A. Hanhijärvi, P. Helnwein, A. Ranta-Maunus:
"Two-Dimensional Material Model for Structural Analysis of Drying Wood as Viscoelastic-Mechanosorptive-Plastic Material";
in: "3rd Workshop on Softwood Drying to Specific End-Uses, VTT Building and Transport/COST Action E 15, Advances in the Drying of Wood (1999-2003)", COST (European Cooperation in the Field of Scientific and Technical Research), Espoo, Finland, 2001, Paper ID 14.
The paper introduces a model for the stress analysis of drying wood in the transverse (RT) plane. The model is based on an earlier uniaxial development by Hanhijärvi in 1998-2000. The novel features are the two-dimensional extension, and the description of partially irrecoverable mechanosorptive strain by introducing a plastic element. Thus it defines the mechanical behavior of drying wood as a viscoelastic-mechanosorptive-plastic one. Moreover, the mechanical description of the constitutive equations has been consistently reformulated on a thermodynamic basis.The model is applicable over a wide range of temperature as well as moisture content (20 C - 120 C; nearly 0 % moisture content till fiber saturation), which is achieved through applying the time-temperature-moisture equivalence principle to the evolution laws for viscoelastic strain. This principle and a moisture-change-temperature equivalence principle is applied to mechanosorptive creep in order to take into account its dependence on temperature. Mechanosorptive creep is assumed to be absent in shear.
Keywords: wood, 2d, drying, mechano-sorption, multiaxial, plastic, viscoelastic