Evaluation of fracture strength for ceramics with defects by numerical simulation (2nd report, characteristics of R-curve)

The influence of pre-crack length on an R-curve for ceramics with bridging is investigated by numerical simulation. Generally a pre-crack is introduced into the specimen for measurement of the R-curve. However, it is considered that the R-curve is influenced by the pre-crack length because the bridging stress distribution depends on the pre-crack length. In this study, R-curves are obtained by numerical simulation. In the numerical simulation, we establish an algorithm to evaluate the R-curve based on bridging stress. This algorithm can be used to estimate the characteristics of bridging through a certain R-curve obtained experimentally. Based on the results, it is shown that the R-curve for ceramics with bridging depends on the pre-crack length and the specimen geometry.