VARIATION OF MODULUS OF ELASTICITY IN THE TANGENTIAL DIRECTION WITH MOISTURE CONTENT AND TEMPERATURE FOR NORWAY SPRUCE (PICEA ABIES)

Mats Ekevad, Ann Axelsson

Abstract


Modulus of elasticity (MOE) in the tangential direction for Norway spruce, Picea abies (L.) H. Karst, was measured. Test samples were tested in three-point bending, and moisture content (MC) and temperature were varied between the green condition and 7% MC and between 20°C and 80°C, respectively. Using correction factors calculated from finite element simulations, an adjustment of measured MOE was made to the ideally tangential direction. The results show MOE and the gradients with respect to MC and temperature and how they vary with MC and temperature. The gradients are factors in gradient terms in the incremental stress-strain relation for linear elastic behaviour during load cycles where there are mechanical loads and at the same time, varying MC and temperature. The gradient terms add to the temperature and MC expansion coefficients and may be of significant size for cases with high stress, high temperature, and high MC.

Keywords


Wood; Elasticity; Shrinkage; Creep; Mechano-sorption

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