238 Int. J. Manufacturing Technology and Management, Vol. 15, No. 2, 2008 Copyright © 2008 Inderscience Enterprises Ltd. Mechanical stresses in the multilayered T-branch hydroforming: numerical simulation M.D. Islam,* A.G. Olabi and M.S.J. Hashmi School of Mechanical and Manufacturing Engineering, Dublin City University, Dublin 9, Ireland E-mail: Din.islam@cit.ie E-mail: abdul.olabi@dcu.ie E-mail: saleem.hashmi@dcu.ie *Corresponding author Abstract: In the manufacturing process, materials are deformed plastically at a level or lower than the ultimate stress of the materials. In the hydroforming process, the deformation of the material occurs non-linearly and this introduces mechanical stresses which are developed into the final products. This paper describes different kind of mechanical stresses which result from the hydroforming process in a multilayered T-branch simulation. Simulations have been carried out for the multilayered tubes comprising an outer layer of commercial brass and an internal layer of annealed copper. Currently, no classical solution exists for this type of problem. For that reason a numerical analysis has been presented in this paper. Analyses have been carried out under different loading conditions and the allowable stress that is developed in the final products is presented for the top central node and in addition to the overall model. Keywords: hydroforming; simulation; stress. Reference to this paper should be made as follows: Islam, M.D., Olabi, A.G. and Hashmi, M.S.J. (2008) ‘Mechanical stresses in the multilayered T-branch hydroforming: numerical simulation’, Int. J. Manufacturing Technology and Management, Vol. 15, No. 2, pp.238–245. Biographical notes: M.D. Islam graduated from Bangladesh University of Engineering and Technology (BUET) in 2001, under the Department of Mechanical Engineering. He worked in a manufacturing company for a year and a half in Bangladesh. He joined as a Postgraduate research student under the School of Mechanical and Manufacturing Engineering, Dublin City University, for the degree of Master of Engineering in February 2003. He graduated from Dublin City University in November 2005. Now, he is pursuing further research for his PhD in Cork Institute of Technology, Ireland. A.G. Olabi Graduated from Damascus University in 1984. He worked for four years in R&D between 1889 and 1990 on a research project leading to Masters degree in Dublin. Between 1990 and 1993, he was working on a research project leading to PhD in Dublin, between 1994 and 1998, he was lecturing at the Higher Institute of Applied Science and Technology (HIAST) Damascus. He was working at the Research Centre of FIAT on the development of new generation of feeding and injection components between 1999 and 2002. From October 2002, he works at DCU.