Effect of Friction Models on Stress Distribution of Sheet Materials during V-Bending Process

In a metal forming process, the friction between the material and the tools influences the process by modifying the stress distribution of the workpiece. This frictional behaviour is often taken into account by using a constant coefficient of friction in the finite element simulations of sheet metal forming processes. However, friction coefficient varies in time and space with many parameters. The Stribeck friction model is investigated in this study to predict springback behaviour of AA6061-T4 sheets during V-bending process. The coefficient of friction in Stribeck curve depends on sliding velocity and contact pressure. The plane-strain bending process is simulated in ABAQUS/Standard. We compared the computed punch load-stroke curves and springback related to the constant coefficient of friction with the defined friction model. The results clearly showed that the new friction model provides better agreement between experiments and results of numerical simulations. The influence of friction models on stress distribution in the workpiece is also studied numerically

Authors:

• Maziar Ramezani
• Zaidi Mohd Ripin

Keywords:

• Friction model
• Stress distribution
• V-bending.

References:

[1] J. R. Duflou, J. Vancza , R. Aerens, "Computer aided process planning
for sheet metal bending A state of the art", Computers in Industry, vol.
56, 2005, pp. 747-771.
[2] M. Ramezani, Z. M. Ripin, R. Ahmad, "Modelling of kinetic friction in
V-bending of ultra-high-strength steel sheets", International Journal of
Advanced Manufacturing Technology, 2008, doi: 10.1007/s00170-008-
1450-4.
[3] W. D. Carden, L. M. Geng, D. K. Matlock, R. H. Wagoner,
"Measurement of springback", International Journal of Mechanical
Sciences, vol. 44, 2002, pp. 79-101.
[4] M. Firat, "U-channel forming analysis with an emphasis on springback
deformation", Materials and Design, vol. 28, 2007, pp. 147-154.
[5] M. Ramezani, Z. M. Ripin, R. Ahmad, "Computer-aided modelling of
friction in rubber-pad forming process", Journal of Materials Processing
Technology, 2009, doi:10.1016/j.jmatprotec.2009.01.015.
[6] A. Matuszak, "Factors influencing friction in steel sheet forming",
Journal of Materials Processing Technology, vol. 106, 2000, pp. 250-
253.
[7] F. H. Lin, A. A. Tseng, "A finite element analysis of elasto-plastic
contact problems in metal forming", Materials and Design, vol. 19,
1998, pp. 99-108.
[8] W. R, D. Wilson, "Friction and lubrication in bulk metal forming
processes", Journal of Applied Metalworking, vol. 1, 1979, pp. 1-19.
[9] J. A. Schey, "Speed effects in drawbead simulation", Journal of
Materials Processing Technology, vol. 57, 1996, pp. 146-154.
[10] P. K. Saha, W. R. D. Wilson, R. S. Timsit, "Influence of surface
topography on the frictional characteristics of 3104 aluminum alloy
sheet", Wear, vol. 197, 1996, pp. 123-129.
[11] D. J. Schipper, "Transitions in the lubrication of concentrated contacts",
PhD Thesis, University of Twente, the Netherlands, 1988.
[12] X. Lu, M. M. Khonsari, E. R. M. Gelinck, "The Stribeck curve:
experimental results and theoretical prediction", ASME Journal of
Tribology, vol. 128, 2006, pp. 789-794.
[13] E. R. M. Gelink, D. J. Schipper, "Calculation of Stribeck curves for line
contacts", Tribology International, vol. 33, 2000, pp. 175-181.
[14] S. Bair, W. O. Winer, "A Rheological Model for EHL Contacts Based
on Primary Laboratory Data", ASME Journal of Lubrication
Technology, vol. 101, 1979, pp. 258-265.
[15] K. P. Li, W. P. Carden, R. H. Wagoner, "Simulation of springback",
International Journal of Mechanical Sciences, vol. 44, 2002, pp. 103-
122.