モードI微小表面き裂の進展に及ぼす二軸応力の影響
1993 年 59 巻 562 号 p. 1437-1442
詳細
1993 年 59 巻 562 号 p. 1437-1442
The crack propagation rate da/dN at the specimen surface or db/dN toward the inner direction perpendicular to the specimen surface and crack opening displacement COD of a mode I small surface crack in a round bar are examined under biaxial stresses by means of the combination of plane bending and cyclic torsion. When the stress intensity factor range ΔK* at the deepest point of the crack periphery is the same, db/dN increases with the decrease in biaxial stress ratio C. An analogous tendency is recognized in the relationship between da/dN and ΔK at the specimen surface. A unique relationship is obtained between da/dN and crack tip opening displacement CTOD in spite of C. Thus, it can be concluded that the main factor which controls da/dN is CTOD.
