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


  • Qinglin Wu
  • Michael R. Milota


Softwood, strain, swelling, tension, wetting


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.


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