Upper-bound solutions to axisymmetric extrusion problems

Abstract A method for selecting velocity fields which are admissible is presented for the incompressible material. As illustrations, extrusion processes through three basic types of axisymmetric curved dies have been treated: cosine, elliptic and hyperbolic. Upper-bound theorem is used in obtaining mean extrusion pressures and also in choosing the most suitable deformation pattern for extrusion through square dies. Effects of die geometry, friction and material properties are discussed. A partial list is given of other problems which can be examined.

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