Effect of Strain-Rate on Forming Limit Strain of Aluminum Alloy and Mild Steel Sheets Under Strain Path Change
Minoru Yamashita*,, Shohei Komuro**, and Makoto Nikawa*
*Department of Mechanical Engineering, Faculty of Engineering, Gifu University
1-1 Yanagido, Gifu-shi, Gifu 501-1193, Japan
**Department of Materials Science and Processing, Graduate School of Natural Science and Technology, Gifu University, Gifu, Japan
The aim of this study is to show the effect of the strain-rate on the forming limit strain of an aluminum alloy A5052 sheet and a mild steel sheet SPCC. Biaxial stretching test was carried out. The prescribed strain path was linear path or that with directional change in straining. The sheet was pre-strained by uniaxial tension in the latter path. The deformation speed was set to be quasi-static or high speed whose strain-rate was about 300 /s using the dedicated high speed stretching device. The forming limit strain of the A5052 sheet for the linear strain path was larger in the high speed stretching than that under the quasi-static condition. For the case with strain path change the forming limit strain was further large. This may be due to the softening phenomenon which occurs by aging treatment, because the stretching experiment was conducted about two weeks after the pre-straining operation. On the other hand, the forming limit strain of the SPCC under the high speed condition was smaller than that under the quasi-static condition in the linear strain path. This is attributed to the decreased strain hardening exponent when the strain-rate increases. Further, in the equi-biaxial stretching of the pre-strained specimen, large difference of the forming limit strain between the deformation speeds was found. It is concluded that A5052 aluminum alloy sheet has a good adaptability to high speed forming, on the other hand, attention should be paid in increasing the forming speed of SPCC.
-  Z. Marciniak and K. Kuczyński, “Limit Strains in The Processes of Stretch-Forming Sheet Metal,” Int. J. of Mechanical Sciences, Vol.9, pp. 609-620, 1967.
-  S. Stören and J. R. Rice, “Localized Necking in Thin Sheets,” J. of Mechanics Physics and Solids, Vol.23, pp. 421-441, 1975.
-  J. R. Rice, “The Elastic-Plastic Mechanics of Crack Extension,” Int. J. of Fracture Mechanics, Vol.4, pp. 41-47, 1968.
-  S. Bruschi, T. Altan, D. Banabic, P. F. Bariani, A. Brosius, J. Cao, A. Ghiotti, M. Khraisheh, M. Merklein, and A. E. Tekkaya, “Testing and Modelling of Material Behaviour and Formability in Sheet Metal Forming,” CIRP Annals – Manufacturing Technology, Vol.63, pp. 727-749, 2014.
-  P. W. Beaver, “Localized Thinning, Fracture and Formability of Aluminium Sheet Alloys in Biaxial Tension,” J. of Mechanical Working Technology, Vol.7, pp. 215-231, 1982.
-  X. Chu, L. Leotoing, D. Guines, and E. Ragneau, “Temperature and Strain Rate Influence on AA5086 Forming Limit Curves: Experimental Results and Discussion on The Validity of The M-K Model,” Int. J. of Mechanical Sciences, Vol.78, pp. 27-34, 2014.
-  C. Zhang, X. Chu, D. Guines, L. Leotoing, J. Ding, and G. Zhao, “Effects of Temperature and Strain Rate on The Forming Limit Curves of AA5086 Sheet,” Procedia Engineering, Vol.81, pp. 772-778, 2014.
-  T. Naka and F. Yoshida, “Deep Drawability of Type 5083 Aluminium – Magnesium Alloy Sheet under Various Conditions of Temperature and Forming Speed,” J. of Materials Processing Technology, Vols.89-90, pp. 19-23, 1999.
-  M. Jie, C. H. Cheng, L. C. Chan, and C. L. Chowa, “Forming Limit Diagrams of Strain-Rate-Dependent Sheet Metals,” Int. J. of Mechanical Sciences, Vol.51, pp. 269-275, 2009.
