Summary of mechano-sorptive research at the University of Minnesota, USA

The author provides a summary of mechano-sorptive research conducted at Kaufert Laboratory, University of Minnesota, USA. The intent is to provide research results and experimental techniques in an integrated manner that might be: of interest and possible use to others doing research in this area. A major conclusion for the author is that the mechano-sorptive behavior of wood stressed in compression is the dominant force in problems such as collapse in lumber drying and the: long term creep of wood structural members subjected to bending. Thr elimination of collapse in susceptible species such as California redwood, by use of a prefreezing treatment, is credited to the ability of prefreezing to increase the cells resistance to the perpendicular-to-grain compressive stress attributable to restrained shrinkage. In flexural tests with redwood, prefreezing reduced the deflection of beans dried under load by the same percentage as for the shrinkage of boards in kiln drying. When samples loaded in compression perpendicular to the grain were cycled in moisture content, the resulting deflection curve was identical to that obtained for beams cycled in moisture content. In each case a desorption/adsorption cycle produced some mechano-sorptive creep since the sample deflection produced during desorption was not fully recovered during adsorption. The production of compression set emerges as the most suitable explanation for this behavior.