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### Comparison of numerical models for hydroforming of X-shapes

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Identyfikatory
Warianty tytułu
PL
Porównanie modeli numerycznych stosowanych w modelowaniu stosowanych w modelowaniu hydromechanicznego kształtowania czwórników
Konferencja
14th KomPlasTech Conference, Zakopane, January 14-17, 2007
Języki publikacji
EN
Abstrakty
EN
Hydroforming could be regarded as one of the most advanced and complicated process of metal forming. The common way of hydroforming is to deform sheet metal or tube by means of fluid pressure. By this way some products of very complicated shapes could be obtained. The hydroforming is very useful for producing whole components that would otherwise be made from multiple stampings joined together. For example, such shapes are difficult or impossible to produce by another processes like welding or casting. Hydroforming processes are usually associated with very high strains which lead to failures commonly observed in sheet metal forming, e.g. fracture or wrinkling. These failures are difficult to avoid by designing the process in a traditional way and finding the process parameters by trial and error method. Recently numerical modeling has proved to be a powerful tool for development of hydroforming processes. Hydroforming has been considered as a kind of sheet metal forming process. Majority of numerical models for sheet metal forming has been based on 2D geometry and shell elements in order to simplify the calculations. In this paper, there have been presented both 3D-shell and 3D-solid models for numerical modeling of hydroforming of copper X-shapes. This process has been chosen because of many difficulties in finding proper process parameters by a common designing way. The X-joint hydroforming is conducted to bulge a cylindrical tube with internal pressure and axial load using the displacement of the compressing punches. Proper process parameters, i.e. internal pressure and axial feeding, allow to obtain an X-shape without failures. If internal pressure is too high, the bursting will occur. On th other hand, if the axial feeding force is too high then the wrinkling of the tube will occur. There have been performed experimental tests on hydroforming of X-shapes. Tubular copper blanks with the initial outer diameter 22 mm and the wall thickness 1 mm were used to make X-shapes. A straight tube blank of 120 mm in the length was placed and restrained in the die that determined the final shape of the component. The tube was sealed at the ends by the axial punches. As the velocities of the left and right axial punches were kept constant during deformation process, then the axial feeding force was a result of deformation resistance of a tube blank. On the other hand, the internal pressure was changing according to specified internal pressure versus punch displacements curve. The computer simulations of hydroforming of X-shapes were made using MSC.MARC software. The geometrical models and process parameters corresponded with experimental ones. There were created two numerical models. 3D-membrane/shell elements describing hydroformed tube were used in the first model. Second model was built with typical 3D-solid elements. The results of computer simulations have been compared with the results of experiments. Both 3D-shell and 3D-solid models have provided quite high accuracy in getting the X-shape geometry for various process parameters. However, only 3-D model has been useful to analyse thickness distribution in X-shapes. The calculated stress and strain states as well as thickness ditributions have been taken into account to analyse failures occuring during hydroforming.
PL
Modelowanie komputerowe jest bardzo pomocne w rozwoju procesów kształtowania hydromechanicznego. Dotychczas stosowano różnorodne modele numeryczne, ale wobec braku porównań trudno było ocenić ich przydatność do modelowania poszczególnych procesów. W referacie przedstawiono wykorzystanie modeli 3D-shelI oraz 3D-solid do modelowania hydromechanicznego kształtowania czwórników z miedzi. Wyniki obliczeń porównano z wynikami doświadczeń. Uzyskano bardzo dużą dokładność obliczeń dla obydwu modeli przy wyznaczaniu kształtu czwórników dla różnych parametrów procesu. Jednakże to model 3D-solid okazał się znacznie lepszy i dokładniejszy przy analizie rozkładu grubości ścianek czwórników i historii obciążenia.
Słowa kluczowe
EN
Wydawca
Czasopismo
Rocznik
Strony
294--298
Opis fizyczny
Bibliogr. 9 poz., rys.
Twórcy
autor
autor
• Institute of Materials Processing, Warsaw University of Technology Narbutta 85, 02-524 Warsaw, Poland
Bibliografia
• Aydemir, A., Vree J.H.P., Brekelmans, W.A.M., Geers, M.G.D., Sillekens, W.H., Werkhoven, R.J., 2005, An adaptive simulation approach designed for tube hydroforming processes, J. Mat. Proc. Techn., 159, 303-310.
• Hama, T., Ohkubo, T., Kurisu, K., Fujimoto, H., Takuda, H., 2006, Formability of tube hydroforming under various loading paths, J. Mat. Proc. Techn., 177, 676-679.
• Jirathearanat, S., Hartl, Ch., Altan, T., 2004, Hydroforming of Y-shapes - product and process design using FEA simulation and experiments, J. Mat. Proc. Techn., 146, 124-129.
• Kim, T.J., Yang, D.Y., Han, S.S., 2004, Numerical modeling of the multi-stage sheet pair hydroforming process, J. Mat. Proc. Techn., 151,48-53.
• Mac Donald, B.J., Hashimi, M.S.J., 2001, Tree-dimensional finite element simulation of bulge forming using a solid bulging medium, Finite Element in Analysis and Design, 37, 107-116.
• Mac Donald, B.J., Hashimi, M.S.J., 2000, Finite element simulation of bulge forming of a cross-joint from tubular blank, J. Mat. Proc. Techn., 103, 333-342.
• Plancak, M., Vollertsen, F., Woitschig, J., 2005, Analysis, finite element simulation and experimental investigation of friction in tube hydroforming, J. Mat. Proc. Techn., 170, 220-228.
• Ray, P., Mac Donald, B.J., 2004, Determination of the optimal load path for tube hydroforming processes using a fuzzy load control algorithm and finite element analysis, Finite Elements in Analysis and Design, 41, 173-192.
• Zadeh, H.K., Mashhadi, M.M., 2006, Finite element simulation and experiment in tube hydroforming of unequal T shapes, J. Mat. Proc. Techn., 177, 684-687.
Typ dokumentu
Bibliografia