Fracture, ceramics, intergranular

R.W., Rice, Ceramic fracture mode Intergranular vs. Transgranular Fracture. Ceramic Transec tions, 64 Fractography of glasses and Ceramics III (JR Varner, VD Frechette, and GD Quinn, eds). Am. Cer. Soc., Westerville, OH, 1996, p.l 53. 

Superplastic ceramics deform without necking and fail by intergranular cracks that propagate perpendicular to the applied tensile axis. Grain size has been considered as a critical factor in superplasticity. In Fig. 8.88, fracture strain is indicated as a function of flow stress in FG ceramics, while the strain-rate sensitivity, m, remains high. In Fig. 8.88, various ceramics are plotted, (the reader is referred to the original works) ... 

To simulate the spontaneous dynamic motion of cracks, we use a 2-D plane strain cohesive/volumetric finite element (CVFE) scheme that has shown great success in the simulation of various dynamic fracture events in brittle media (Xu and Needleman, 1994, Camacho and Ortiz, 1996, Geubelle and Baylor, 1998). As its name indicates, the numerical method is based on the combination of conventional (volumetric) elements used to model the mechanical response of the ceramic material and interface (cohesive) elements introduced to simulate the intergranular failure process. Figure 1 schematically illustrates the CVFE concept. The volumetric elements... 

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