2007 Volume 56 Issue 3 Pages 244-251
Numerical simulation method for analyzing fracture behavior of porous ceramics is developed on a basis of initiation of micro-cracks. The deformation and fracture behavior are numerically simulated under four-point bending. A mixed mean stress model is adopted as a condition of the initiation and propagation of micro-cracks. Analytical models are made of an aggregation of circular grains whose are average size is 150μm. The micro-cracks are located in a bond of each grain. In a stress-strain relationship, as a notch depth and porosity increase, the stress-strain curve becomes nonlinear. The micro-cracks initiate near large pores and a main crack propagates intricately. When the notch depth is small, the fracture occurs not from the notch root. Size of a non-damaging defect can be evaluated by the proposed method. R-curve calculated is independent of the notch depth. These results calculated agree very well with experimental results.
