Determining the Yield Surface of a Metal Using Notched Strip Specimens: Geometry Optimization

Abstract

AbstractDetermining the full yield surface of a metal by experimental means is a rather complex task, due to the need to subject the material to a multi‐axial stress state that includes shear. However, an interesting concept (originally credited to Hill and Bijlaard) has been proposed, whereby metal strips with oblique notches are loaded in uniaxial tension. This specific shape forces a narrow yield neck to develop between the roots of the notches, subject to multiaxial straining. The presented research aimed to further develop and optimize this concept. It was previously suspected that the geometry of the test specimens has a potentially significant effect on the results of the experiment. By means of the finite element method, a parametric study was completed to evaluate which geometric variables have the largest influence on the results and to determine the range within which these parameters yield reliable results. It was discovered that certain variables, such as the width of the neck and the radius of the notch root, had a significant impact on the results, whereas others, such as the neck angle or the opening angle of the notch, had very little or even no influence at all. Based on these results, a specific geometry was proposed for the test specimens, as a first step towards a standardized test procedure.