Generalised CAD/CAM solution to the three-dimensional off-centric extrusion of shaped sections: analysis

N. R. Chitkara, Kemal Celik

Research output: Contribution to journalArticlepeer-review


An analytical method based on the upper-bound theory is proposed to investigate the three-dimensional off-centric extrusion of arbitrarily shaped sections from arbitrarily shaped billets through linearly converging and smooth curved dies. A set of generalised kinematically admissible velocity fields are derived on the assumption of Bezier-type streamlines that provide compatibility of surface representation with most CAD/CAM systems. To obtain a more realistic non-uniform metal flow, a special velocity function was also incorporated into the derived velocity fields and work hardening effect of the material considered. Based on the method presented, for a given reduction in area, material property, friction condition and off-centric positioning of the exit cross-section, predictions of the deforming grid pattern, curvature of the extruded product as well as upper-bound to the extrusion pressures may be obtained. The above procedure is highlighted and commented upon.

Original languageEnglish (US)
Pages (from-to)273-294
Number of pages22
JournalInternational Journal of Mechanical Sciences
Issue number2
StatePublished - Feb 2000
Externally publishedYes

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering
  • Aerospace Engineering
  • Ocean Engineering
  • Applied Mathematics
  • General Materials Science
  • Civil and Structural Engineering


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