榫卯结构弯曲破坏时声发射衰减特性与源定位

由于木结构榫卯接合的部位属于隐藏部位，当其发生损伤时，肉眼无法观测。为了准确地预测榫卯结构的健康状况, 可以根据榫卯结构在破坏前，木材所释放出来的声发射能量传播特性进行信息源位置的判定。为此, 本研究提出并验证了木材的声发射信号符合能量衰减规律，并且利用能量衰减模型对榫卯结构的声发射源(破坏源)进行定位。首先，采用直径0.5 mm的铅芯为模拟声发射源，探讨了声发射波在木材中的传播和衰减特性，然后进行了榫卯结构弯曲破坏实验，实验中将目标声发射源限定于两个传感器之间，利用两点定位法确定破坏源的位置, 经比较计算值与实测值较一致。结果表明:基于AE信号能量衰减模型和两点定位法进行榫卯结构的损伤定位，能得到较准确的破坏源位置，而且外界环境对结果的影响较小。 

Acoustic emission attenuation and source location on the bending failure of the rectangular mortise-tenon joint for wood structures

Since the mortise-tenon joints of wood structures are hidden members, the fracture location of the mortise-tenon joints could not be tested accurately by naked eyes. In order to predict accurately the health condition of the mortise-tenon joints, acoustic emission information location could be detected according to the propagation properties of acoustic emission energy released by wood before the mortise-tenon joints fracture. Energy attenuation law of the acoustic emission signal for wood was verified in this paper, and a new method was proposed to locate the damage of mortise-tenon joints based on energy attenuation model for wood. Firstly, using 0. 5 mm diameter pencil lead as artificial acoustic emission source, acoustic emission wave propagation and attenuation characteristics were discussed for wood. And then the bending failure experiments of the mortise-tenon joints were studied. In the process of the experiments, acoustic emission source was located between the two sensors, and two-point positioning method was used to determine the fracture location of the mortise-tenon joints. The calculation values of the fracture location agreed with the experimental ones. The results show that the positioning method could acquire accurate fracture location based on energy attenuation model of the AE signal and two-point method, and the results are less affected by the external environment.