延性材料の切欠引張強さ(第2報)

抄録

Notch tensile tests are carried out to evaluate the effects of stress triaxiality at the net section and uniaxial tensile properties on the notch tensile strength. Notched specimens with U-shaped circumferential notches of three different notch radii and three different notch depths are employed. These specimens are made of four kinds of ductile materials chosen so that the difference in ductility may be wide. The notch strength ratio increases with the stress triaxiality factor proportional to the ratio of hydrostatic to equivalent stress, and with the ratio of local to total elongation in engineering stress-strain curves obtained from uniaxial tension tests. The notch strength ratio is determined by the multiplication effect of these two factors. The value of the notch strength ratio can be predicted by the experimental equation composed of the product of the ratio of local to total elongation and the stress triaxiality factor. Notch strengthening is caused by the above two primary factors.