基于声-超声技术的木材弹性模量测定方法研究  

Wood elastic modulus determination based on acoustic-ultrasonic technique

作　　者：徐锋[1] 刘云飞[1] 潘惠新[2] 

机构地区：[1]南京林业大学信息科学技术学院,南京210037 [2]南京林业大学森林资源与环境学院,南京210037

出　　处：《振动与冲击》2014年第4期210-214,共5页Journal of Vibration and Shock

基　　金：国家公益项目(201004004);江苏高校优势学科建设工程一期项目(苏政办发2011-137-5);南京林业大学科技创新基金(163070080)

摘　　要：提取声信号基频是声-超声方法测定木材弹性模量的关键。由于噪声和传感器谐振频率等因素的影响，直接应用快速傅里叶变换（FFT）方法提取信号基频计算弹性模量通常比标准的力学方法大20％左右。基于此，提出应用最大公约数算法提取信号基频，构建一种测量木材弹性模量的改进方法，并给出此算法的详细步骤。应用该方法和FFT方法分别对杨树木芯样本进行测试，弹性模量Eu和Ef的计算值范围分别为8．23～40．32 GPa和7．94～51．87 GPa，对比标准力学方法（弹性模量Es测量值为6．72～36．35 GPa），误差下降了约10％。进一步分析Eu -Es和Ef-Es的相关性，相关系数分别为0．94和0．86，都呈显著相关。实测数据表明，应用本文方法计算所得的木材弹性模量与力学方法测试的数值更加吻合，相关性更好。Fundamental frequency extraction of an acoustic signal is a key step for determination of elastic modulus of wood with the acoustic-ultrasonic technique.An elastic modulus calculated with the fundamental frequency of a sound signal extracted using the existing fast Fourier transformation （FFT）method is about 20%bigger than that acquired with the standard mechanical method due to noise and sensor resonant frequencies and other factors.Here,the largest common divisor algorithm was proposed for extraction of fundamental frequency to construct an improved method to measure elastic modulus of wood,and the detailed process of extracting the fundamental frequency was presented.The poplar core samples were tested by using the proposed method and the FFT method respectively.It was indicated that the calculated values of elastic modulus（Eu）determined with the proposed method,and the calculated ones of elastic modulus（Ef） determined with FFT method are in the range of 8.23-40.32 GPa and 7.94-51.87 GPa,respectively;comparing them with the measured value of static elasticity modulus （Es）within the range of 6.72 GPa to 36.35 GPa determined with the standard method of mechanics,the error of the former is 10% smaller than that of the latter;linear correlations were analyzed,the correlation coefficient between Eu and Es is 0.94,and the correlation one between Efand Es is 0.86,both of them reveal significant correlations;so,the tested data show the proposed method is better than the FFT method for measuring wood elastic modulus.

关 键 词：声-超声 弹性模量 最大公约数算法 基频提取 

分 类 号：TB529[理学—物理]