Forming of Multiple Straight Convex Shapes on Aluminum Sheet Using Impulsive Water Pressure
Minoru Yamashita*,, Haruki Saito**, and Makoto Nikawa*
*Department of Mechanical Engineering, Gifu University
1-1 Yanagido, Gifu-shi, Gifu 501-1193, Japan
**Graduate School of Natural Science and Technology, Gifu University, Gifu, Japan
Several types of multiple straight convex shapes were formed on a thin aluminum sheet with a grooved die using impulsive water pressure. The maximum pressure was 160 MPa in the high-speed forming, wherein a drop hammer testing machine was used, whereas it was 100 MPa in the low-speed forming because of the limitations of the press machine. The effects of the forming speed, cross-sectional shape, and pitch of the grooves on the deformation behavior were investigated. The increase in the impulsive water pressure was found to be affected significantly by the compressibility of water. The symmetricity of the convex shape in the cross-section decreased at both ends for a smaller pitch because of the imbalance of the material flow at both peripheries of the groove. The concave surface profile of the pressure side was more rounded in the high-speed forming than that in the low-speed forming when semicircular and rectangular grooved dies were used. This may be attributed to the fact that the plastic deformation becomes more uniform owing to the positive strain rate sensitivity of the test material. In the forming with rectangular grooves, fracture occurred under the low- and high-speed conditions, wherein the maximum pressure was set to 100 MPa. However, the material did not fracture during high-speed forming with a pressure of 160 MPa, where the convex shape was higher and the material contacted the bottom of the groove. This behavior may be because the dislocation density of the material did not increase rapidly owing to the strain rate being maintained high until the material suddenly stopped deforming in the latter condition. In forming with a trapezoidal grooved die, the formed profiles were considerably similar under all conditions because the strain was considerably smaller than that with the other grooves.
-  J. C. Hung and C. C. Lin, “Fabrication of micro-flow channels for metallic bipolar plates by a high-pressure hydroforming apparatus,” J. of Power Sources, Vol.206, pp. 179-184, 2012.
-  H. Kargar-Pishbijari, S. J. Hosseinipour, and H. Jamshidi Aval, “A novel method for manufacturing microchannels of metallic bipolar plate fuel cell by the hot metal gas forming process,” J. of Manufacturing Processes, Vol.55, pp. 268-275, 2020.
-  M. Soltanpour, A. Fazli, and R. J. Niaraki, “High speed hydroforming and direct quenching: An alternative method for production of hot stamped parts with high productivity,” Procedia Engineering, Vol.207, pp. 317-322, 2017.
-  M. Elyasi, F. A. Khatir, and M. Hosseinzadeh, “Manufacturing metallic bipolar plate fuel cells through rubber pad forming process,” Int. J. of Advanced Manufacturing Technology, Vol.89, pp. 3257-3269, 2017.
-  Y. Liu and L. Hua, “Fabrication of metallic bipolar plate for proton exchange membrane fuel cells by rubber pad forming,” J. of Power Sources, Vol.195, pp. 3529-3535, 2010.
-  L. Peng, P. Hua, X. Lai, D. Mei, and J. Ni, “Investigation of micro/meso sheet soft punch stamping process – simulation and experiments,” Materials & Design, Vol.30, pp. 783-790, 2009.
-  S. S. Lim, Y. T. Kim, and C. G. Kang, “Fabrication of aluminum 1050 micro-channel proton exchange membrane fuel cell bipolar plate using rubber-pad-forming process,” Int. J. of Advanced Manufacturing Technology, Vol.65, pp. 231-238, 2013.
-  C. Zhang, J. Ma, X. Liang, F. Luo, R. Cheng, and F. Gong, “Fabrication of metallic bipolar plate for proton exchange membrane fuel cells by using polymer powder medium based flexible forming,” J. of Materials Processing Technology, Vol.262, pp. 32-40, 2018.
-  V. Modanloo, H. Talebi-Ghadikolaee, V. Alimirzaloo, and M. Elyasi, “Fracture prediction in the stamping of titanium bipolar plate for PEM fuel cells,” Int. J. of Hydrogen Energy, Vol.46, pp. 5729-5739, 2021.
-  S. Mahabunphachai, O. N. Cora, and M. Koc, “Effect of manufacturing processes on formability and surface topography of proton exchange membrane fuel cell metallic bipolar plates,” J. of Power Sources, Vol.195, pp. 5269-5277, 2010.
-  J. R. Mawdsley, J. D. Carter, X. Wang, S. Niyogi, C. Q. Fan, R. Koc, and G. Osterhoutd, “Composite-coated aluminum bipolar plates for PEM fuel cells,” J. of Power Sources, Vol.231, pp. 106-112, 2013.
-  M. Yamashita, S. Komuro, and M. Nikawa, “Effect of strain-rate on forming limit strain of aluminum alloy and mild steel sheets under strain path change,” Int. J. Automation Technol., Vol.15, No.3, pp. 343-349, 2021.
-  K. Nakamura, H. Koresawa, and H. Narahara, “One action press forming of helix bevel gear by using multi-cylinder press and die heating system,” Int. J. Automation Technol., Vol.12, No.5, pp. 767-774, 2018.
-  H. Taoka, H. Nobuta, H. Meguri, and Y. Kageyama, “Optimization of motion control in high-speed servo press line,” Int. J. Automation Technol., Vol.4, No.5, pp. 439-446, 2010.
-  J. M. Lifshitz and H. Leber, “Data processing in the split Hopkinson pressure bar tests,” Int. J. of Impact Engineering, Vol.15, pp. 723-733, 1994.
-  U. S. Lindholm, R. L. Bessey, and G. V. Smith, “Effect of strain rate on yield strength, tensile strength, and elongation of three aluminum alloys,” J. of Materials, Vol.6, pp. 119-133, 1971.
-  C. Fressengeas and A. Molinari, “Inertia and thermal effects on the localization of plastic flow,” Acta Metallurgica, Vol.33, pp. 387-396, 1985.
-  S. K. Samanta, “Dynamic deformation of aluminum and copper at elevated temperatures,” J. of Mechanics and Physics of Solids, Vol.19, pp. 117-135, 1971.
-  S. Tanimura, H. Hayashi, T. Yamamoto, and K. Mimura, “Dynamic tensile properties of steels and aluminum alloy for a wide range of strain rates and strain,” J. of Solid Mechanics and Materials Engineering, Vol.3, pp. 1263-1273, 2009.
-  E. Chu, “Effect of strain rate sensitivity on FLDs – An Instability approach,” Int. J. of Mechanical Sciences, Vol.64, pp. 273-279, 2012.
-  J. W. Hutchinson, “Influence of strain-rate sensitivity on necking under uniaxial tension,” Acta Metallurgica, Vol.25, pp. 839-846, 1977.
-  X. Hu and G. S. Daehn, “Effect of velocity on flow localization in tension,” Acta Materialia, Vol.44, pp. 1021-1033, 1996.
-  G. Ubertalli, P. Matteis, S. Ferraris, C. Marciano, F. D’Aiu, M. M. Tedesco, and D. D. Caro, “Strain rate behavior of aluminum alloy for sheet metal forming processes,” Metals, Vol.10, 242, 2020.
-  M. Li and A. Chandra, “Influence of strain-rate sensitivity on necking and instability in sheet metal forming,” J. of Materials Processing Technology, Vol.96, pp. 133-138, 1999.
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