粒径の異なるアルミナセラミックスの熱衝撃破壊挙動

抄録

Crack growth behaviors in pre-cracked elliptical specimens subjected to thermal shock were characterized using Disc-on-Rod tests developed by the authors. The central area of heated specimen was quenched by means of contacting with a cool copper rod. Crack growth with various Mode I/Mode II ratio was obtained by changing the crack angle. The crack path was recorded during tests and introduced into the finite element model. Measured temperature distribution was inserted into the model and thermal stress field was calculated. Fracture mechanical parameters during thermal shock crack growth were then determined using a virtual crack closure method. It was demonstrated that the macroscopically stable crack growth consists of intermittent crack growth with small scale unstable crack and crack arrest. It was also found that crack growth resistance were increased with the crack length. It is worth noting that the larger the grain size was the higher the crack growth resistance was. Consequently, the experimental technique to characterize the fracture mechanical behavior of thermal shock crack was developed in the present study.