應用AE評估省產造林木之靜曲強度

本研究之目的為應用AE評估省產造林木之靜曲強度，將台灣杉、杉木與紅檜等3種省產造林木鋸製成板材並經氣乾後，分別製成3×3×50cm之無節材、有節材及含心材等3種材別，靜曲試驗探用中央集中載重並同時檢測AE之發生。由試驗結果得知同一樹種中之MOR與MOE均以無節材最大，含心材次之，有節材最小，除了台灣杉含心材之外，各種試材之MOR與MOE之間均有正相關關係存在。同樹種之有節材均分別較無節材與含心材，在較低載重時即有較多之AE發生。AE最大振幅分佈明顯地受節的影響，各樹種之有節材於試驗時產生較多振幅較大之AE。對任何樹種與材別而言，在靜曲試驗之比例限度內，AE事件總數達一定值時之載重與MOR之間存在直線關係，顯示可由靜曲試驗初期之AE發生狀況評估MOR。

關鍵字

音射；音射事件；造林木；靜曲強度；靜曲彈性係數

並列摘要

The purpose of this study is to estimate the static bending strength of wood from domestic plantation forests by utilizing the acoustic emission (AE) technique. Taiwania (Taiwania cryptomerioides), China fir (Cunninghamia lanceotata), and Taiwan red cypress (Chamaecyparis formosensis) were harvested from man-made forests, then sawed into boards. After air drying, boards were cut into 3cm×3cm×50cm specimens and classified into clear wood, knotted wood or boxed heart wood for the investigation. Specimens were subjected to the third-point bending test. Both the bending strength and AE events were determined. In all species, clear wood had the largest MOR (modulus of rupture) and MOR (modulus of elasticity); boxed heart wood was next and knotted wood had the smallest values. In all tests, except those of boxed heart wood of Taiwania, there were good correlations between MOR and MOE. At a lower loading, knotted wood generated more AE events than either clear wood or boxed heart wood for the same species; the AE peak amplitudes were affected by knots in the wood. Tests of knotted wood resulted in more AE events with larger amplitudes for each species. Within the proportional limit, a good correlation existed between MOR and load when AE events reached a certain value for all specimens. It was possible, therefore, to estimate the MOR by the AE parameter in the early stage of the bending test.

並列關鍵字

acoustic emission ； AE event ； plantation wood ； modulus of rupture ； modulus of elasticity

國際替代計量

應用AE評估省產造林木之靜曲強度

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