木材含水率對應力波傳遞速度與振動頻率之影響Ⅱ

Effect of Moisture Content of Wood on the Wave Velocity and Vibration Frequency II

陳載永(Tsai-Yung Chen) ； 葉政翰(Jeng-Hann Yen) ； 鍾建有(Jian-Yo Jung)

《林產工業》 15卷3期 (1996/09) Pp. 415-424

https://doi.org/10.6561/FPI.1996.15(3).3

摘要

在諸多影響木材應力波非破壞性檢測之因素中，木材含水率之影響是屬重要因素之一。因此，探討試材含水率變化，對應力波傳遞速度與縱向振動頻率之影響，是本研究之重點。本試驗所選用之非破壞性測定裝置有：應力波計時儀、振動頻率測定器與打音頻譜分析系統，分別對不同含水率之杉木、美國西部鐵杉、冰片樹，以及橡膠木進行試驗。並以迴歸分析分別求出波速、縱向振動頻率與含水率之相關性，其結果呈現波速、縱向振動頻率均與試片含水率呈負相關，尤以含水率在纖維飽和點以下時更明顯，其中以橡膠木之線性迴歸分析結果最佳，其判定係數R^2值最大，於應力波計時儀者，其R^2值=0.93；打音頻譜分析系統R^2=0.91；振動頻率測定器R^2=0.83。而3種儀器中，則以應力波計時儀最適用於木材含水率之檢測。

關鍵字

應力波非破壞性測定 ； 波速 ； 縱向振動頻率 ； 含水率

並列摘要

Many factors of affect the stress wave nondestructive testing (NDT), among them the moisture content (MC) is one of the most important factor. Thus, to research the effect of wood MC on the wave velocity and longitudinal vibration frequency, which is the main purpose of this study. Test instruments such as: Stress Wave Timer (SWT), Vibration Frequency Tester (VFT), and Tap Tone Frequency Analysis System (TTAS) were used to detecting the effect of different MC of China fir, American hemlock, Kapur and Rubber wood on their tested results. Meanwhile, to indicate the relationship between longitudinal vibration frequency, wave velocity and MC by using the analysis of regression. The results showed negative correlation between wave velocity, longitudinal vibration frequency, and MC of samples, especially when the MC of samples was lower than F.S.P. . The results also indicated that the liner regression of Rubber wood was the best, in which, the determination coefficient R^2 =0.93 by SWT, 0.91 by TTAS, and 0.83 by VFT, and the most appropriate instrument for detect MC of wood was SWT.

並列關鍵字

Stress-wave NDT ； Wave velocity ； Longitudinal vibration frequency ； MC