頁籤選單縮合
題 名 | 柳杉正常木之生長應力分布=The Growth Stress Distribution of Planted Cryptomeria Japonica |
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作 者 | 黃彥三; 陳欣欣; 陳玉秀; | 書刊名 | 中華林學季刊 |
卷 期 | 31:2=121 1998.06[民87.06] |
頁 次 | 頁177-186 |
分類號 | 436.11 |
關鍵詞 | 生長應力; 解放應變; 表面應力; 應變片; Growth stress; Released strain; Surface stress; Strain gage; |
語 文 | 中文(Chinese) |
中文摘要 | 本試驗以林試所六龜分所柳杉造林木為對象,進行生長應力之測定,選取二株約40 年生之柳杉正常木,在胸高附近作環剝去皮,次將樹幹圓周分為6等分,各沿樹幹縱軸方向 與圓周方向貼上應變片,以鋸切法解放縱向與橫向應力。然後伐倒樹木並截斷成1.5公尺長 原木,每段原木在中央部份亦去皮後,同樣測定縱向與橫向生長應力,以瞭解樹高對生長應 力之影響。此外並取一段原木,留取通過髓心之徑面板,在不同位置(髓心距)及板側面貼 上應變片,用以測定縱斷面上的軸向應力分布。試驗結果顯示:生長應力隨樹高之增加並無 大變化,樹幹圓周之方位亦與生長應力無大關係。樹幹外周呈引張應力,靠近髓心則轉變為 壓縮應力,呈V型分布。樹幹邊材之彈性係數較大,靠髓心則較小。 |
英文摘要 | The annual addition of wood on the outside of tree trunks adds to the formation of growth stress. This accumulates yearly and is therefore regularly distributed along the longitudinal plane through the pith. Trees adjust its growth stress to satisfy its environment requirement and therefore maintain the physical need of the tree itself. However, growth stress may cause failure during wood utilization and lowers the value of wood products. The equilibrium state of the standing tree will release its growth stress during wood processing. As a result, logging and cutting may cause heart crack in wood, while sawing may cause warping. Therefore, it is necessary to understand the growth stress of trees and find proper methods for reducing it. In this study, planted Cryptomeria trees were used for measuring the surface strain at different heights and the strain on the diametral plank at breast height. The results obtained were as follows: 1. There was no variation in surface growth strain at different heights. 2. There was no variation in surface growth strain at different peripheral positions on the tree trunk. 3. The growth stress was tensile on the outer part of the tree trunk and compressive in the inner part, yielding a V-shaped stress distribution. |
本系統中英文摘要資訊取自各篇刊載內容。