Mechano-Sorptive Deformation of Douglas-fir Specimens Under Tangential Tensile Stress During Moisture Adsorption

Qinglin Wu, Michael R. Milota

Abstract


Small specimens (3.2-mm thick) of Douglas-fir heartwood were tested for mechano-sorptive (MS) deformation in tangential tension during moisture adsorption. Tests were made at 65.5° with moisture content (MC) changing from 5 to 20% under four levels of stress: 0.276, 0.552, 0.827, and 1.24 MPa. The results confirmed that a large MS deformation occurs during the first MC increase after the load is applied. In a sorplion history of matched loaded and load-free specimens, the MS strain was shown to be proportional to applied stress, and the material parameters describing the interaction of stress and moisture change were independent of stress level.

Keywords


Softwood;strain;swelling;tension;wetting

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