Abstract: The deformation law of combined extrusion was studied by the photoplastic method with polycarbanate as a simulative material in the paper. The curves of strain distribution in the whole deformation zone were obtained. The characteristic of strain distribution showed that there were three special deformation zones, rigid zone, extrusion zone and upsetting zone, in the specimen. By way of the isochroinetic stripe patterns and the results of strain analyses, it was proved that there was a neutral region in the process of combined extrusion. Based on the location of neutral region in the isochroinetic stripe pattern, the precision of three formulas for calculating the radius of neutral point were compared.

Key words: Combined extrusion, Polycarbanate, Simulation