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1980
Conference Paper
Titel
Slow crack growth and failure prediction for alumina in simulated physiological media
Alternative
Langsames Rißwachstum und Versagensvorhersage für Aluminiumoxid unter Simulation physiologischer Bedingungen
Abstract
The time-dependence of the strength of components made from brittle materials, such as Al2O3 ceramics, can be ascribed to the subcritical slow propagation of preexisting microcracks in the material. Following the fracture mechanics approach, the subcritical crack growth is described by the dependence of crack velocity on the stress intensity factor K1. A double torsion configuration is used for the measurements in air and in simulated physiological liquids. Significant differences are found in the crack velocity vs. load for the materials and environments investigated, with the liquids producing a crack velocity enhancing effect. Using the measured v-K1 dependence and simplifying the load conditions and the geometry of the preexisting cracks the time to failure of a hip endoprosthesis is calculated. From this calculation the maximum allowable flaw depth to achieve a given lifetime can be estimated.
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