Mechanosorptive creep of Norway spruce on the tissue scale perpendicular to grain.

Mechanosorptive creep strain (MCS) is a strain component that can dominate the overall deformation behavior of wood components under load and changing moisture. In this work, the MCS behavior of Norway spruce (Picea abies) tissues is investigated in the anatomical directions perpendicular to grain and different loading degrees (LD). The MCS is evaluated through a strain decomposition of the total strain, which is determined using a computer-controlled digital image correlation (DIC) system. It is shown that the common assumption of a scalar relation between mechanosorptive creep compliance (MCC) and the orthotropic, moisture-dependent elastic one is questioned by experiments.