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O.Ševeček et alii, Frattura ed Integrità Strutturale, 34 (2015) 362-370; DOI: 10.3221/IGF-ESIS.34.40 368 O UTLOOK he model can be applied to study the combined effect of residual stress and thickness of the compressive embedded layers, which can define lower and upper bounds for the absence or presence of edge cracks in ceramic laminates. Based upon this model, recommendations on layer architectural design can be given, which should prevent the formation of edge cracking in laminate systems designed with internal residual stresses. An extension of this model will be the study of edge crack formation and extension considering the combination of residual stresses and layer thickness as design parameters. In such case, several possibilities for improvement in the mechanical properties of the system (i.e. fracture resistance and strength) are to be expected. C ONCLUSIONS his work presents a novel approach to predict the onset and propagation of surface cracks (namely edge cracks) in ceramic laminates, associated with the residual stresses developed after cooling down from the sintering step. A full parametric 2D finite element model was developed to simulate the initiation and propagation of the edge crack in the compressive layers. The conditions for crack initiation/propagation were assessed using a coupled stress- energy criterion. The analysis only requires the values of the elastic moduli and Poisson’s ratio of the layers, the coefficient of thermal expansion, the toughness and the tensile strength of the compressive layer. There is no adjustable parameter and there is no need to assume the presence of surface defects to initiate fracture. It was further found that, for a given thickness of the compressive layer, no edge crack is to initiate for relatively low internal (in-plane) compressive residual stress in the layer. For higher stress values, edge crack may initiate and grow in a stable manner. Finally, for relatively higher stress values, the formation of edge cracks will be followed by the fracture of the entire layer in an unstable fashion. In future work, we will focus on the validation of the obtained results on different real specimens with various thicknesses and levels of residual stresses, aiming to provide guidelines for the fabrication of layered ceramics with controlled surface cracks. A CKNOWLEDGEMENTS he work has been supported by the NETME Centre established thanks to a financial support of the European Regional Development Fund under the Operational Program Research and Development for Innovation. The presented results have been obtained within NETME CENTRE PLUS (LO1202) project co-funded by the Czech Ministry of Education, Youth and Sports within the support program National Sustainability Program I. A financial support of the Czech Science foundation under the project no. 14-11234S is also gratefully acknowledged. R EFERENCES [1] Griffith, A.A., The phenomenon of rupture and flow in solids, Phil. Tran. Roy. Soc. London, A221 (1920) 163-198. [2] Kingery, W.D., Bowen, H.K., Uhlmann, D.R., Introduction to ceramics. New York: John Wiley & Sons., (1976) 1032. [3] Danzer, R., A general strength distribution function for brittle materials, Journal of the European Ceramic Society, 10 (1992) 461-472. [4] Morrell, R., Fractography of Brittle Materials. Teddigton: National Physical Laboratory, (1999) 86. [5] Danzer, R., Mechanical Failure of Advanced Ceramics: The Value of Fractography, Key Engineering Materials, 223 (2002) 1-18. [6] Lawn, B., Fracture of Brittle Solids. 2nd ed. Solid State Science, New York, USA: Cambridge University Press. (1993) [7] Munz, D., Fett, T., Ceramics. Mechanical Properties, Failure Behaviour, Materials Selection. Materials Science, ed. R. Hull, et al., Berlin: Springer (1999). [8] Danzer, R., Lube, T., Supancic, P., Damani, R., Fracture of advanced ceramics, Advanced Engineering Materials, 10(4) (2008) 275-298. T T T