切欠き試験片の弾塑性ひずみ挙動の研究(7) : Neuber則およびひずみ推定法の実験的検討のまとめ

概要

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Some static tests have been conducted in order to investigate the strain concentration factor and the Neuber rule of notched specimens by using strain gages. From the total consideration on experimental results obtained in these tests, some conclusions can be drawn as follows. The strain concentration factor depends on mainly the elastic stress concentration factor, the stress level and the notch radius. ASME Code Case N47 method to estimate the strain at a notch root becomes conservative from the comparison between the experimental results under tensile load, plane bending load and the estimated results in case of the steel, but this method dose not become conservative in case of aluminum alloy. The safety limit of this method is shown in the relationship between the radius of notch root and the critical strains in case of several elastic stress concentration factors. The experimental values multiplied the strain concentration factor by the stress concentration factor in the steel becomes nearly the 2nd power of the elastic stress concentration factor (K_t^2) when the applied stress reaches the yield stress at a notch root, and the experimental values bocomes smaller than K_t^2 with an increase of the applied stress. But, in the aluminum alloy the experimental values become nearly equal to K_t^2 in the applied stress region of 160∿250MPa. In this paper these experimental results and discussions have been presented.