Title: Integration of double sheet and tube hydroforming processes: numerical investigation of the feasibility of a complex part

Authors: M. Geiger, M. Cojutti

Addresses: University of Erlangen-Nuremberg, Egerlandstrasse 11, Erlangen 91058, Germany. ' University of Erlangen-Nuremberg, Egerlandstrasse 11, Erlangen 91058, Germany

Abstract: The hydroforming technology undergoes since several years a strong development, mainly due to the possibility to produce components with complex shape and high strength/weight ratio. This has led to a widespread application of the tube hydroforming technology in many industrial sectors, while the application of sheet hydroforming, probably due to a lack of knowledge regarding the optimal control of the process, still encounters some difficulties. This paper presents the results of a feasibility study by FE-analysis of a complex hollow part resulting from the simultaneous hydroforming of two sheets and a tubular component in one tool. The focus is set in particular on the appearance of wrinkling on the two sheets in the tube-sheet transition zone due to an excessive draw-in of material in the tool cavity in the early stages of the forming process. The study presents a model of the wrinkles which allows the evaluation of their sharpness and investigates the effect of the thickness of tube and sheets and of the blankholder force on their appearance and reversibility. Based on the systematic variation of the above mentioned parameters, the behaviour of the steels DC04, DP450 and Trip800 and of the aluminium alloy AA5754 for the sheet pair is studied. For each material, the possibility to define a process window which allows the production of a component free of defects is investigated.

Keywords: tube hydroforming; sheet hydroforming; wrinkling tendency; FEA; finite element analysis; complex parts; hollow parts; forming; sheet steel; aluminium alloys; thickness; blankholder force.

DOI: 10.1504/IJCMSSE.2009.024929

International Journal of Computational Materials Science and Surface Engineering, 2009 Vol.2 No.1/2, pp.110 - 117

Published online: 04 May 2009 *

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