NUMERICAL MODELING OF RESIDUAL THERMAL STRESS IN Si$_{3}$N$_{4}$ BASED HIGH-POROUS COMPOSITE CERAMICS

Abstract

Abstract:Modeling of residual thermal stresses arising in silicon nitride-based porous fibrous ceramic materials with reinforcing dispersed inclusions was carried out. Calculations were made within quasi-static linear thermoelasticity on the presumption that the initial state at which there are no internal stresses in the media is realized during synthesis of the material at temperature of 1450 • C. Modeling was carried out on three-dimensional representative fragments of fibrous structures generated using random algorithms with preset parameters of the materials' microstructure. Influence of the volume fraction and the size of the fillers in the form of spherical inclusions of silicon carbide on the residual thermal stresses realized within the structure of fibrous porous material is analyzed. It is demonstrated that the level of arising residual stresses can be comparable and, indeed, may exceed the fracture strength of considered porous materials.