-  T. Obikawa and T. Sekine, “Fabrication of Miniature Shell Structures of Stainless Sheet Foil and Their Forming Limit in Single Point Incremental Microforming,” Int. J. Automation Technol., Vol.7, No.3, pp. 256-261, 2013.
-  W. Volk, H. Hoffmann, J. Suh, and J. Kim, “Failure Prediction for Nonlinear Strain Paths in Sheet Metal Forming,” CIRP Annals – Manufacturing Technology, Vol.61, pp. 259-262, 2012.
-  O. Fakir, L. Wang, D. Balint, J. P. Dear, and J. Lin, “Predicting Effect of Temperature, Strain Rate and Strain Path Changes on Forming Limit of Lightweight Sheet Metal Alloys,” Procedia Engineering, Vol.81, pp. 736-741, 2014.
-  L. Leotoing and D. Guines, “Investigations of The Effect of Strain Path Changes on Forming Limit Curves Using an In-Plane Biaxial Tensile Test,” Int. J. of Mechanical Sciences, Vol.99, pp. 21-28, 2015.
-  S. Dharaa, S. Basaka, S. K. Panda, S. Hazrab, B. Shollock, and R. Dashwood, “Formability Analysis of Pre-Strained AA5754-O Sheet Metal Using YLD96 Plasticity Theory: Role of Amount and Direction of Uni-Axial Pre-Strain,” J. of Manufacturing Processes, Vol.24, pp. 270-282, 2016.
-  B. Meng, Y. Y. Zhang, C. Cheng, J. Q. Han, and M. Wan, “Effect of Plastic Anisotropy on Microscale Ductile Fracture and Microformability of Stainless Steel Foil,” Int. J. of Mechanical Sciences, Vol.148, pp. 620-635, 2018.
-  H. Taoka, H. Nobuta, H. Meguri, and Y. Kageyama, “Optimization of Motion in High-Speed Servo Press Line,” Int. J. Automation Technol., Vol.4, No.5, pp. 439-446, 2010.
-  K. Wang, J. E. Carsley, B. He, J. Li, and L. Zhang, “Measuring Forming Limit Strains with Digital Image Correlation Analysis,” J. of Materials Processing Technology, Vol.214, pp. 1120-1130, 2014.
-  R. Smerd, S. Winkler, C. Salisbury, M. Worswick, D. Lloyd, and M. Finn, “High Strain Rate Tensile Testing of Automotive Aluminum Alloy Sheet,” Int. J. of Impact Engineering, Vol.32, pp. 541-560, 2005.
-  M. Yamashita, M. Gotoh, and E. Fujita, “Development of Drop-Hammer Tension Apparatus with Controlled Stopping Device and High Rate Tension Test,” Proc. Int. Conf. of Materials and Mechanics, pp. 83-88, 1997.
-  A. Graf and W. Hosford, “The Influence of Strain-Path Changes on Forming Limit Diagrams of A1 6111 T4,” Int. J. of Mechanical Sciences, Vol.36, No.10, pp. 897-910, 1994.
-  T. Tanabe and S. Yamamoto, “Explanation of Solid Solution Hardening (Softening), Age-Hardening (Softening) and Work Hardening (Softening) Based on Chemical Bonds,” Proc. 12th Int. Conf. Aluminium Alloys, pp. 2252-2257, 2010.
-  M. Howeyze, A. R. Eivani, H. Arabi, H. R. Jafarian, and N. Park, “The Effect of Amount of Pre-Strain Using Equal Channel Angular Pressing on Softening Response of AA5052 alloy,” J. of Material Research Technology, Vol.9, No.3, pp. 6682-6695, 2020.
-  T. Murakami, M. Yamamoto, A. Kamio, and T. Takahashi, “Changes and Anisotropy in Tensile Properties of Rolled A-Mg Alloys during Long Term Aging,” Light Metal, Vol.40, No.7, pp. 538-542, 1990 (in Japanese).
-  J. H. Percy, “The Effect of Strain Rate on the Forming Limit Diagram for Sheet Metal,” Annals of the CIRP, Vol.29, pp. 151-152, 1980.