混合モード負荷を受けるき裂からの延性き裂発生挙動

概要

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Behavior of ductile crack initiation from a crack under mixed mode I-II loading has been investigated on a weldable structural steel SM41A. Elastic-plastic fracture toughness tests were carried out on the single-edge-cracked specimens subjected to bending moment and shearing force. The ductile crack initiation from the mixed mode crack occurred in two types - fibrous-type and shear-type - depending on the loading mode. When the mode I component was more predominant,the fibrous-type crack was initiated by the coalescence of microvoids. On the other hand,under the mode II predominant loading,the shear-type crack initiation occurred by large shear deformation. The applicability of J-integral concept to the ductile crack initiation from a mixed mode I-II crack was examined. The condition of ductile crack initiation from a mixed mode crack was shown by contour line on the J_I-J_<II> diagram,J_I and J_<II> being the mode I and Mode II components of J-integral,respectively. The condition of crack initiation for mode II crack,J^i_<II>,was different in value from the condition of crack initiation for mode I crack,J^i_I.
社団法人日本材料学会の論文
1990-08-15