3D model simulating the hydro-mechanical state of unsaturated and deformable material during hot air drying

Abstract

A three dimensional model to predict the hydro-mechanical state of unsaturated and deformable material during hot air drying has been proposed. The material viscoelastic behaviour was formulated using Bishop’s effective stress theory for partially saturated material using the liquid saturation as the Bishop parameter. The hydro-thermal and mechanical equations were coupled by the fluid pressure and the solid matter velocity. The model was applied to a deformable material (innovative clay-cellulose fibers composite) subjected to convective drying. A generalized Maxwell model with five elements, whose parameters were measured experimentally and correlated to water content was used to describe the material’s viscoelastic behavior. The hydro-thermal part of the proposed model was validated on the basis of a comparison of experimental and simulated drying rate curves. The Von Mises stress was simulated and compared to the experimental tensile strength in order to predict the time and the region of material failure. For a drying process at95°C, the region of failure risk was identified. The failure may occur on the lateral surface of the slab in contact with air at a drying time of 2.5h.