Journal of Science and Technology of Composites

Journal of Science and Technology of Composites

Statistical investigation and analysis of the effects of pin diameter, polyurethane layer thickness, and hardness on the forming limit diagram of aluminum/copper bimetallic sheets in the multi-point forming process

Document Type : Research Paper

Authors
Milad Aali MajidAbad
Ramin Hashemi
Habibolah Akbari
School of Mechanical Engineering, Iran University of Science and Technology, Tehran, Iran.
10.22068/jstc.2026.2078995.1943
Abstract
In this study, the forming limit diagram (FLD) of aluminum/copper bimetallic sheets in the multi-point forming (MPF) process was obtained both experimentally and theoretically using the second derivative method. The experimental results showed less than 10% deviation from the theoretical predictions. In the numerical simulations, the effects of pin diameter, polyurethane layer hardness, and polyurethane layer thickness on the forming limit of the MPF process were systematically analyzed. The simulation outputs were subjected to statistical evaluation, and the results indicated a strong correlation among the studied parameters, confirming the adequacy of the selected modeling approach. The findings showed that a pin diameter of 12 mm provided the optimal configuration, yielding the highest forming limit under all polyurethane layer conditions compared to other pin diameters. Furthermore, for all pin sizes, increasing both the hardness and thickness of the polyurethane layer led to an improvement in the forming limit. However, the influence of layer thickness was found to be more significant, particularly for pin diameters of 8 mm and 15 mm.
Keywords
Multi points forming (MPF)
Forming limit diagram (FLD)
Al/Cu Bimetallic Sheets
Nakazima test
Sheet metal forming
Subjects
[1] Walczyk, D. F., Lakshmikanthan, J., Kirk, D. R., “Development of a reconfigurable tool for forming aircraft body panels,” J. Manuf. Syst., vol. 17, no. 4, pp. 287–296, 1998.
[2] Tan, F. X., Li, M. Z., Cai. Z. Y., “Research on the process of multi-point forming for the customized titanium alloy cranial prosthesis,” J. Mater. Process. Technol., vol. 187, pp. 453–457, 2007.
[3] Li, M., Liu, Y., Su, S., Li, G., “Multi-point forming: a flexible manufacturing method for a 3-d surface sheet,” J. Mater. Process. Technol., vol. 87, no. 1–3, pp. 277–280, 1999.
[4] Liu, Y., Li, M., Ju, F., “Research on the process of flexible blank holder in multi-point forming for spherical surface parts,” Int. J. Adv. Manuf. Technol., vol. 89, no. 5–8, pp. 2315–2322, 2017.
[5] Neama, R. A., Al-Baghdadi, M. A. R. S., Al-Waily, M., “Effect of Blank Holder Force and Punch Number on the Forming Behavior of Conventional Dies,” Int. J. Mech. Mechatronics Eng., vol. 18, no. 04, 2018.
[6] Haas, E., Schwarz, R. C., Papazian, J. M., “Design and test of a reconfigurable forming die,” J. Manuf. Process., vol. 4, no. 1, pp. 77–85, 2002.
[7] Li, M.-Z., Cai, Z.-Y., Sui, Z., Yan, Q. G., “Multi-point forming technology for sheet metal,” J. Mater. Process. Technol., vol. 129, no. 1–3, pp. 333–338, 2002.
[8] Cai, Z.-Y., Wang, S.-H., Li, M.-Z., “Numerical investigation of multi-point forming process for sheet metal: wrinkling, dimpling and springback,” Int. J. Adv. Manuf. Technol., vol. 37, no. 9, pp. 927–936, 2008.
[9] Zhang, Q., Wang, Z. R., Dean, T. A., “Multi-point sandwich forming of a spherical sector with tool-shape compensation,” J. Mater. Process. Technol., vol. 194, no. 1–3, pp. 74–80, 2007.
[10] Sun, G., Li, M. Z., Yan, X. P., Zhong, P. P., “Study of blank-holder technology on multi-point forming of thin sheet metal,” J. Mater. Process. Technol., vol. 187, pp. 517–520, 2007.
[11] Chen, J.-J., Li, M.-Z., Liu, W., Wang, C.-T., “Sectional multipoint forming technology for large-size sheet metal,” Int. J. Adv. Manuf. Technol., vol. 25, no. 9, pp. 935–939, 2005.
[12] Cai, Z.-Y., Wang, S.-H., Xu, X.-D., Li, M.-Z., “Numerical simulation for the multi-point stretch forming process of sheet metal,” J. Mater. Process. Technol., vol. 209, no. 1, pp. 396–407, 2009.
[13] Abosaf, M., Essa, K., Alghawail, A., Tolipov, A., Su, S., Pham, D., “Optimisation of multi-point forming process parameters,” Int. J. Adv. Manuf. Technol., vol. 92, no. 5–8, pp. 1849–1859, 2017.
[14] Fang, C., Zhao, J., Ling, L., Wang, W., Wan, M., “Electromagnetic peening-a novel sheet metal forming method,” EasyChair, 2019.
[15] Panuoiu, V., Boazu, D., “Hydro-multipoint Forming, a Challenge in Sheet Metal Forming,” in International Conference on Advanced Manufacturing Engineering and Technologies, Springer, 2017, pp. 79–94.
[16] Erhu, Q., Mingzhe, L., Rui, L., Mingyang, C., Jianlei, L., “Research on formability in multi-point forming with different elastic pads,” Int. J. Adv. Manuf. Technol., vol. 98, no. 5, pp. 1887–1901, 2018.
[17] Abbas, T. F., Younis, K. M., kadhim Mansor, K., “The Influence of Process Parameters on Thickness Distribution in Multipoint Forming Process Using Finite Element Analysis,” in 2019 2nd International Conference on Electrical, Communication, Computer, Power and Control Engineering (ICECCPCE), IEEE, 2019, pp. 120–125.
[18] Alaie, A., Hashemi, R., Kazemi, F., “Investigation of forming limit diagram and mechanical properties of the bimetallic Al/Cu composite sheet at different temperatures which fabricated by explosive welding,” Proc. Inst. Mech. Eng. Part B J. Eng. Manuf., vol. 235, no. 1–2, pp. 73–84, 2021.
[19] Ghazanfari, A., Soleimani, S. S., Keshavarzzadeh, M., Habibi, M., Assempuor, A., Hashemi, R., “Prediction of FLD for sheet metal by considering through-thickness shear stresses,” Mech. Based Des. Struct. Mach., vol. 48, no. 6, pp. 755–772, 2020.
[20] Hashemi, R., Karajibani, E., “Forming limit diagram of Al-Cu two-layer metallic sheets considering the Marciniak and Kuczynski theory,” Proc. Inst. Mech. Eng. Part B J. Eng. Manuf., vol. 232, no. 5, pp. 848–854, 2018.
[21] Majidabad, M. A., Khodayari, R., Akbari, H., Davoodi, B., Hashemi, R., “Multipoint forming process of aluminum sheet considering its forming limit diagram: Experimental and numerical investigations,” Proc. Inst. Mech. Eng. Part L J. Mater. Des. Appl., vol. 0, no. 0, p. 14644207241276680, doi: 10.1177/14644207241276681.
Journal of Science and Technology of Composites
Volume 12, Issue 3
Autumn 2025
Pages 2831-2838