切欠の鈍い試験片における切欠引張強さ比とひずみ硬化指数の関係

摘要

機械・構造物の破断時に加わった引張荷重の上限値rnを，機械的特性値に基づいて簡便に推定するため，前rn報では，切欠試験片の破断に要した最大応力であるrn切欠引張強さの応力三軸度依存性について検討した．rnその結果，切欠引張強さと引張強さの比率で示した切rn欠引張強さ比の上限値は，ひずみ硬化指数と明確な相rn関を示しており，その低下とともに上昇することを明rnらかにした．%In order to develop the relationship between the notch strength ratio, defined as the notch tensile to tensile strength ratio, and the strain hardening exponent, the rate of increase in stress with elongation was investigated on the notched specimens associated with strain hardening ability of the materials. The plastic constraint resulting from strain localization due to low rate of strain hardening raised the stress-elongation curves distinctly. Hence, the stress increase rate increased with decreasing strain hardening exponent for the notched specimens with widely different notch acuity. The useful correlations were thus established to estimate the tensile load required to break the blunt notch specimens as well as the sharp notch specimens from strain hardening exponent.