Application of an upper bound method to off-centric extrusion of square sections, analysis and experiments

Kemal Celik, N. R. Chitkara

Research output: Contribution to journalArticlepeer-review


In the present study, previously developed analytical approach (Chitkara and Celik) which was based on the upper-bound theory, for the design of three dimensional off-centric extrusion of arbitrarily shaped dies was applied to the off-centric extrusion of square sections from initially round billets with experimental verifications. A computer program was written to obtain optimum die design which yield the lowest upper-bound for a given reduction in area, die length, off-centric positioning and frictional conditions. Computations were carried out both for the converging (ruled-surface) and smooth curved (advanced-surface) dies. Curvature of the extruded product and simulated deforming grid pattern were also predicted. A sophisticated CAD/CAM package was used in conjunction with the CNC and EDM processes to manufacture the streamlined dies for the off-centric extrusion of square section rods. The theoretical predictions were observed to be in good agreement with the experimental results.

Original languageEnglish (US)
Pages (from-to)321-345
Number of pages25
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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