應力波時間差法應用於材質評估之研究（I）

Feasibility of Evaluating Lumber and Tree Quality by Using Stress Wave Method (I)

莊世滋(Shih-Tzu Chuang) ； 王松永(Song-Yung Wang)

《林產工業》 16卷4期 (1997/12) Pp. 681-696

摘要

本研究目的係探討應力波非破壞性檢測應用於柳杉原木、鼓型試材及實大樑之材質可行性評估。其中Hammer打擊位置及應力波傳播路徑對於應力波速度之影響，並探究不同尺寸試材間之相關性。所得結果如下：1．應力波之再現性受原木直徑級之影響。2．原木之橫斷面、側邊及鼓型試材之端部與側邊，所測得經由hammer敲擊所產生之應力波波速，彼此間可由下列關係式表示:原木　V_(end) = 0.9904 V_t - 119.82鼓型試材　V_(end) =1.4786 V_t - 14453V_(end)係表示hammer敲擊端部所產生之應力波速V_t係表示由側邊所測得之應力波速3．原木、鼓型試材及實大樑三者問之應力波速，具有下列之直線關係存在：V_1=0.968 V_b - 62.5V_s=0.9224 V_b + 147.56V_1= 1.0382 V_s -182.55V_1，V_s及V_b分別代表原木、鼓型試材及實大樑之應力波速。4．位於邊材領域之實大樑所測得之應力波速度會明顯大於心材領域者；但兩者之動彈性係數則無明顯差異。

關鍵字

柳杉 ； 原木 ； 應力波計時儀 ； 應力波波速 ； 動彈性係數

並列摘要

This study was designed to investigate the effects of impacting position and direction of hammer on the stress wave velocity in logs, cant-shaped boards and large rectangular beams of Japanese cedar (Cryptomeria japonica D. Don.), and the correlations among above three difference configuration of specimens. The results are summarized as follows: 1. The reproducibility of stress wave is affected by log diameter. 2. The velocity of stress wave that were induced by hammer impacting on surface and ends of logs, and on edges and ends of cant-shaped boards could be represented by following linear regression formulas: logs; V_(end)=0.9904 V_t-119.82 cant-shaped boards; V_(end)=1.4786 V_t-14453 Vend represent the velocity of stress wave which was induced by impacting hammer on the end, and Vt represent that measured from side impaction. 3. Correlations among stress wave velocities in logs, cant-shaped boards and large rectangular beams could be represented by a highly linear regression formulas as follows: V_1 = 0.968 V_b - 62.5 V_s = 0.9224 V_b + 147.56 V_1= 1.0382 V_s - 182 . 55 V_1 , V_s and V_b represent respectively the stress wave velocity of logs, cantshaped boards and large rectangular beams. 4. The stress wave velocity in sapwood zone of large rectangular beams was significantly greater than those of heartwood section. However, significant differences not showed in their dynamic modulus of elasticity.

並列關鍵字

Japanese cedar ； log ； stress wave timer ； stress wave velocity ； dynamic modulus of elasticity