Regensburg 2013 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 62: Topical Session: Fundamentals of Fracture - Stochastic Aspects

MM 62.3: Vortrag

Donnerstag, 14. März 2013, 18:00–18:15, H4

Failure Prediction in Silicon Nitride based on a Probabilistic Micromechanical Approach — •Yamen Othmani and Thomas Böhlke — Chair for Continuum Mechanics, Institute of Engineering Mechanics, Karlsruhe Institute of Technology (KIT), Kaiserstrasse 10, 76131 Karlsruhe, Germany

Silicon nitride ceramics are prime structural materials for several challenging assignments and applications. This is due to their outstanding high stiffness, high-temperature strength and, especially, their high fracture toughness. However the structural use of these materials is restrained because of the occurrence of damage phenomenon under severe working conditions. Many approaches, including fracture mechanics, could be adopted to predict the failure of silicon nitride. Nevertheless, the strengths of such materials are statistical in nature and the damage progression is stochastic. Therefore, the application of statistical methods to evaluate the failure of ceramics is a versatile approach. In the present work, multivariate weakest link approach is developed and used in conjunction with a stochastic analysis of the local elastic fields to determine the failure probability of sintered silicon nitride. The originality of the work is reflected by the employment of second-order estimates in the analysis of elastic field fluctuations. The following assumptions have been taken into consideration: The constitutive phases of silicon nitride are considered to be isotropic and linear elastic. The strain field is compatible which implies a vanishing distribution of eigenstresses.