円孔の近傍に亀裂を有する材の脆性破壊挙動に及ぼす干渉の影響

抄録

Fracture behaviors in the plate with crack in the vicinity of hole such as opening hole and fastener hole in the structure are different from those in the plate with only a crack, due to interaction between crack and hole. To obtain basic data for safety assessment on plate like that, it is necessary to clarify the effect of interaction on brittle fracture behaviors such as fracture strength and critical COD.
Experimental investigation has been carried out on fracture behaviors in the plates with various F_Ia values under uniform tension, where, F_Ia=K_Ia/σ√πc, K_Ia, σ and c are stress intensity factor at the crack tip in the vicinity of circular hole, remote tensile stress and semi-crack length respectively.
Main results obtained are as follows :
(1) The brittle fracture stresses of the plates with large F_Ia values (F_Ia>1.3), that is, in the case of high interaction of crack and hole, are not so much lower than those of the plate with only a crack, while those of the plates with small F_Ia values (F_Ia≤1.3) are roughly equal to those of the plate with only a crack.
(2) The critical COD values in the plates with large F_Ia values are larger than those in the plates with small F_Ia, values or crack only, while those in small F_Ia, values are roughly equal to those in crack only.
(3) The bi-axialities of stresses in crack tip zone in large F_Ia, values are smaller than those in small F_Ia values or crack only, while there is no significant difference between those in small F_Ia values and those in crack only.
(4) The phenomena described in (2) can be explained by the phenomena described in (3).