基于奇异谱和相关性分析的木材声发射源直线定位算法研究

针对木材声发射（acoustic emission,AE）信号的随机特性，提出了一种基于奇异谱和信号相关性分析的木材表面AE源直线定位算法。首先，依据ASTM标准通过折断铅芯的方式分别在樟子松和榉木试件表面产生AE源，并在顺纹理方向布置2个AE传感器，其中采样频率设置为500 kHz。然后，采用奇异谱分析（singular spectrum analysis，SSA）算法提高AE信号的信噪比，再分别基于信号相关性和最大值分析2种方法计算AE信号在木材表面顺纹理方向的传播速度。最后，依据AE信号传播时差和计算速度，基于时差定位原理设计AE源定位算法。并针对SSA处理前后的AE信号，采用不同定位算法进行比较试验。结果表明，直接对原始AE信号采用基于信号相关性和最大值分析方法确定信号传播速度时，樟子松试件2个不同位置AE源的定位误差分别为51.8%、55.7%和75.7%、46.6%；榉木试件2个不同位置AE源的定位误差分别为52.0%、44.8%和37.7%、45.5%。而对于经SSA处理后的AE信号，樟子松试件相应的定位误差分别为5.1%、33.2%和2.6%、31.7%；榉木试件相应的定位误差分别为3.1%、54.9%和5.1%、22.9%。因此，对原始AE信号进行SSA降噪处理后，再基于信号相关性分析方法确定信号传播速度，能够显著提高木材表面AE源的定位精度。

Straight Line Location Algorithm of Wood Acoustic Emission Source Based on Singular Spectrum Analysis and Signal Correlation Analysis Methods

A linear localization algorithm for AE sources on wood surfaces was proposed based on singular spectrum and signal correlation analysis for the random characteristics of wood acoustic emission (AE) signals.Firstly,AE sources were generated on the surfaces of Pinus sylvestris var.mongolica and Zelkova schneideriana specimens by breaking lead cores according to ASTM standards,and two AE sensors were arranged in the down-grain direction,where the sampling frequency was set to 500 kHz.Secondly,the singular spectrum analysis (SSA) algorithm was used to improve the signal-to-noise ratio of the AE signal,and then the propagation speed of the AE signal along the grain direction on the wood surface was calculated based on two methods of signal correlation and maximum value analysis.Finally,according to the time difference of AE signal propagation and calculation speed,the AE source positioning algorithm was designed based on the time difference positioning principle.For the AE signals before and after SSA processing,different positioning algorithms were used for comparative experiments.The test results showed that when the original AE signal was directly used to determine the signal propagation speed based on the signal correlation and maximum value analysis methods,the positioning errors of the AE source at two different positions of the P.sylvestris var.mongolica specimen were 51.8%,55.7% and 75.7%,46.6%,respectively.The corresponding positioning errors for the Z.schneideriana specimen were 3.1%,54.9% and 5.1%,22.9%,respectively.Therefore,the SSA noise reduction process of the original AE signal,followed by the determination of the signal propagation speed based on the signal correlation analysis method,can significantly improve the localization accuracy of the AE source on the wood surface.