Numerical Analysis on Surface Ductile Fractures for Some Extrusion Conditions

Abstract:

Extrusion processes can be utilized for production of parts characterized by complex shapes; furthermore, nowadays, the market needs are always more driving towards the manufacture of components with thinner thickness for weight and volume reduction. As a consequence, the process complexities are growing up but, nevertheless, quality and productivity have to be guaranteed by companies if they want to survive in an increasingly competitive society.In this work, a ductile criterion was utilized to highlight which variations due to thickness reduction can bring to superficial defects in extruded components. The study was carried out by using a suitable die geometry where thickness changes can be performed keeping constant the other geometrical variables. The die optimization was carried out by numerical simulations which were utilized for homogenizing the extruded velocity at the exit of the bearing zone. Different working conditions were numerically analyzed and geometrical die changes were performed to highlight their influences on the superficial integrity of the extruded parts.

• Periodical: Key Engineering Materials (Volume 585)
• Pages: 51-58
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.585.51
• Online since: December 2013
• Authors: Francesco Gagliardi, Teresa Citrea, Giuseppina Ambrogio, Luigino Filice
• Keywords: Ductile Criterion, Lode Parameter, Surface Defect, Triaxiality

References

[1] M. Bauser, G. Sauer, K. Siegert, Extrusion, The Material Information Society, Dusseldorf, Germany, (2006).

[2] D. Lesniak, W. Libura, Extrusion of sections with varying thickness through pocket dies, Journal of Materials Processing Technology, Vol. 194 (2007), p.38–45.

DOI: 10.1016/j.jmatprotec.2007.03.123

[3] J. Lof, Y. Blokhuis, FEM simulations of the extrusion of complex thin-walled aluminium sections, Journal of Materials Processing Technology, Vol. 122 (2002), p.344–354.

DOI: 10.1016/s0924-0136(01)01266-3

[4] C. Zhanga, G. Zhao, Z. Chena, H. Chen, F. Kou, Effect of extrusion stem speed on extrusion process for a hollow aluminum profile, Materials Science and Engineering B, Vol. 177 (2012), p.1691–1697.

DOI: 10.1016/j.mseb.2011.09.041

[5] J. Zhou, L. Li, J. Duszczyk, Computer simulated and experimentally verified isothermal extrusion of 7075 aluminium through continuous ram speed variation, Journal of Materials Processing Technology, Vol. 146 (2004), p.203–212.

DOI: 10.1016/j.jmatprotec.2003.10.018

[6] L. Li, J. Zhou, J. Duszczyk, Prediction of temperature evolution during the extrusion of 7075 aluminium alloy at various ram speeds by means of 3D FEM simulation, Journal of Materials Processing Technology, Vol. 145 (2004), p.360–370.

DOI: 10.1016/j.jmatprotec.2003.09.003

[7] R. Hölker, A. Jäger, N. Ben Khalifa, A. Erman Tekkaya, New Concepts for Cooling of Extrusion Dies Manufactured by Rapid Tooling, Key Engineering Materials, Vol. 491 (2011), pp.223-230.

DOI: 10.4028/www.scientific.net/kem.491.223

[8] O. Richmond, W.A. Spitzig, Pressure dependence and dilatancy of plastic flow. In: Theoretical and Applied Mechanics, Proc. of the 15th International Congress of Theoretical and Applied Mechanics, Toronto, Canada. North-Holland Publ., Amsterdam, Netherlands, 1980, p.377.

[9] C.D. Wilson, A critical reexamination of classical metal plasticity, Journal of Applied Mechanics, Transactions ASME, Vol. 69 (1) (2002), p.63–68.

[10] A. Needleman, V. Tvergaard, An analysis of ductile rupture in notched bars. Journal of the Mechanics and Physics of Solids, Vol. 32 (6) (1984), p.461–490.

DOI: 10.1016/0022-5096(84)90031-0

[11] Y.N. Li, M. Luo, J. Gerlach, T. Wierzbicki, Prediction of shear-induced fracture in sheet metal forming, Journal of Materials Processing Technology, Vol. 210 (2010), p.1858–1869.

DOI: 10.1016/j.jmatprotec.2010.06.021

[12] Y.S. Lou, H. Huh, S. Lim, K. Pack, New ductile fracture criterion for prediction of fracture forming limit diagrams of sheet metals, International Journal of Solids Structures, Vol. 49 (2012), p.3605–3615.

DOI: 10.1016/j.ijsolstr.2012.02.016

[13] Yanshan Lou, Hoon Huh, Extension of a shear-controlled ductile fracture model considering the stress triaxiality and the Lode parameter, International Journal of Solids and Structures, Vol. 50 (2013), p.447–455.

DOI: 10.1016/j.ijsolstr.2012.10.007

[14] Lode, Versuche Uber den Einfluss der mittleren Hauptspannung auf das Fliessen der Metalle Eisen, Kupfer, und Nickel. Z. Phys, Vol 36 (1926), p.913–939.

DOI: 10.1007/bf01400222

[15] F. Gagliardi, G. Ambrogio, L. Filice, On the die design in AA6082 porthole extrusion, CIRP Annals - Manufacturing Technology, Vol. 61 (1) (2012), p.231–234.

DOI: 10.1016/j.cirp.2012.03.122