Loading configuration effects on the strength reliability of alumina-zirconia multilayered ceramics

The loading configuration effects on the strength reliability of alumina/zirconia multilayered systems, designed with internal compressive stresses, have been investigated. The existence of a threshold strength behaviour, as previously assessed under longitudinal flexure, has been evaluated by indentation-strength tests under transverse flexure. Additionally, the influence of flaw interactions on the strength reliability under both loading configurations has also been studied. Experimental findings show a higher strength level under transverse flexure, as far as the failure-controlling flaw is located between two compressive layers. It is found however that multiple artificial and natural flaws may interact affecting the strength of the specimen under transverse loading. As a consequence, although higher strength values result from this configuration, a more reliable design is rather attained when the loading axis is applied normal to the layer plane, a loading mode where similar effects are negligible.