木材壓縮試驗時試體表面溫度之變化

Changes in Surface Temperature of Wood Specimens during Compression Testing

黃國雄(Gwo-Shyong Hwang) ； 熊如珍(Ju-Chen Hsiung) ； 郭美吟(Mei-Yin Kuo)

《台灣林業科學》 16卷2期 (2001/06) Pp. 125-132

https://doi.org/10.7075/TJFS.200106.0125

摘要

本研究計畫旨在探討紅外線熱像儀應用於木材非破壞試驗之可行性，即木材受外力產生變形時，由其表面溫度之變化檢測其缺點或破壞位置。試驗中採用杉木、扁柏、肖楠、泡桐、柳桉與樺木等六樹種為試材。參照CNS 453木材壓縮試驗法進行縱向壓縮試驗與橫向壓縮試驗，使用紅外線熱像儀測定試體表面溫度之變化，由試驗結果檢討試體之壓縮變形、破壞與溫度上升之關係。
由縱向壓縮試驗六種試材之破壞情形與其熱像得知試體破壞位置與試體表面溫度上升之位置一致，顯示木材於縱向壓縮試驗中，當試體破壞時將所儲存之能量釋放出而使其破壞位置之表面溫度明顯上升，當在比例限度以下時，試體表面最高溫度幾乎沒有上升，而在比例限度以上接近最大載重，其表面最高溫度僅略上升0.3-0.4℃，隨著應變之增加，試體之表面最高溫度則隨應變之增大而明顯上升，當試體破壞即載重下降之瞬間，其表面最高溫度上升至最大。在試驗中表面最高溫度之上升程度依樹種而不同，如樺木之表面最高溫度上升了14.9℃，而扁柏則上升了7.9℃。
在橫向壓縮試驗中，應力於比例限度以下時試體表面最高溫度無明顯上升，而應力於比例限度以上時試體表面最高溫度則隨應變之增加而增大，但其增大之程度較縱向壓縮者明顯減小，僅約為1℃且受樹種之影響較不顯著。

關鍵字

紅外線熱像儀 ； 熱像 ； 表面溫度 ； 壓縮試驗

並列摘要

The objective of this project was to investigate the feasibility of usinginfrared thermography in nondestructive evaluation of wood defects or failure. The surface temperature of wood specimens of China fir (Cunninghamia lanceolata), Taiwan hinoki (Chamaecyparis taiwanensis), Taiwan incense cedar (Libocedra formosana), Taiwan paulownia (Paulownia taiwaniana), red meranti (Shorea spp.), and Taiwan zelkova (Zelkova serrata) under longitudinal and lateral compression loading was measured with a thermographic device. The relationships between the compression strain and fracture of the specimen, and the temperature rise are discussed.
In the longitudinal compression test, the location of the surface temperature rise closely corresponded with the site of fracture of the specimen. The temperature on the surface of a specimen remained almost unchanged below the proportional limit and rose only about 0.3-0.4℃ from that time until near the maximum load. An obvious increase in temperature occurred with a further increase in the compression strain accompanied by a decrease in load. The highest temperature was detected at the instant that the specimen failed. The temperature rises observed in this study differed with the species of wood tested; for example, 14.9 and 7.9℃ increases were detected for Taiwan zelkova and Taiwan hinoki, respectively.
In the test of lateral compression, the temperature rise on the surface of the wood specimen was not significant within the proportional limit but increased significantly with increasing compression strain above the proportional limit. The temperature rises were not significantly affected by the species of wood and were about 1℃ which were smaller than those observed in the longitudinal compression test.

並列關鍵字

infrared thermography ； thermal image ； surface temperature ； compression test