马尾松胶合木胶层对声发射信号传播特性的影响

采用NI高速采集设备构建木材声发射信号采集平台,通过铅芯折断的方式在马尾松胶合木表面模拟产生AE源。然后对采集的原始信号进行5层小波分解并重构AE信号波形,进而获得AE信号的时频域特征。最后,根据信号相关性分析和时差定位方法,研究AE信号沿胶接横纹和指接横纹方向上的传播速率。研究表明,AE信号在胶合木表面传播时,AE信号中频率较低的成分在通过胶层时能量衰减更加显著,并且在胶接横纹和指接横纹方向上的传播速率存在明显差异,进一步指出指接胶层对信号传播速率的影响比胶接胶层更明显。

Influence of Adhesive Layer at Masson Pine Glulam on Acoustic Emission Signal Propagation Characteristics

In order to study the acoustic emission (AE) nondestructive testing of glulam,the influence of adhesive layer on AE signal waveform characteristics and its propagation rule were studied.Firstly,NI high-speed acquisition equipment was used to build a wood acoustic emission signal acquisition platform,and an artificial AE source was created through breaking off the pencil lead on the surface of the masson pine.Then,five layers of wavelet decomposition were performed on the original signals,and the real AE signal were reconstructed.Time domain and frequency domain characteristics were obtained from the reconstructed waveform.Finally,according to the correlation analysis method and the approach of time difference location,the propagation velocity of AE signal along the direction of glue joint perpendicular grain and finger joint perpendicular grain were studied.The results showed that the lower frequency components of AE signal attenuated more significantly when passing through the adhesive layer.The propagation velocities of AE signals in the two directions were obviously different.It further concluded that influence of the finger joint adhesive layer for signal propagation velocity was more significant than the glue joint adhesive layer.