Failure analysis of textile-reinforced ceramic matrix composites
Werner Hufenbach*, Albert Langkamp*,Lothar Kroll*, Wojciech Błażejewski** *Institut für Leichtbau und Kunststofftechnik (ILK), Technische Universität Dresden 01062 Dresden, Germany **Institut für Leichtbau und Kunststofftechnik (ILK), Technische Universität Dresden 01062 Dresden, Germany
Annals 3 No. 7, 2003 pages 250-254
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abstract The high lightweight potential of modern long-fibre reinforced ceramics for the application in components under complex thermo-mechanical loads can only be used optimally, if the anisotropic fibre reinforcement is designed according to the acting loads. For the component optimisation adapted analytical and numerical simulation techniques as well as suitable realistic failure criteria are required. By applying analytical and numerical computing methods developed so far for fibre- and textile-reinforced ceramics, the thermo-mechanical induced stresses and strains can be sufficiently determined. In contrast, undertaking the failure analysis adapted to textile ceramic structures still remains a source of considerable difficulty. One principal reason for this is that the use of the „homogenisation technique” in the sense of a „blurred” continuum is not permissible for a realistic description of the fracture behaviour of textile-reinforced ceramics. The often applied generalising fracture criteria, such as, for example, the quadratic failure criteria of Sacharov and Tsai-Wu cannot be used to simulate the actual fracture behaviour realistically and there remains a great uncertainties in the interpretation of the results of fracture tests. Only the development of a new type of so-called fracture mode criteria can enable a physically based description of the prevailing failure modes of fibre- and textil-reinforced ceramics. Subsequently, the action plane criterion of Hashin-Puck and the invariant criterion of Cuntze are applied to the failure analysis of fibre- and textile-reinforced SiC ceramics and correspondingly modified. The objective of this paper is to improve the strength analysis of fibre- and textile-reinforced ceramic structures applying novel fracture mode related failure criteria. By means of multi-axial failure tests carried out on reinforced ceramics, the failure mode criteria were able to be verified in the (σ 2, τ21)- and (σ 1, σ 2)-stress planes. Key words: ceramic composites, failure behaviour, simulation, verification