Research on aluminum alloy sheet thermoplastic deformation behavior based upon warm bulging test

Gaoshen Cai,Sergei Alexandrov,Lihui Lang,Xiaojun Zhou

doi:10.1063/1.4942817

Gaoshen Cai, Sergei Alexandrov + Show 2 more

Open Access

https://doi.org/10.1063/1.4942817

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Abstract

The rate of fluid pressure variation is a crucial factor to indicate the forming speed and the pressure rate is applied to be one factor that can influence the deformation of material in warm sheet hydroforming. In this study, warm bulging test was conducted to obtain bulging pressure-height curves with different temperatures and pressure rates. Fitting the bulging pressure-equivalent strain curves obtained using bulging test with surface fitting method, the fitted equation of bulging pressure on equivalent strain and pressure rate was achieved, and the fitting result shows a good accordance with experimental and calculated values. Then, the relation between pressure rate and strain rate was obtained. The results of warm bulging test indicated that the deformation behavior of metal material is sensitive to pressure rate, which is of great significance for warm sheet hydroforming.

Highlights

One of the most crucial research topics is to confirm the material properties in metal material deformation behavior.[1]
The results of warm bulging test indicated that the deformation behavior of metal material is sensitive to pressure rate, which is of great significance for warm sheet hydroforming
Uniaxial tension under hot environment is still the most popular method used to implement material property test (Fig. 1(a)), from which exact stress-strain curve is obtained to carry on research on warm sheet hydroforming

Summary

INTRODUCTION

One of the most crucial research topics is to confirm the material properties in metal material deformation behavior.[1]. Uniaxial tension under hot environment is still the most popular method used to implement material property test (Fig. 1(a)), from which exact stress-strain curve is obtained to carry on research on warm sheet hydroforming. In consideration of the particularity of through thickness normal stress induced by liquid pressure during warm sheet hydroforming,[3,4,5] couples of test methods are presented to fit with the stress state characteristics reflected in warm hydroforming The authors suggest that it is of great significance to research the warm/hot sheet hydroforming technology to obtain the material stress - strain curve by warm/hot sheet bulging test.[11,12]

Theory of bulging test to obtain stress-strain curve

Consideration of controlling pressure rate in bulging test

Bulging machine and equipments

Experimental results

Relation between pressure rate and strain rate

CONCLUSIONS