セラミックスの異物衝突損傷における静的初期応力の影響

抄録

Ball impact tests were carried out to evaluate the effect of static initial stress field on the foreign object damage of ceramics. Two kinds of balls, steel and Si₃N₄, the size of which was 3mm in diameter were used as the projectiles, and five kinds of SiC and Si₃N₄ ceramics were used as the target specimens of 7.5×10×85mm size. After the impact tests, three point bending tests were carried out to evaluate the residual strength of the specimens, and the difference in failure with ball contact was discussed taking the results of numerical analyses into consideration.
The results obtained are summarized as follows;
(1) From the impact tests, the critical condition to produce the effect of initial stress on foreign object damage became clear.
(2) From the numerical impact fracture analyses, it was found that the effect of residual tensile stress was caused by an increase in compressive permanent deformation in the target at impact due to the initially applied static load.
(3) The mechanical property of the target material subjected to compressive load is an important parameter to evaluate the foreign object damage of Si₃N₄ ceramics.