Identification of defects of wood by using wave analysis of tap tone and application to machine stress rating of lumber

利用敲击声波分析识别木材缺陷及其在木材机械应力评级中的应用

• 批准号: 12660148
• 负责人: SOBUE Nobuo
• 金额: $ 2.05万
• 依托单位: Shizuoka University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2000
• 资助国家: 日本
• 起止时间: 2000 至 2001
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-12660148/
• 关键词: Wood defects; Tap tone; Wave analysis; Identification of defets; Power spectrum; Logarithmic decrement; Stress rating; 位置予測; 数値解法; フーリエ変換

Identification of defects in lumber by a wave analysis of tap tone and application to a machine stress rating of lumber were studied.1. Identification of defects by a wave analysis.A transfer matrix method was used to evaluate the spectrum peak shift due to defects of a specimen. A numerical equation which estimates the spectrum peak shift by defects was obtained. Experiments by using specimens having round holes showed the same tendency as the numerical simulation of the transfer matrix method. The peak shifts of the specimen having multiple holes were evaluated by a linear combination of the effect of individual hole. A new principle to identify the defects positions was proposed. The position was identified so that the coincidence between experimental and estimated values becomes maximum.2. Determination of vibration parameters by a wave analysisA tap tone includes useful information not only in a fundamental vibration but also in higher order vibration waves. Isolation of the wave of an individual mode was done by using the filtering procedure of Fourier transformation. Then Hilbert transformation was adopted to obtain a time envelope and logarithmic decrement was determined. Moreover, an instantaneous frequency given by Hilbert transformation showed a potential of a quasi time-frequency simultaneous analysis of a tap tone.3. Application of wave information to machine stress rating of lumberSmall and full size wood specimens were used. A multiple regression analysis using Young's modulus, logarithmic decrement and irregularity in frequencies of higher ordered vibrations gave higher correlation than the case of a simple regression which used Young's moduli

研究了敲击音波形分析识别木材缺陷及其在木材机械应力评级中的应用。 1．通过波分析识别缺陷。使用传递矩阵方法来评估由于样本缺陷引起的光谱峰值偏移。获得了估计缺陷引起的光谱峰值偏移的数值方程。使用具有圆孔的样本进行的实验显示出与传递矩阵法的数值模拟相同的趋势。通过单个孔的影响的线性组合来评估具有多个孔的样本的峰移。提出了一种识别缺陷位置的新原则。确定位置以使实验值与估计值之间的重合度最大。 2．通过波分析确定振动参数敲击音不仅包括基本振动中的有用信息，还包括高阶振动波中的有用信息。单个模式的波的隔离是通过使用傅立叶变换的滤波过程来完成的。然后采用希尔伯特变换获得时间包络并确定对数减量。此外，Hilbert变换给出的瞬时频率显示了敲击音准时频同时分析的潜力。 3．波信息在木材机械应力评级中的应用使用了小型和全尺寸木材样本。使用杨氏模量、对数递减和高阶振动频率不规则性的多元回归分析比使用杨氏模量的简单回归具有更高的相关性