A new method for localized necking detection in uniaxial tensile testing based on a multi-camera DIC system

Abstract

Understanding and predicting the onset and behavior of localized necking is important for the design and optimization of structures and components. Capturing the onset of localized necking more accurately has been a challenge in experimental mechanics. In this paper, a new alternative method for detecting the onset of localized necking in uniaxial tensile tests is presented. This method is inspired by the fact that different behaviors are exhibited as localized necking starts at the different regions of the cross-sectional area. When localized necking begins to occur, the cross-sectional area in the center of the necking area decreases sharply, while the cross-sectional area at the boundary of the necking area no longer decreases. A multi-camera digital image correlation system consisting of four cameras, two placed at the front and two at the back of the specimen, has been developed to measure the cross-sectional area at different positions of the sample. The effectiveness and accuracy of the proposed method are verified through a series of tensile tests and are compared with different localized necking detection methods.