A Theoretical Description of Creep Behavior During Water Desorption

Abstract

On the basis of a generalized Voigt model, a general formulation of creep behavior during water desorption is theoretically examined by use of the hole theory of Eyring (Halsey et al. 1945 ; Halsey and Eyring 1945 ; Eyring and Halsey 1946). The viscosity considering water desorption is represented by η(t)=η e /(1+nF(t)), where η(t) is the viscosity during water desorption, η e is the viscosity in the steady state of moisture, n is constant, F(t) is the rate of water desorption. By using of this viscosity, the equation for the creep during water desorption can represent the creep behavior in both the water desorption process and a steady state of moisture for wood. The equation is approximately represented by J(t)=J 0 (t)+KM(t), where J(t) is the creep compliance during water desorption, J 0 (t) is the creep compliance in a steady state of moisture, K is constant, M(t) is moisture change. The equation is found to be equivalent to the equations based on a Maxwell model which have satisfied empirical results so far.