel bridge deck, where the location of the plate was more accurate than that in the U-shaped rib. It was demonstrated that spectral element simulation provided a promising approach to substitute the tedious pencil lead break pre-tests and therefore to improve the practicability of acoustic emission damage location based on the series of delta-T mapping methods.