复合材料板声发射源定位的时间差映射方法

Time difference mapping method for acoustic emission source location of composite plates

针对复合材料板内可能出现的纤维断裂、基体开裂等缺陷以及声波在不同传播方向的传播速度不一致且波速差异较大等问题,提出一种改进的时间差映射方法实现对复合材料板的声发射源定位。该方法采用的是预构建数据库方法,不需考虑波在板中的传播速度不一致以及波的传播模态等问题,而且实验对传感器在板中的布置没有严格要求。首先,为了快速准确地选择和删除采集的大量声发射数据中存在的伪声发射事件,采用聚类算法自动识别和选择每个网格节点上高度相关性的声发射事件并构建时间差训练数据库;其次,为了提高网格分辨率,采用插值补偿算法增加网格密度;最后,针对测试区域验证实际声源的位置,使用加权差分算法实现声源的定位。理论分析和实验结果表明:声源位置的定位平均实际误差从26.5 mm(采用传统的时间差映射方法)降至18.0 mm (采用改进后的时间差映射方法),对应的平均相对误差从5.3%降至3.6%;并且整体运行时间从5 h减少到16.87 s。研究表明改进后的时间差映射方法可有效快速地提高声源的定位结果及精度。

An improved time difference mapping method is proposed to locate the acoustic emission(AE) source of composite plate in order to solve the problems of fiber fracture,the matrix crack defects within composite plate and the acoustic velocity in different propagation direction is inconsistent and difference.This method use the prebuilt database method,avoiding consider the propagation speed of waves in the plate are not consistent and the wave propagation modes,and layout of the sensor in experiments is not strictly required.Firstly,in order to quickly and accurately select and delete the pseudo AE events from a large number of AE data,the clustering algorithm is used to automatically identify and select the highly correlated AE events on each grid node and construct a time difference training database.Secondly,interpolation compensation algorithm is adopted to increase grid density and improve grid resolution.Finally,the location of the source is verified by using the weighted difference algorithm to verify the location of the actual source in the test area.Theoretical analysis and experimental results show that the average actual errors of the location of the sound source is reduced from 26.5 mm(using the traditional time difference mapping method) to 18.0 mm(using the improved time difference mapping method),the corresponding average relative error is reduced from 5.3% to 3.6%,and the overall running time is reduced from 5 h to 16.87 s.The research shows that the improved time difference mapping method can effectively improve the location results and precision of the sound source.