459 窒化ケイ素セラミックスのき裂開閉口挙動に及ぼす圧縮負荷の影響(GS-13 き裂(4))  [in Japanese] 459 Beneficial Effect of Compressive Loading on Crack Opening Behavior in Silicon Nitride Ceramics  [in Japanese]

The effect of stress shielding near the crack tip in Silicon Nitride ceramics was investigated using the Laser speckle strain / displacement gage by which a small crack opening displacement(COD) can be measured. A special attention was put on the influence of compressive loading on the stress shielding effect. From the result of COD measurement, it was found that the COD in ceramics was strongly affected by the applied stress ratio. Especially, the compressive loading was found to play an important role on the development of the stress shielding effect.