基于小波变换的木材声发射驻波信号特征研究  

Research on Standing Wave Signal Characteristics of Wood Acoustic EmissionBased on Wavelet Transform

作　　者：罗蕊寒 方赛银[1] 丁锐 赖菲 杨洲凌 李明[2,3] 翟梦群 LUO Rui-han;FANG Sai-ying;DING Rui;LAI Fei;YANG Zhou-ling;LI Ming;ZHAI Meng-qun(College of Machinery and Transportation,Southwest Forestry University,Kunming 650224,Yunnan,China;Key Laboratory of Advanced Perception and Intelligent Control of High-end Equipment of Ministry of Education,Anhui Polytechnic University,Wuhu 241000,Anhui,China;School of Electrical Engineering,Anhui Polytechnic University,Wuhu 241000,Anhui,China;College of Mechanical Electronic Engineering,Northwest A&F University,Yangling 712100,Shaanxi,China)

机构地区：[1]西南林业大学机械与交通学院,云南昆明650224 [2]安徽工程大学高端装备先进感知与智能控制教育部重点实验室,安徽芜湖241000 [3]安徽工程大学电气工程学院,安徽芜湖241000 [4]西北农林科技大学机械与电子工程学院,陕西杨陵712100

出　　处：《西北林学院学报》2023年第3期194-202,共9页Journal of Northwest Forestry University

基　　金：国家自然科学基金(32160345,31760182)。

摘　　要：为研究木材损伤断裂时的声发射(AE)信号所激发的驻波信号特征与木材固有特性之间的关系,采用薄木条折断的方式产生AE源,在小波变换的基础上分析驻波频率,并计算纵波传播速率,依据弹性波理论计算出木材顺纹弹性模量(MOE)。首先,在2种不同长度的木材试件一端分别加工出8根80 mm×10 mm的薄木条,通过外加冲击力折断木条以产生AE源,通过放置在试件端面的2个传感器采集原始AE信号,采样频率设定为500 kHz。然后,根据驻波特性确定原始信号的驻波阶段,进而对该阶段AE信号进行4层小波分解,依据分解后信号的时频域特征析取驻波信号波形。最后,依据驻波产生原理计算纵波传播速率,并结合弹性波理论计算试件的MOE。结果表明,拉伸试验测得樟子松和榉木试件的MOE分别为9.30 GPa和11.63 GPa,800 mm樟子松和榉木试件通过驻波计算所得MOE分别为9.37 GPa和12.34 GPa,与实测MOE的误差分别为0.75%和5.24%;600 mm的樟子松和榉木试件通过驻波计算所得MOE分别为9.31 GPa和11.81 GPa,与实测MOE的误差分别为0.10%和1.55%。In order to study the relationship between the characteristics of standing wave signal excited by acoustic emission(AE)signal during wood damage and fracture and the inherent characteristics of wood,the AE source was generated by thin wood strip fracture.Based on the wavelet transform,the standing wave frequency was analyzed and the longitudinal wave propagation rate in the along grain direction was calculated,and then the along grain modulus of elastic(MOE)of wood was calculated according to the elastic wave theory.Firstly,8 thin wood strips with the size of 80 mm×10 mm were processed at one end of the specimens of two wood species(Pinus sylvestris var.mongolica and Zelkova schneideriana)with different lengths.During the test,an impact force was applied to cause the thin wood strips to break to generate AE sources,and the two sensors were placed on the ends of the specimen to collect the original AE signal,and the sampling frequency was set to 500 kHz.Secondly,the stage at which the standing wave in the AE signal occurred was determined according to the characteristics of the standing wave,and then a 4-layer wavelet decomposition was performed on the AE signal at this stage.The standing wave signal features were extracted according to the time-frequency domain characteristics of the decomposed signal.Finally,the longitudinal wave propagation rate was calculated according to the standing wave generation principle,and the MOE of the specimen was calculated combined with the elastic wave theory.The values of MOE of two wood species(P.sylvestris var.mongolica and Zelkova schneideriana)specimens measured by tensile test were 9.30 and 11.63 GPa respectively.The values of MOE of 800 mm specimens of two wood species calculated by standing wave were 9.37 and 12.34 GPa,with errors of 0.75%and 5.24%,respectively.The values of MOE of 600 mm specimens of two wood species calculated by standing wave were 9.31 and 11.81 GPa,with errors of 0.10%and 1.55%,respectively.

关 键 词：声发射 小波变换 驻波 时频域分析 顺纹弹性模量 

分 类 号：S781.38[农业科学—木材科学与技术]