VALIDATION OF A NEW METHODOLOGY FOR DETERMINATION OF STRESS-STRAIN CURVES THROUGH BULGE TEST
This paper is focused on determining the stress-strain curve of sheet metal by bulge test. The first part of the paper describes a methodology recently developed by the authors, for effective and accurate determination of stress-strain curve by bulge test. This methodology is based on the continuous measurement of hydraulic pressure and polar height of the specimen during the test, and on an analytical approach that is able to take into account the non-uniformity of the specimen thickness in the meridian section during bulging. Further the FE -simulation of bulge test is used in order to evaluate the accuracy of the hardening law obtained using the new methodology. This evaluation is done by comparison between the FE- simulation results and experimental data. As comparable results were used the distribution of the specimen high and the distribution of the wall thinning as function of the position in the meridian section. The experiments were performed on samples made from rolled steel sheets DC04 using a 3D optical measurement system ARAMIS. By comparison of the results a good agreement between finite element simulation data and experimental result was found.Key words: Bulge test, Analytical approach, Stress-strain curve, Thickness reduction, FE-Simulation.
Banabic, D., Sheet Metal Forming Processes, Constitutive Modelling and Numerical Simulation, Berlin Heidelberg: Springer-Verlag, pp. 157-158, 2010.
Hill, R., A theory of the plastic bulging of a metal diaphragm by lateral pressure, Phil. Magazine 7, pp. 1133-1142, 1950.
Panknin, W., The hydraulic bulge test and the determination of the flow stress curves, Ph.D. Thesis, University of Stuttgart, 1959 (in German).
Chakrabarty, J., Alexander, J.M., Hydrostatic bulging of circular diaphragms, Strain Analysis Eng. Design 5, pp. 155-161, 1970.
Gologranc, F., Evaluation of the flow stress curve with the continuous hydraulic bulge test, Ph.D. Thesis. University of Stuttgart, 1975 (in German).
Shang, H.M., Shim, V.P.W., A model study of the effect of the size of the die shoulder in hydroforming, J. Mech. Working Techn. 10, pp. 307-323, 1984.
Atkinson, M., Accurate determination of biaxial stress-strain relationship from hydraulic bulging tests of sheet metal, Int. J. Mech. Sci. 39, pp. 761-769, 1997.
Kruglov, A.A., Enikeev, F.U., Lutfullin, R.Y., Superplastic forming of a spherical shell out a welded envelope, Mat. Sci. Eng. A323, pp. 416–426, 2002.
Banabic, D., Bălan, T., Comşa, D.S., Closed-form solution for bulging through elliptical dies, J. of Materials Proc. Techn. 115, pp. 83-86, 2001.
Vulcan, M., Siegert, K., Banabic, D., The Influence of Pulsating Strain Rates on the Superplastic Deformation Behaviour of Al-Alloy AA5083 Investigated by Means of Cone Test, Materials Science Forum Vols. 447-448, pp. 139-144, 2004.
Banabic, D., Vulcan, M., Bulge Testing under Constant and Variable Strain Rates of Superplastic Aluminium Alloys, Annals of CIRP 54, pp. 205-209, 2005.
Lăzărescu, L., Comşa, D.S., Banabic, D., Analytical and experimental evaluation of the stress-strain curves of sheet metals by hydraulic bulge tests, Key Engineering Materials Vol. 473, pp. 352-359, Trans Tech Publications, Switzerland, 2011.
Lăzărescu, L., Comşa, D.S., Banabic, D., Determination of Stress-Strain Curves of Sheet Metals by Hydraulic Bulge Test, paper submitted to the 14th International ESAFORM Conference on Material Forming ESAFORM 2011, Queen's University Belfast, UK, 27-29 April, 2011.
Koç, M., Billur, E., Cora, Ö.N., An experimental study on the comparative assessment of hydraulic bulge test analysis methods, Materials & Design 32, pp. 272-281, 2011.
LS-DYNA, Theory Manual, Livermore Software Technology Corporation, Livermore, California, ISBN 0-9778540-0-0, March 2006.
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