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Bending creep behavior of wood under cyclic moisture changes

Abstract

This study examined the bending creep behavior in the longitudinal direction of six species under cyclic moisture content (MC) changes. For each species, tests were made at 20°C with five cyclic relative humidity changes between 65% and 95%, beginning from moisture adsorption. A load corresponding to 25% of short-term breaking load of the species was applied to the radial section of each specimen with four-point bending. The effect of MC change on instantaneous compliance was also investigated under the same condition. The quantitative relation between mechano-sorptive (MS) compliance and MC change was examined, and the material parameter KM for the relation in specific sorption was determined. Results indicated that the total compliance in the six species with different behavior increases with sorption time. As an integral part of total compliance, instantaneous compliance changes linearly with MC and influences to a greater or lesser extent the total compliance behavior. In general, with increasing MC change, the MS compliance linearly increases during the first adsorption and all desorption and decreases slightly during subsequent adsorption. The material parameterK M varies markedly not only with species but also with specific sorption. The first adsorption causes the largest deformation, followed by desorption.

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Correspondence to Yaguang Zhou.

Additional information

This paper was presented at the 48th annual meeting of the Japan Wood Research Society in Shizuoka, Japan. April 1998

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Zhou, Y., Fushitani, M., Kubo, T. et al. Bending creep behavior of wood under cyclic moisture changes. J Wood Sci 45, 113–119 (1999). https://doi.org/10.1007/BF01192327

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Key words

  • Creep
  • Cyclic moisture sorption
  • Bending stress
  • Species