應力波非破壞測定法檢測木質板材之異方性

Detecting the Anisotropic Characteristics of Wood-Based Panels by Stress Wave NDT Methods

鐘建有(Jian-Yo Jung) ； 陳載永(Tsai-Yung Chen)

《林產工業》 15卷4期 (1996/12) Pp. 574-585

摘要

木質板材通常是由較小形之木質纖維狀物質、粒片、單板或木條等原料為組合元（Composite element），經膠合劑之膠合而形成之板狀材料。因此，製成之板材常會因不同材料排列方式，或分佈不均而產生異方性之現象，並進而造成板材性質之差異。本試驗是利用非破壞性測定法之應力波傳遞速度與縱向振動頻率，探討木質板材板面3個方向之差異性。使用之木質板材有合板、粒片板、中密度纖維板與定向粒片板等，分別以應力波計時儀與打音頻譜分析系統預測板材強度，再以破壞性方法驗證之。經比較非破壞性與破壞性方法測定之結果，可知合板與定向粒片板之板面具有明顯之異方性存在，合板之3個方向波速、縱向振動頻率與靜曲彈性係數，分別為板寬方向＞板長方向＞45°方向，而定向粒片板則為板長方向＞45°方向＞板寬方向，至於中密度纖維板與粒片板板面之異方性則不明顯。

關鍵字

波速 ； 縱向振動頻率 ； 木質板材 ； 異方性

並列摘要

Wood based panels were made from small size composite elements of wood fibers, particles, veneers or woods, and bounded with adhesives in usual. Panels properties changes when the alignment direction or distribution of thus materials changed. The NDT methods of wave velocity, and longitudinal vibration frequency were used in this study , in order to find out the property differences in three directions(∥, □, 45°) of panels. The samples such as, plywood, particleboard, medium density fiberboard and orientated strand board (OSB) were tested by using of NDT instruments, such as stress wave timer, tap tone frequency analysis system for their detailed dimensional variations. The MOE of three directions of panels were also detected by destructive methods. Test results indicated that the differences were significant among three directions of plywood and OSB. The values of wave velocity, longitudinal vibration frequency and MOE of three directions were found as the order of width direction ＞ length direction ＞45° direction for plywood, length direction ＞45° direction ＞ width direction for OSB. Anisotropic characteristics of particleboard and medium density fiberboard however, were found to be not significant.

並列關鍵字

wave velocity ； longitudinal vibration frequency ； wood based panels ； anisotropic characteristics