Mechano sorptive behaviour of notched beams in bending

Signe Kamp Jensen, Preben Hoffmeyer

    Research output: Chapter in Book/Report/Conference proceedingArticle in proceedingsResearchpeer-review

    Abstract

    Short term bending tests with end-notched beams at constant or varying moisture content have shown an apparent contradictory dependency between moisture content and strength. The higher the moisture content the higher the strength. Varying moisture results in particularly significant differences.In order to study this phenomenon, moisture content and deformations perpendicular to grain were monitored at a stepwise changing humidity (55%, 90% RH at 20 degrees C). The normal stresses perpendicular to grain due to restricted swelling were then obtained by assuming Hooke's law applies and by neglecting deformation due to shear. Compression stresses perpendicular to grain in excess of 6 MPa were found in the vicinity of the notch following a period of adsorption. Similarly, small tension stresses of the order 1 MPa were registered in this area when the specimens were at their most dry condition.It thus seems that the unexpected increase in strength due to moisture uptake may in part be explained by the built-up of compression stresses perpendicular to grain caused by the moisture induced restricted swelling. Such compression stresses act as a reinforcement which must first be overcome before a tension perpendicular to grain failure can develop and ultimately lead to failure.
    Original languageEnglish
    Title of host publicationProceedings of the 1996 International Conference on Wood Mechanics
    Place of PublicationStuttgart
    PublisherFMPA-Otto-Graf-Institut
    Publication date1996
    Publication statusPublished - 1996
    Event1996 International Conference on Wood Mechanics - Stuttgart, Germany
    Duration: 14 May 199616 May 1996

    Conference

    Conference1996 International Conference on Wood Mechanics
    CountryGermany
    CityStuttgart
    Period14/05/199616/05/1996

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