School of Machinery and Transportation, Southwest Forestry University, Kunming 650224, China.
Key Laboratory of Advanced Perception and Intelligent Control of High-End Equipment of Ministry of Education, Anhui Polytechnic University, Wuhu 241000, China.
Sensors (Basel). 2022 Aug 11;22(16):5991. doi: 10.3390/s22165991.
To study the effect of frequency on the attenuation characteristics of acoustic emission signals in wood, in this paper, two types of hard wood and soft wood were studied separately, and the energy attenuation model of the propagation process of AE sources with different frequencies was established. First, using the piezoelectric inverse effect of the AE sensor, an arbitrary waveform generator was used to generate frequency-tunable pulses in the range of 1 kHz to 150 kHz as the AE source, where the AE source energy could be regulated by the output voltage level. Then, five AE sensors were placed at equal intervals of 100 mm on the surface of the specimen to collect AE signals, and the sampling frequency was set to 500 kHz. Finally, the energy value of AE signal of each sensor was calculated based on the AC principle, and the energy attenuation model was established by exponential fitting. The results showed that both the amplitude and energy of the AE signals of different frequencies showed negative exponential decay with the increase of propagation distance, and, at the same frequency, the change of AE source energy level had no significant effect on its attenuation rate. Compared with hard wood, the energy attenuation of the AE signal of soft wood was more sensitive to the change of frequency, and, at the same frequency, the attenuation rate of soft wood was smaller than that of hard wood.
为了研究频率对木材声发射信号衰减特性的影响，本文分别对两种硬木和软木进行了研究，并建立了不同频率声发射源传播过程中能量衰减模型。首先，利用声发射传感器的压电逆效应，采用任意波形发生器产生频率可调的 1 kHz 至 150 kHz 范围内的脉冲作为声发射源，其中声发射源能量可通过输出电压电平进行调节。然后，在试件表面等间距放置五个声发射传感器，采集声发射信号，采样频率设置为 500 kHz。最后，根据交流原理计算每个传感器的声发射信号能量值，并通过指数拟合建立能量衰减模型。结果表明，不同频率的声发射信号的幅度和能量均随传播距离的增加呈负指数衰减，且在同一频率下，声发射源能量水平的变化对其衰减率没有显著影响。与硬木相比，声发射信号的能量衰减对频率变化更为敏感，且在同一频率下，软木的衰减率小于硬木。
