Crack path prediction in layered ceramics designed with residual stresses O. Ševeček 1 , R. Bermejo 2 and M. Kotoul 3 1 Materials Center Leoben Forschung GmbH, Roseggerstraße 12, 8700 Leoben, Austria, Email: sevecek@seznam.cz 2 Montanuniversität Leoben , Institut für Struktur- und Funtionskeramik, Peter-Tunner Straße 5, 8700 Leoben, Austria. Email: raul.bermejo@unileoben.ac.at 3 Brno University of Technology, Institute of Solid Mechanics, Mechatronics and Biomechanics, Faculty of Mechanical Engineering, Technická 2, 616 69 Brno, Czech Republic, Email: kotoul@fme.vutbr.cz ABSTRACT. In this work a computational tool, aiming to predict the crack propagation (i.e. straight propagation, single deflection or bifurcation) in layered ceramics designed with internal residual stresses, is developed. They consist of two material layers with different properties, alternated in a multilayer structure. The internal stresses developed during sintering are associated with the thermal expansion mismatch between adjacent layers and volume ratio between both materials. The computational model is based on Finite Fracture Mechanics theory, especially focused on cracks terminating at the interface between two different material layers. The method utilizes a matched asymptotic procedure to derive the change of potential energy associated with the fracture process. The crack follows the path which maximizes the energy released in the fracture process. A combined loading (thermal and mechanical) is taken into consideration to clarify the influence of the residual stresses on the crack path during fracture. The results predicted by the proposed fracture criterion are in good agreement with the experimental observations on the real laminate. INTRODUCTION Layered ceramics have become an alternative choice for the design of structural ceramics with improved fracture toughness and mechanical reliability. The brittle fracture of monolithic ceramics has been overcome by introducing layered architectures of different kind, i.e. geometry, composition of layers, residual stresses, weak interfaces, etc. The main goal of such layered ceramics has been to enhance the fracture energy of the system. Among the various laminate designs reported in literature, two main approaches regarding the fracture energy of the interfaces must be highlighted. On the one hand, laminates designed with weak interfaces have been reported to yield significant enhanced failure resistance through interface delamination [1-8]. The fracture of the first layer is followed by crack propagation along the interface, the so- 87