木材模拟声发射源的产生与特性  

Generation and Characteristics of Simulated Acoustic Emission Source of Wood

作　　者：王明华 邓婷婷[2] 方塞银 李晓崧 赖菲 李明[1] Wang Minghua;Deng Tingting;Fang Saiyin;Li Xiaosong;Lai Fei;Li Ming(Southwest Forestry University,Kunming 650224,P.R.China)

机构地区：[1]西南林业大学机械与交通学院,云南650224 [2]西南林业大学,云南650224

出　　处：《东北林业大学学报》2021年第6期96-101,118,共7页Journal of Northeast Forestry University

基　　金：国家自然科学基金项目(31760182);云南省教育厅科学研究基金项目(2021Y224,2021J0156,2021J0158)。

摘　　要：针对如何人为模拟木材损伤声发射(AE)源信号问题,采用折断铅芯、薄木条2种方式分别在樟子松、榉木试件中产生模拟AE源。通过小波处理、信号相关性分析,研究不同模拟AE源的信号特征和传播速度。其中折断铅芯试验依照ASTM-E976标准;折断薄木条产生模拟AE信号试验是在试件端面施加冲击力,引起断裂,以模拟木材发生点断裂时产生的AE信号。所有试验的AE信号采样频率均设定为500 kHz。依据木材AE信号的频率范围,采用5层小波分析的方法重构AE信号波形,进而分析2种模拟AE源信号的频率组成与分布。最后,采用两点时差定位法计算2种AE信号在试件顺纹理方向的传播速率。结果表明:2种方式产生的AE信号的频率组成和分布没有明显差异。折断樟子松、榉木试件端面薄木条产生的AE信号在断裂初期、断裂阶段的平均传播速度分别为786.5、1085.1 m·s^(-1)和1145.2、1557.6 m·s^(-1);折断铅芯时,AE信号在樟子松、榉木试件中的平均传播速度分别为760.9、1120.5 m·s^(-1)。折断铅芯产生的模拟AE源能够较好地反映木材在特定损伤阶段产生的AE信号频率特征,但在研究木材AE信号传播规律时,折断薄木条试验方法更为客观。Aiming at the problem of how to artificially simulate the acoustic emission(AE)source signal of wood damage,the AE sources were generated in the Pinus sylvestris var.mongolica and Zelkova schneideriana by breaking lead core and thin wood strips,respectively,and the signal characteristics and propagation velocity of different simulated AE sources were studied through the wavelet processing and signal correlation analysis.The lead core fracture test was conducted in accordance with ASTM-E976 standard,the thin wood strip fracture generated a simulated AE signal by applying an impact force to the end face of the specimen,thereby causing fracture to simulate the AE signal generated when a point fracture occured in the wood.The AE signals sampling frequency of all tests was set at 500 kHz.Secondly,according to the frequency range of AE signals of wood,the AE signal waveform was reconstructed by using the 5-level wavelet analysis,and then the frequency composition and distribution of the two simulated AE source signals were analyzed.Finally,the two-point time difference location method was used to calculate the propagation velocity of the two AE signals along the texture direction of the specimen.The results showed that there was no significant difference in the frequency composition and distribution of AE signals generated by the two methods.The average propagation velocity of AE signals generated by breaking thin wood strip of P.sylvestris var.mongolica and Z.schneideriana were 786.5,1085.1 and 1145.2,and 1557.6 m/s at the early and initial and fracture stages,respectively,while that of lead core were 760.9 and 1120.5 m/s.Therefore,the simulated AE source generated by breaking lead core can well reflect the AE signal frequency characteristics generated in specific damage stage of the wood;However,when studying the law of AE signal propagation of wood,the test method of breaking thin wood strips is more objective.

关 键 词：模拟AE源 木材 小波分析 信号特性 

分 类 号：TN911.7[电子电信—通信与信息系统]