一方向性珪素薄鋼板の疲労き裂進展挙動についての二三の実験結果 : 負荷, 予き裂の方向を変えた大気中の場合(<特集>疲労)

概要

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In order to investigate Mode II and III besides Mode I fatigue crack propagation in grain oriented silicon iron thin plates with coarse grains, some experiments were carried out, selecting favorable directions of loading and starting notches for these modes. Mode II crack growth was expected by loading parallel to rolling direction of specimens with starting notches along a preferential slip direction, however, Mode II crack growth along this direction could not continue beyond about one mm in any case and the crack suddenly bent 110° to conjugate preferential slip direction. Striation-like patterns with a few μm spacing, which corresponded to crack growth during hundreds cycles, were observed in these fractographs. These results suggest existence of some substructures caused by cycling slips on one direction during hundreds cycles which may arrest continuous crack growth on one plane. The tensile test loaded perpendicular to folling direction showed enough out of plane shear deformation and fracture ductility. Mode III crack growth was expected by loading perpendicular to rolling direction of specimens, but Mode I crack growth with brittle striation occurred and any shear lips could not be observed.
社団法人日本材料学会の論文
1999-10-15