Mechanics of Time-Dependent Materials

, Volume 9, Issue 2–3, pp 161–172 | Cite as

Viscoplasticity of Steamed Wood



Plasticity of steamed Spruce wood, compressed in uniaxial strain, is addressed in terms of a classical linear viscoplasticity model. The dynamic stiffness modulus increases along with compressive stress in the radial material direction, but decreases as a function of stress in the longitudinal direction. The longitudinal viscoplastic retardation time is an order of magnitude smaller than the radial retardation time, the plastic strain rate at invariant normalized overstress thus being much higher in the longitudinal direction. In the longitudinal direction, the retardation time increases along with increased compressive stress. The viscoplastic retardation time is inversely proportional to the straining rate in both material directions. Consequently, within any particular schedule of normalized overstress, the accumulation of plastic strain along with the number of loading cycles is independent of straining rate.

Key Words

dynamic stiffness retardation time strain rate loading frequency Picea Abies 


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© Springer Science + Business Media, Inc. 2005

Authors and Affiliations

  1. 1.Faculty of ForestryUniversity of JoensuuJoensuu

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