Stress distribution evaluation at localized necking area using the virtual fields method with digital image correlation

Abstract

In this paper, based on the virtual fields method (VFM) and displacement measurement using digital image correlation, we propose a method for evaluating the equivalent stress and the equivalent plastic strain relationship and the stress distribution even after the onset of the local necking. The proposed method identifies a piecewise relationship between the equivalent plastic strain and the equivalent stress, resulting in model-independent relationship. The effectiveness of the proposed method is demonstrated by applying it to the simulation data obtained using a finite element method. Results show that the proposed method can identify the piecewise relationship between the equivalent plastic strain and the equivalent stress. In addition, the proposed method is applied to the experimental displacement distributions around notches of a thin high-strength steel plate specimen. Experimental results show that the reasonable post-necking stress-strain relationship together with the stress distributions are obtained using the proposed method.