Notch Tensile Strength of Ductile Materials

Abstract

Notch tensile tests are performed to evaluate the effect of stress triaxiality at the net section, and the uniaxial tensile properties on the notch tensile strength. Notched specimens with a U-shaped circumferential notch of three different notch radii and a constant notch depth are employed. These specimens are made of eight kinds of ductile materials selected 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 of the nominal stress-strain curve obtained from the uniaxial tension test. The notch strength ratio is independent of the magnitude of the reduction in area or the total elongation. It is clarified that 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. © 1986, The Japan Society of Mechanical Engineers. All rights reserved.