Damage analysis of microwave-dried materials

Abstract

The aim of this article is to analyze the drying-induced stresses and destruction of ceramic-like materials during their microwave drying. The kinetics of microwave drying at various microwave power levels are determined experimentally and numerically, and the distributions of temperature and moisture content in the tested samples are visualized with infrared camera and presented graphically. The experiments are performed on kaolin-clay samples, where destruction provoked by microwave drying is visualized on photographs taken with the photo camera and microscope. The thermo-hydro-mechanical model of drying elaborated by authors is used to determine the distribution of stress components and to calculate the effective stress required to induce the failure of material. The effective stress is formulated with the use of the energetic criterion, and the material spots prone to damage are predicted numerically. The numerically predicted spots are compared with the experimentally appointed places of material damage and a good adherence of the numerical predictions with experiments is confirmed. © 2011 American Institute of Chemical Engineers AIChE J, 2012