FE-modelling of the toughening mechanism in whisker reinforced ceramic-matrix-composites

Abstract

Ceramic-matrix-composites (CMCs) are fast replacing other materials in many applications where the higher production costs can be offset by significant improvement in performance. However, due to their lack of toughness they are prone to catastrophic failures. Hence, the important consideration in the design of CMCs is to achieve satisfactory toughening. Recent experimental studies of whisker-reinforced ceramics have shown that substantial improvements in fracture toughness can be achieved via the mechanisms of whisker bridging, whisker pull-out and crack deflection. This paper demonstrates the use of finite element method to model the whisker/matrix interface through isoparametric interface elements. A micro mechanical finite element model which uses isoparametricformulation has been presented. The micro mechanical finite element model is then validated by characterising the non-linear force-displacement response of α-SiC ceramic whisker embedded in Al 2O 3 ceramic matrix and comparing it with the simplified analytical solutions. The FE model is then used to demonstrate the effect of whisker/matrix interface shear strength on the toughening behaviour, and failure modes of SiC whisker reinforced Al 2O 3(matrix)/SiC (whisker) ceramic composite.