Keywords: numerical simulation, tubular hydroforming, hydroforming technology, tailor-welded blanks, weld line, shell elements.

The implementation of modern lightweight construction concepts results in a specification that emphasises the aspects of the uniform forming of large-scale parts as well as complex local geometric details. The importance of implementing closed section structures in vehicle design is as a result of their higher stiffness-to-weight ratio in bending and torsional loading as compared to open section structures.

Among the techniques used for the aluminium forming in the automotive industry, the one that offers most possibilities for innovation and economic gains relates to the hydroforming tubular forming method [1,2,3,5]. The process consists of the use of hydraulic pressure to expand a pre-formed tubular metal section within the confines of a die cavity. The creation of closed box sections, without the need for secondary joining and reduction in part count through component integration, constitutes inherent advantages of the technology. It is worth noting the outstanding superficial quality obtained in the final products, as a result of the elimination of friction between the parts involved [6].

In this paper the hydroforming simulation is revisited and new developments are shown, focusing on the main features of the forming of tailor-welded blanks [4]. Numerical investigations of tubular hydroforming processes, starting from tailor-welded tubes based on one butt welded joint (with a common diameter and different thickness), are carried out.

1

R.A. Fontes Valente, R.M. Natal Jorge, R.P.R. Cardoso, J.M.A. César de Sá, J.J. Grácio, "Enhanced Strain Shell Elements for Simulation of Hydroforming Processes", COMPLAS 2003, Barcelona, 2003.

2

R.A. Fontes Valente, R.J. Alves de Sousa, M. Parente, R.M. Natal Jorge, J.M.A. César de Sá, J.J. Grácio, "Enhanced Assumed Strain Shell and Solid- Shell Elements: Application in Sheet Metal Forming Processes", accepted for publication on Numiform 2004, Ohio, USA, 2004.

3

S. Novotny, P. Hein, "Hydroforming of sheet metal pairs from aluminium alloys", Journal of Materials Processing Technology, 115, 65-69, 2001. doi:10.1016/S0924-0136(01)00766-X

4

Y. Choi, Y. Heo, H.Y. Kim, D. Seo, "Investigations of weld-line movements for the deep drawing process of tailor welded blanks", Journal of Materials Processing Technology, 108, 1-7, 2000. doi:10.1016/S0924-0136(00)00536-7

5

R.A. Fontes Valente, R.J. Alves de Sousa, M. Parente, R.M. Natal Jorge, J.M.A. César de Sá, J.J. Grácio, "Enhanced Assumed Strain Shell and Solid- Shell Elements: Application in Sheet Metal Forming Processes", accepted for publication on Numiform 2004, Ohio, USA, 2004.

6

M. Ahmetoglu, K. Sutter, X. J. Li, T. Altan, "Tube hydroforming: current research, applications and need for training", J. of Mat. Proc. Technology, 98:224-231, 2000. doi:10.1016/S0924-0136(99)00203-4

purchase the full-text of this paper (price £20)

go to the previous paper
go to the next paper
return to the table of contents
return to the book description
purchase this book (price £95 +P&P)