ASSESSMENT OF TIMBER DRYING SCHEDULES BY EVALUATION OF DAMAGE RISKS

The macroscopic description of drying kinetics and the estimation of the corresponding moisture profiles are coupled by a simple diffusion model. This model describes correctly the drying of a board in a kiln, using a constant mass-transfer coefficient associated with the drying stage under consideration. Calculations of both the profiles of moisture gradients and time evolution of these gradients, have been made. These data are inputs for a simple rheological model that is used to define a criterion for the ''limit of damage'' which is based on the risk of the appearance of shakes. With this model it is possible to validate new or currently-used drying schedules, based on moisture content rather than time, by simulating the mechanical response of the wood piece during the drying, and comparing this with the criterion for the limit of damage.