Effect of Temperature on the Strain Recovery in Wood

Abstract

UNTIL recently, strains occurring beyond the limits of plastic creep in wood were, because of the similarity to creep in crystalline solids, identified with micellar creep in cellulose and considered as plastic strains¹. Investigations carried out by Ivanov², in which swollen wood was subjected to cyclic loading and unloading with compression stresses above the limit of plastic creep along the fibre direction, showed that after each cycle of loading and unloading, both elastic and residual strains are increasing. Moreover, Ivanov found that strains occurring during compression beyond the limits of plastic creep, when wood is compressed along the direction of fibre length until the moment of showing symptoms of failure, were not connected with microscopic displacement of wood structure components. On the other hand, strains occurring beyond the limits of plastic creep when wood is compressed across the fibre direction are, to some extent, related to the deformations of cell cross-section shapes³.