Stress Development in Drying Fibers and Spheres

Stress development during drying is a critical factor that affects the final structure and properties of a coated fiber or spherical product. Stress development during drying of the coating is due to nonuniform shrinkage and physical constraints. In this study, a large deformation elasto-viscoplastic model is developed to predict stress development in drying fibers and spheres after the coatings solidify. From the model, stress evolution in the drying fibers/spheres can be predicted by a partial differential equation of diffusion in one dimension, a first-order partial differential equation of pressure distribution, and two ordinary differential equations on local evolution of the stress-free state. The system of equations is solved by the Galerkin/finite element method in the one dimensional axial/ spherical symmetric coatings. Solutions show changes in solvent concentration and viscous stress as the coating dries.