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Structural Engineering and Mechanics
  Volume 60, Number 1, October10 2016 , pages 91-110
DOI: https://doi.org/10.12989/sem.2016.60.1.091
 


Deformation behaviours of SS304 tubes in pulsating hydroforming processes
Lianfa Yang, Ninghua Wang and Yulin He

 
Abstract
    Tube hydroforming (THF) under pulsating hydraulic pressures is a novel technique that applies pulsating hydraulic pressures that are periodically increased to deform tubular materials. The deformation behaviours of tubes in pulsating THF may differ compared to those in conventional non-pulsating THF due to the pulsating hydraulic pressures. The equivalent stress-strain relationship of metal materials is an ideal way to describe the deformation behaviours of the materials in plastic deformation. In this paper, the equivalent stress-strain relationships of SS304 tubes in pulsating hydroforming are determined based on experiments and simulation of free hydraulic bulging (FHB), and compared with those of SS304 tubes in non-pulsating THF and uniaxial tensile tests (UTT). The effect of the pulsation parameters, including amplitude and frequency, on the equivalent stress-strain relationships is investigated to reveal the plastic deformation behaviours of tubes in pulsating hydroforming. The results show that the deformation behaviours of tubes in pulsating hydroforming can be well described by the equivalent stress-stain relationship obtained by the proposed method. The amplitude and frequency of pulsating hydraulic pressure have distinct effects on the equivalent stress-strain relationships-the equivalent stress becomes augmented and the formability is enhanced with the increase of the pulsation amplitude and frequency.
 
Key Words
    tube hydroforming; pulsating; stress-strain relationship; free hydraulic bulging
 
Address
Lianfa Yang, Ninghua Wang and Yulin He: Faculty of Mechanical & Electrical Engineering, Guilin University of Electronic Technology, Guilin 541004, Guangxi, P.R. China
 

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