Study on notch stress–strain response of blunt side-notched specimen with finite residual width

Abstract

The stress–strain curve at the notch root can be an essential basis for studying the elastic–plastic deformation behavior of notched structure. However, current notch stress–strain studies rarely consider the effect of a finite residual size at the notch root. The blunt side-notched specimens with finite residual width are designed in this work. The material of side-notched specimen is the TC4 titanium alloy. The notch-root strain is measured using the 3D-DIC and an elastic–plastic finite element analysis is performed. It is found that the notch constraints of the finite residual width side-notched specimens are plane stress, which may not be affected by the notch-root radius of curvature. Experiment verification shows that both Neuber’s rule and ESED would underestimate the notch root strain in the plastic stage, and the main reason is that the stress concentration caused by the finite residual width is not considered. To compensate for the deficiency of the traditional method of describing stress concentrations using only K_t, a geometric concentration factor K_g is proposed. K_g can simultaneously reflect the effect of both K_t and the finite residual width on plastic deformation. By introducing the K_g, the accuracy of Neuber’s rule and ESED in describing notch stress–strain has been significantly improved.