Finite Element Analysis of Fracture Strength of Ceramics Considering Both Surface and Internal Defects

Abstract

Structural ceramics are being considered for use in a variety of fields due to their excellent properties. However, ceramics are very sensitive to defects and minute surface defects can affect fracture strength. In addition, the relationship between surface defects and fracture strength exhibits non-linearity, and thus, the conventional linear elastic fracture mechanics may not predict fracture strength. Therefore, there is a need for an accurate method to determine the effect of surface defects on the fracture strength of ceramics. In this study, we developed a method that extends the model proposed by the authors to incorporate fracture strength reduction due to surface defects. This method can reproduce the non-linearity of the relationship between surface defects and fracture strength of ceramics. Then, we discuss about the competing relationship between internal and surface defects. It can also estimate the allowable size of surface defects by combing with the Weibull distribution of fracture strength.