A THERMO-HYDRO-MECHANICAL APPROACH FOR CRACKING AND ANISOTROPIC SHRINKAGE IN CELLULOSE-BASED POROUS MATERIALS

Moisture removal in cellulose-based porous materials induces complex deformation phenomena driven by coupled heat transfer, moisture transport, and mechanical response. In this study, a fully coupled thermo-hydro-mechanical (THM) model is developed to investigate anisotropic shrinkage, stress evolution, and crack initiation during drying. The proposed framework integrates moisture-dependent transport properties, orthotropic elasticity, and a stress-based damage criterion within a unified finite element formulation. The results show that moisture gradients are the dominant factor governing internal stress development, leading to significant tensile stress localization near exposed surfaces. The model successfully predicts anisotropic shrinkage behavior, with tangential (~9.2%) and radial (~4.3%) strains markedly exceeding longitudinal deformation (~0.2%). Damage analysis reveals that crack initiation occurs at intermediate drying stages and propagates inward following the moisture gradient. A parametric study demonstrates that moisture diffusivity and sample thickness are the most influential parameters controlling stress magnitude and failure risk, whereas thermal effects play a secondary role. Validation against literature data confirms the capability of the model to reproduce realistic drying-induced behavior in cellulose-based materials. The findings provide new insights into the coupled mechanisms governing deformation and damage, highlighting that failure is primarily transport-controlled. The proposed THM framework serves as a predictive and optimization tool for minimizing defects and improving the structural integrity of cellulose-based materials in industrial applications.