Description of strengthening mechanism in layered ceramic composites

0448574 - ÚFM 2017 RIV CH eng C - Konferenční příspěvek (zahraniční konf.)
Štegnerová, Kateřina - Náhlík, Luboš - Hutař, Pavel
Description of strengthening mechanism in layered ceramic composites.
Advances in Fracture and Damage Mechanics XIV. Zurich: Trans Tech Publications, 2016 - (Bajić, D.; Tonković, Z.; Aliabadi, F.), s. 93-96. Key Engineering Materials, 665. ISBN 978-3-03835-541-0. ISSN 1013-9826.
[FDM 2015 International Conference on Fracture and Damage /14./. Budva (ME), 21.09.2015-23.09.2015]
Grant CEP: GA ČR(CZ) GA15-09347S
Institucionální podpora: RVO:68081723
Klíčová slova: layered ceramic composites * residual stresses * crack propagation * strain energy density factor
Kód oboru RIV: JL - Únava materiálu a lomová mechanika
www.scientific.net/KEM.665.93

During the last years many researchers put so much effort to design layered structures combining layers of different materials in order to improve low fracture toughness and mechanical reliability of the ceramics. It has been proven, that an effective way is to create layered ceramics with strong bonded interfaces. After the cooling process from the sintering temperature, due to the different coefficients of thermal expansion of individual constituents of the composite, significant internal residual stresses are developed within the layers. These stresses can change the crack behaviour. This results to the higher value of so-called apparent fracture toughness, i.e. higher resistance of the ceramic laminate to the crack propagation. The contribution deals with a description of the specific crack behaviour in the layered alumina-zirconia ceramic composite and its strengthening mechanism. The main aim is to clarify crack behaviour in the compressive layer and provide computational tools for estimation of crack behaviour in the field of strong residual stresses. The crack propagation was investigated on the basis of linear elastic fracture mechanics. Finite element models were developed in order to obtain a stress distribution in the ceramic laminate containing a crack and to simulate crack propagation. The sharp change of the crack propagation direction was estimated using criterion based on the strain energy density factor. This change of the crack propagation direction and next crack propagation parallel to the materials interface is connected with higher energy consumption and represents the main reason for higher apparent fracture toughness of ceramic laminates with strong interfaces. Estimated crack behaviour is qualitatively in a good agreement with experimental observations.
Trvalý link: http://hdl.handle.net/11104/0250243