Near-tip microcrack shielding in advanced ceramics

Recent manufacturing of advanced ceramics has developed phase transformation and cracks tilted or bridged to enhance ceramic-inherent toughness. However, main crack and near-tip microcracks interaction is another prominent means in toughening of the ceramic materials. In this study, mechanics of discrete model combined with alternative iterating numerical technique is developed and applied in assessment of main-microcrack interaction. Consequences of main microcrack interaction can either shield or amplify the resulting main crack stress intensity factor, which accounts for the increase or decrease of ceramic toughness. Numerical outcomes show good agreement with the available solutions in the literatures; in addition results also reveal that the toughness shielding or amplification is dependent on the type of loadings as well as location/orientation of the microcrack. Nevertheless, residual normal stress plays an important role in shielding/amplification region trade-off. This work may provide a useful quantitative tool in ceramic design and a valuable insight into main micro interaction phenomenon.