アルミニウム鋳造合金における疲労特性のメゾスケール特性からの評価 : 第3報,応力比-1下での複数種の異材粒子を含む金属の切欠き材における疲労限度信頼性の予測

概要

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In this paper, a quantitative prediction method for the gatigue limit reliability of a notched metal with different sorts of inhomogenities is proposed. The fatigue limit of the notched specimen cosists of the microcrack nonpropagation limit σ_<w1>, small crack nonpropagation limit σ_<wd> and macrocrack nonpropagation limit σ_<w2>. The reliabilities of σ_<w1> and σ_<wd> are predicted by the stress-strength model which consists of "statistical characteristics of hardness in a small region" and "statistical characteristics of a mechanical condition in the small region containing the defect under a cyclic stress". The σ_<w2> is predicted by the Linear Fracture Mechanics. The present method was applied to the aluminum cast alloy JIS AC4B-T6 where eutectic Si, Fe compuound and porosity are contained. The fatigue strength at 10^7 tress cycles was defined as the fatigue limit. Then rotating bending fatigue tests of notched specimens with constant notch depth t=0.5mm and various notch root radii ρ=2, 1, 0.3, 0.1mm were carried out. The validity of the present method was examined by comparing predicted results with experimental results.
2006-08-25