Abstract
In order to characterize the deformation and true stress–strain relation of metal tubes, the geometry of tube walls after necking in uniaxial tension need to be determined. The paper investigated the necking process of metal tube. A large number of tensile tests and finite element analysis of 1Cr18Ni9Ti tubes with different sizes were conducted. It was found that the geometry of outer tube wall in the necking region can be described using a logistic regression model. The final geometry of the tube is determined by original tube diameter and wall thickness. The offset of tube walls are affected by two competing factors: volume constancy and necking. The offset distances of outer and inner walls are mainly affected by original wall thickness. The length of the necking zone is more influenced by original tube diameter. Tube elongation at fracture increases slightly as tube diameter gets larger, while the wall thickness has almost no impact on the elongation.
Highlights
Metal tubes have been widely used in many industrial applications because of their special characteristics including light weight, high strength, energy absorption [1], etc
The tube size is defined by its outer diameter (OD) and inner diameter (ID) or wall thickness (WT)
X = 0 corresponds to the minimum ODf location after study, the origin O of the coordinate is selected at the center point of the straight line which coincides necking y direction pointsXopposite to the tube axis
Summary
Metal tubes have been widely used in many industrial applications because of their special characteristics including light weight, high strength, energy absorption [1], etc. Bridgman’s method is one of the widely accepted approaches, which generates analytical stress–strain relations by considering the geometry of the neck, such as curvature of the profile and diameter [27]. This method was further developed by other researches and has been applied to tensile specimens with both circular cross sections and rectangular cross sections [28,29,30]. An analytical formula was proposed to depict the curvature profile, which could be used in combination with Bridgman’s equation in the future to derive the post-necking stress–strain relationships of tubes. The neck diameter at fracture and elongation of different tube dimensions in uniaxial tension was discussed, which is a good industrial reference for design analysis
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
