Models for predicting drying stresses and strains in a film cast on a substrate: An alternative approach

Models based on Biot's theory for the deformation of a saturated porous body are presented for the stress and strain produced during drying of film cast on a substrate. A two-stage drying process is considered, where a constant-rate period is followed by a falling-rate period. The compressive stress that develops in the body is proportional to the evaporation rate and increases as the permeability of the body decreases. The maximum stress occurs at the drying surface at the end of the constant-rate period. During the falling-rate period, the receding drying front divides the material into saturated and unsaturated regions; the saturated region is subjected to compressive stress while the stress in the unsaturated region would be released if the solid network is elastic as assumed in the analysis. The receding drying front is accounted for in the models.