基于COMSOL的木材黏弹性声发射传播行为仿真及其波速估计

Simulations of Wood Viscoelastic Acoustic Emission Propagation Behavior and Wave Velocity Estimation Based on COMSOL Software

为了研究木材黏弹性特征对声发射(AE)信号传播行为的影响,在COMSOL软件中通过设定木材的黏度系数建立木材试件的有限元仿真模型,并结合木材AE试验结果验证了仿真模型的有效性。首先,在杉木试件表面距离左端面100 mm处通过信号发生器产生Hanning窗调制正弦脉冲信号,并在试件表面距离左端面300 mm处以200 mm间距放置2个AE传感器采集AE信号,再采用滤波器将传感器采集到的AE信号进行去噪处理。其次,对杉木试件进行有限元模拟,得到弹性波在试件中传播的位移云图和在黏弹性材料中的传播规律。最后,通过到达时间差法(Time Difference of Arrival,TDOA)对模拟仿真与试验测量得到的横纵波速度以及时域波形图进行对比。结果表明,模拟仿真所得横纵波速度分别为1118 m/s和5245 m/s,试验所得横纵波速度分别为1290 m/s和5209 m/s。将仿真模拟波形信号图与试验实测波形图进行对比,其幅值衰减与信号时域波形图都较为吻合。因此,证实了黏弹特性对杉木试件的影响以及仿真模型的有效性。

In order to study the influence of wood viscoelasticity characteristics on the propagation behavior of acoustic emission(AE)signals,a finite element simulation model of wood specimens was established by setting the viscosity coefficients of wood in COMSOL software.The effectiveness of the simulation model was verified by combining the results of wood AE experiments.Firstly,a Hanning window modulated sine pulse signal was generated by a signal generator at a distance of 100 mm from the left end face on the surface of the fir specimen.Two AE sensors were placed at a distance of 200 mm from the left end face at a distance of 300 mm on the surface of the specimen to collect the AE signals.Then,a filter was used to denoise the AE signals collected by the sensors.Secondly,finite element simulations were conducted on the fir specimen to obtain the displacement cloud map of elastic wave propagation in the specimen and the propagation law in viscoelastic materials.Finally,the time difference of arrival(TDOA)method was used to compare the transverse and longitudinal wave velocities and time-domain waveforms obtained from the simulations and experimental measurements.The results showed that the simulated transverse and longitudinal wave velocities were 1118 m/s and 5245 m/s,and the experimental transverse and longitudinal wave velocities were 1290 m/s and 5209 m/s,respectively.The amplitude attenuation and the time-domain waveforms were in good agreement when comparing the simulated and measured waveforms with the experimental waveforms.Therefore,the effects of viscoelasticity on Chinese fir specimens and the validity of the simulation model were confirmed.