1991 Fiscal Year Final Research Report Summary
Studies on Mechanism of Creep of Wood under Changing Moisture Content Conditions and Methods for Reducing its Creep
| Project/Area Number |
02660168
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
林産学
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| Research Institution | Tokyo University of Agriculture and Technology |
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Principal Investigator |
FUSHITANI Masami Tokyo University of Agriculture and Technology, Agriculture, Professor, 農学部, 教授 (80014950)
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| Co-Investigator(Kenkyū-buntansha) |
SATO Keiichi Tokyo university of Agriculture and Technology, Agriculture, Assistant Professor, 農学部, 助手 (90178723)
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| Project Period (FY) |
1990 – 1991
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| Keywords | wood / changing moisture content conditions / creep / stress dependence / acoustic emission / laminated wood / acetylating treatment |
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| Research Abstract |
1. We investigated the stress dependence of bending creep of wood under changing moisture content conditions and the acoustic emission(AE)generated during its creep process. In the exponential regression equation between the change in moisture content and the creep strain, the fitted values of exponent increased with increasing stress level under moisture-regain condition, whereas they are somewhat more than 1 and independent of stress level under moisture-loss condition. AEs generally were generated beyond the stress level within which creep strain was proportional to the applied stress. Under air-dry and moisture-regain conditions, AEs were generated above a stress level of 50 while under high moisture content and moisture-loss conditions, they were done above a stress level of 35 %. When creeprupture occurred, many AEs were generated immediately or for a short time before specimen was-ruptured.
2. We investigated the reducing effect of acetylating treatment on the bending creep of laminated wood under changing moisture content conditions in connection with the layers composed of acetylated laminae. The creep of laminated wood with acetylated laminae in compression side and tension side layers was smaller than that of laminated wood composed only of untreated laminae under moisture-regain and moisture-loss conditions. The laminated wood with the acetylated lamina in tension side layer showed the largest creep under moisture-regain and moisture-loss conditions, whereas the laminated wood with the acetylated lamina in compression side layer had the smallest creep under moisture-loss condition, and had a little more creep than the laminated wood only with untreated laminae under moisture-regain condition. This phenomenon can be explained in terms of both the warps due to the differences in shrinkage and swelling between the acetylated and the untreated laminae and the differences in compressive and tensile creeps between them.
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