Modelling the creep behaviour of wood cantilever loaded at free end during drying.

摘要

A new approach to modelling the creep behaviour of a wood cantilever loaded at free end under constant moisture content and under drying conditions is developed. This approach is based on equilibrium equations of cantilever beam theory and allows the computation of stress, strain, and displacement fields through the thickness without any assumption on stress distribution. The analysis is restrained to a modified Burger model that takes into account a moisture content change in wood, although it can be extended to any type of rheological model. In constant hygrothermal conditions, the computed stress field is the same as the one based on equations of elastic cantilever. In drying conditions, a moisture gradient takes place through the thickness, and thus, a nonlinear stress distribution appears and the location of the neutral axis moves away from the geometrical centre of the cross-section. The main advantage of the proposed approach is that it can be used to simulate experimental creep bending tests in the presence of moisture content gradients. Accordingly, bending tests should be appropriate to identify both viscoelastic and mechano-sorptive creep parameters..