Analysis of creep of wood during water adsorption based on the excitation-response theory

Abstract

The creep behavior of wood during water adsorption was mathematically analyzed based on the excitation-response theory. The creep change Φu(t), obtained by subtracting an instantaneous compliance Ju(0) from a creep compliance Ju(t), was linear in terms of moisture content at a steady state of moisture and was separable into two functions of time and moisture content. The creep compliance, however, was nonlinear. The creep change during water adsorption was obtained by applying the excitation-response theory to the creep change in a steady state of moisture. The equation was formally equal to the results reported so far. By using the derived equations, it was theoretically proved that the change in creep compliance during water adsorption from moisture content u0 to u1 is always greater than the difference between creep compliance at u0 and that at u1 in the steady state. © The Japan Wood Research Society 1999.