斜め予き裂からの屈折疲労き裂伝ぱ挙動に及ぼす予き裂周辺圧縮残留応力の影響 : 屈折直後の短いき裂の不連続変位分布測定に基づいて

概要

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A testing for bent fatigue crack propagation under mixed-mode conditions was carried out using fatigue and annealed slant precracks with different slant angles, β, defined as the angle between loading and precrack directions in a rectangular plate. As a result, bent fatigue crack from the fatigue precrack with β=45 deg. propagated under mixed-mode conditions with mode II stress intensity factor (K_<II>)_<est> evaluated from the discontinuous displacement measured along the crack. On the other hand, bent fatigue crack from the fatigue precrack with β=60 deg. and from the annealed precracks with both slant angles of β=60 deg. and β=45 deg. propagated under the mode I behavior. This was because the compressive residual stress near the fatigue precrack caused contact to each other between the upper and the lower surfaces of the precrack with the smaller slant angle β. The estimated fracture angles, θ_<est>, calculated using (K_I)_<est> and (K_<II>)_<est> corresponded to the measured fracture angles, θ_<mes>, even for the bent fatigue crack propagation under the mixed-mode condition containing the mode II component. Furthermore, the fatigue crack propagation rates indicated almost the same relationship for all the data, using the mixed-mode effective stress intensity factor (K_M)_<est>, calculated from the discontinuous displacement measured along the bent fatigue crack.
一般社団法人日本機械学会の論文
2006-05-25