Time dependence of Poisson's effect in wood II: Volume change during uniaxial tensile creep

Abstract

To determine the viscoelasticity of wood three-dimensionally, a longitudinal tensile creep test was conducted on 12 species of wood to examine the change in the rate of volume increase (ΔV/V) with time. Immediately after the beginning of creep, ΔV/V was positive, and during creep, ΔV/V decreased rapidly, then more gradually. The decrease in tangential strain was considered to mainly contribute to the decrease in ΔV/V during creep. Immediately after the removal of the load, ΔV/V decreased to a negative value; thereafter, it decreased slowly and finally reached a certain value. The value of ΔV/V during creep tended to decrease with increasing density of wood. Also, there was a negative correlation between wood density and the rate of increase in ΔV/V. © 2010 The Japan Wood Research Society.