Considering the significance of sheet metal forming in various industries, metal sheets, and lightweight alloys find extensive applications. It is essential to predict the formability limit of sheets. Whereas the previous studies used the Nakazima test, this study aims to determine the forming limit diagram (FLD) numerically and experimentally using multipoint forming, considering the strain path's effect on formability. Also, it is compared with the conventional FLD obtained via the Nakazima test. The results show that multipoint forming improves sheet metal forming. The experimental FLD for an AL 2024-O sheet with a 12 mm pin size was found to have higher formability than that obtained from the Nakazima test. The effect of the polyurethane layer on the forming limit diagram was investigated. The experimental results showed that the polyurethane layer prevents local strain and increases the limits on the forming limit diagram. The numerical forming limit diagram was predicted by the second derivative method. Finally, the experimental results were compared with the numerical simulation results, showing that the results had an agreement above 90%. This method can be used as a reference for assessing the effectiveness of the multipoint forming technique.
HardtDEWebbRDSuhNP. Sheet metal die forming using closed-loop shape control. CIRP Ann1982; 31: 165–169.
2.
WalczykDFLakshmikanthanJKirkDR. Development of a reconfigurable tool for forming aircraft body panels. J Manuf Syst1998; 17: 287–296.
3.
HaasESchwarzRCPapazianJM. Design and test of a reconfigurable forming die. J Manuf Process2002; 4: 77–85.
4.
LiM-ZCaiZ-YSuiZ,et al.Multi-point forming technology for sheet metal. J Mater Process Technol2002; 129: 333–338.
5.
CaiZ-YWangS-HLiM-Z. Numerical investigation of multi-point forming process for sheet metal: wrinkling, dimpling and springback. Int J Adv Manuf Technol2008; 37: 927–936.
6.
TanFXLiMZCaiZY. Research on the process of multi-point forming for the customized titanium alloy cranial prosthesis. J Mater Process Technol2007; 187: 453–457.
7.
ZhangQWangZRDeanTA. Multi-point sandwich forming of a spherical sector with tool-shape compensation. J Mater Process Technol2007; 194: 74–80.
8.
XiangHYLengCJZhongYX. Numerical simulation and experimental method for auto-panel forming defects analysis. Mater Sci Forum2008; 575: 169–173.
9.
SunGLiMZYanXP,et al.Study of blank-holder technology on multi-point forming of thin sheet metal. J Mater Process Technol2007; 187: 517–520.
10.
ChenJ-JLiM-ZLiuW,et al.Sectional multipoint forming technology for large-size sheet metal. Int J Adv Manuf Technol2005; 25: 935–939.
11.
CaiZ-YWangS-HXuX-D,et al.Numerical simulation for the multi-point stretch forming process of sheet metal. J Mater Process Technol2009; 209: 396–407.
12.
AbosafMEssaKAlghawailA, et al.Optimisation of multi-point forming process parameters. Int J Adv Manuf Technol2017; 92: 1849–1859.
13.
FangCZhaoJLingL, et al.Electromagnetic peening-a novel sheet metal forming method EasyChair, 2019.
14.
LiuYLiMJuF. Research on the process of flexible blank holder in multi-point forming for spherical surface parts. Int J Adv Manuf Technol2017; 89: 2315–2322.
15.
NeamaRAAl-BaghdadiMARSAl-WailyM. Effect of blank holder force and punch number on the forming behavior of conventional dies. Int J Mech Mechatronics Eng2018; 18: 56–64.
16.
LeeI-K, et al.Study on hot multi-point forming process with cooling system for Al thick plate by using numerical analysis. Procedia Eng2017; 207: 1165–1169.
17.
PanuoiuVBoazuD. Hydro-multipoint forming, a challenge in sheet metal forming. In International Conference on Advanced Manufacturing Engineering and Technologies, 2017, pp. 79–94.
18.
ErhuQMingzheLRuiL, et al.Research on formability in multi-point forming with different elastic pads. Int J Adv Manuf Technol2018; 98: 1887–1901.
19.
Zareh-DesariBDavoodiBVedaei-SabeghA. Investigation of deep drawing concept of multi-point forming process in terms of prevalent defects. Int J Mater Form2017; 10: 193–203.
20.
KarajibaniEHashemiRSedighiM. Forming limit diagram of aluminum-copper two-layer sheets: numerical simulations and experimental verifications. Int J Adv Manuf Technol2017; 90: 2713–2722.
21.
AbebeMParkJ-WKangB-S. Reliability-based robust process optimization of multi-point dieless forming for product defect reduction. Int J Adv Manuf Technol2017; 89: 1223–1234.
22.
AlfaidiMFXiaoxingLNwirMA. Numerical simulation application in Multi Point Forming. In 2010 The 2nd International Conference on Computer and Automation Engineering (ICCAE), 2010, vol. 2, pp. 502–504.
23.
LiuCLiJDongY, et al.Fracture prediction in the forming of aircraft Al stiffeners using multi-point dies. Int J Adv Manuf Technol2017; 90: 3109–3118.
24.
Zareh-DesariBDavoodiBVedaei-SabeghA. Investigation of deep drawing concept of multi-point forming process in terms of prevalent defects. Int J Mater FormApr. 2017; 10: 193–203.
25.
NasiriSMMBastiAHashemiR,et al.Effects of normal and through-thickness shear stresses on the forming limit curves of AA3104-H19 using advanced yield criteria. Int J Mech Sci2018; 137: 15–23.
26.
ErfanianMHashemiR. A comparative study of the extended forming limit diagrams considering strain path, through-thickness normal and shear stress. Int J Mech Sci2018; 148: 316–326.
27.
JalaliAHashemiRRajabiM,et al.Finite element simulations and experimental verifications for forming limit curve determination of two-layer aluminum/brass sheets considering the incremental forming process. Proc Inst Mech Eng Pt L J Mater Des Appl2022; 236: 361–373.
28.
de AlmeidaLGeraldo SchönC. Evaluation of the formability of 90/10 brass produced by different casting processes and investigation of the effect of Forming Limit Diagram determination procedure. J Mater Res2019; 8: 4163–4172.
29.
HongJ-HYooDKwonYN,et al.Evaluation of rate-dependent forming limit for AA7075 sheets under pneumatic stretching method at elevated temperatures. J Mater Res2023; 22: 1839–1854.
30.
ChengZZhangCWangM, et al.Forming limit analysis of AA5052 sheet under bilinear strain path by designing a novel large-scale gripping fixture. J Mater Res2023; 22: 2425–2439.
31.
HarhashMPalkowskiH. Ncremental sheet forming of steel/polymer/steel sandwich composites. J Mater Res2021; 13: 417–430.
32.
DarabiRAzodiHDBagherzadehS. Investigation into the effect of material properties and arrangement of each layer on the formability of bimetallic sheets. J Manuf Process2017; 29: 133–148.
33.
RoostaeiMDarabiR. Investigation on formability of three-layer joined Al/Cu/Al sheets annealed at different temperature. Mater Sci Technol2020; 36: 1476–1486.
34.
AlavizadehSMShahbazi KaramiJ. Experimental and numerical investigation on metal tubes forming with a novel reconfigurable hydroforming die based on multi-point forming. Int J Adv Manuf Technol2019; 13: 489–500.
