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| 題 名 | 音射應用在木材靜曲試驗=Application of Acoustic Emission in Wood Static Bending |
|---|---|
| 作 者 | 李世豪; | 書刊名 | 中華林學季刊 |
| 卷 期 | 32:3=126 1999.09[民88.09] |
| 頁 次 | 頁401-407 |
| 分類號 | 436.187 |
| 關鍵詞 | 音射; 靜曲試驗; 最大載重; 撓曲度; AE累計次數值; Acoustic emission; Bending test; Maximum load; AE cumulative events; Deflection; |
| 語 文 | 中文(Chinese) |
| 中文摘要 | 木材若作為樑結構用材,當載重時,無論發生微細或巨觀破壞,都會有音射訊號(Acoustic Emission)--簡稱AE--之伴隨,因此,若能使用AE檢測科技監測樑載重時,從微細裂痕發生、成長、傳播至全破壞過程,即可從AE訊號譜中,瞭解樑載重至何種階段,並在樑未全破壞前,發出警訊,即時作好逃生之準備,以避免人員傷亡。 本研究係探討:(1)樹種、破壞沿伸系統及缺痕深對最大載重、撓曲度與AE累計次數之影響。(2)最大載重、撓曲度與AE累計次數彼此之相關性。(3)是否能使用 AE特徵值,來預測相對應木材強度及載重破壞階段。 本試驗是以紅櫟木與雲杉為材料,經鉋整並製成無缺痕與單邊有缺痕模態(Ⅰ)試片。以萬能試驗機靜曲試驗暨 AE 系統搜集最大載重、撓曲度與AE值。 試驗主要結果如下:(1)最大載重受樹種及缺痕深之影響,不受破壞沿伸系統之影響。(2)AE累計次數與最大載重相關性極顯著,與撓曲度相關性不顯著。(3)AE累計次數之變異係數過高,因此AE累計次數不適宜預測木材強度。(4)單位時間AE出現次數可粗略劃分三種木材載重破壞階段。 |
| 英文摘要 | When wood is used as beam structure and loaded, acoustic emission (AE) will accompany with either micro or macro fracture. Therefore, AE can be applied to monitor the process of crack occurrence from its devlopment, propagation to total failure. The loss of life can also be avoided from noticing warnning alarms. The objectives of this study were to find out (1) the effects of species, crack propagation system and crack length on maximum load, deflection and AE cumulative events, (2)the relationships among maximum load, deflection and AE cumulative events, (3) the possibility of predicting wood strength and the phase of fracture by the characteristics of AE. The materials examined were red oaks and spruces. Specimens of opening mode (Mode I) with single edge notch and without notch were made and tested by static bending. The maximum load, deflection and AE cumulative events were recorded and measured. I found: (1) The maximum load was influenced by species and crack length significantly, but was not influenced by crack propagation system. (2) The relationship between AE cumulative events and the maximum load was significant, but the relation between AE cumulative events and the maximum load maximum load was significant, but the relation between AE cumulative events and the maximum load was not significant. (3) The variation coefficient of AE cumulative events was too high to predict wood strength. (4) The phase of wood fracture might be predicted by E frequency. |
本系統中英文摘要資訊取自各篇刊載內容。