Constitutive equation of wood at variable humidity and temperature

Z. P. Bažant*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

73 Scopus citations


Theoretical analysis of the effects of variations in moisture content and temperature on the creep of wood is presented. Thermodynamics of the processes of diffusion of water in wood microstructure is discussed and distinction is drawn between macrodiffusion and microdiffusion. The constitutive relation for steady states of moisture content and temperature is formulated on the basis of Maxwell chain model whose viscosity coefficients depend on moisture content and temperature. It is shown that the apparent acceleration of creep due to simultaneous drying (or wetting) as well as heating (or cooling) may be modeled as additional, stress-induced shrinkage (or swelling) and stress-induced thermal expansion (or contraction), described by shrinkage and thermal expansion coefficients that depend on the absolute values of the rates of pore humidity and temperature. Certain other sources of irreversibility of creep are also discussed.

Original languageEnglish (US)
Pages (from-to)159-177
Number of pages19
JournalWood Science and Technology
Issue number2
StatePublished - Jun 1985

ASJC Scopus subject areas

  • Forestry
  • Materials Science(all)
  • Plant Science
  • Industrial and Manufacturing Engineering


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