Mechanical response of wood perpendicular to grain when subjected to changes of humidity

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Mechanical response of wood perpendicular to grain when subjected to changes of humidity. / Svensson, Staffan; Toratti, Tomi.

I: Wood Science and Technology, Vol. 36, Nr. 2, 2002, s. 145-156.

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Svensson, Staffan ; Toratti, Tomi. / Mechanical response of wood perpendicular to grain when subjected to changes of humidity. I: Wood Science and Technology. 2002 ; Vol. 36, Nr. 2. s. 145-156.

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TY - JOUR

T1 - Mechanical response of wood perpendicular to grain when subjected to changes of humidity

AU - Svensson, Staffan

AU - Toratti, Tomi

PY - 2002

Y1 - 2002

N2 - This paper describes the deformations caused by stress and humidity interaction, mechano-sorption, in the cross grain directions of wood and the relaxation or accumulation of internal stresses caused by these deformations. Long-term tests on small clear specimens in cyclic climates with both tensile and compressive loads were carried out. The development of internal stresses in timber was measured indirectly at different times during the adsorption and desorption processes. Released deformations were measured from cross-sections after cutting them to small slices. These deformations were used to estimate the internal stresses caused by the humidity variations. Tests with constant loads and multiple humidity cycles show a mechano-sorptive strain that is ten times higher than the elastic strain. It is shown that existing models for describing mechano-sorption perpendicular to grain are inaccurate when applied to multiple humidity cycles. The present results demonstrate that if the mechano-sorptive behaviour and the moisture gradients in wood can be accurately described, it is possible to predict the stress distribution in a timber cross-section by knowing the climate history.

AB - This paper describes the deformations caused by stress and humidity interaction, mechano-sorption, in the cross grain directions of wood and the relaxation or accumulation of internal stresses caused by these deformations. Long-term tests on small clear specimens in cyclic climates with both tensile and compressive loads were carried out. The development of internal stresses in timber was measured indirectly at different times during the adsorption and desorption processes. Released deformations were measured from cross-sections after cutting them to small slices. These deformations were used to estimate the internal stresses caused by the humidity variations. Tests with constant loads and multiple humidity cycles show a mechano-sorptive strain that is ten times higher than the elastic strain. It is shown that existing models for describing mechano-sorption perpendicular to grain are inaccurate when applied to multiple humidity cycles. The present results demonstrate that if the mechano-sorptive behaviour and the moisture gradients in wood can be accurately described, it is possible to predict the stress distribution in a timber cross-section by knowing the climate history.

U2 - 10.1007/s00226-001-0130-4

DO - 10.1007/s00226-001-0130-4

M3 - Article

VL - 36

SP - 145

EP - 156

JO - Wood Science and Technology

JF - Wood Science and Technology

SN - 1432-5225

IS - 2

ER -