Investigation of circular aluminium tube expansion by rigid die as energy absorbers using digital image correlation technology

Abstract

This paper investigates the expansion of circular aluminium tubes using a rigid die under quasi-static loading conditions through experiments and finite element simulations. This study primarily focuses on the expansion of thin-walled tubes with a thickness ranging from 3.95 to 5 mm, and the finite element model is in good agreement with the experimental results. Additionally, the study emphasizes the impact of the coefficient of friction, energy dissipation properties and the diameter-to-thickness ratio on the energy expenditure associated with the expansion process of aluminium tubes using a rigid die. This study use Digital Image Correlation (DIC) technology to evaluate pictures obtained during experimental procedures, enabling accurate quantification of displacements, stresses, and rotations of major planes. The findings indicate that the energy absorption resulting from friction plays a significant role, with the coefficient of friction serving as a important parameter throughout the expansion process. The energy absorbed by the friction between tube-die contact surfaces was significantly higher than that absorbed by the plastic bending of the aluminium tube. For specimen AT-5.0-1, the energy absorbed by friction and bending is 3352 and 570 J, respectively. Result shows that a notable increase in the ultimate load, rising from 46.03 to 61.54 kN, is required for expanding the aluminium tube with a thickness of 3.95 to 5.0 mm. The local strain patterns seen on the surface of the tube offer useful insights, therefore enhancing researchers’ ability to examine particular points on the specimen’s surface without the need for fixed reference points prior to conducting experiments.