Photoviscoplastic investigations of slip-line fields and principal-stress trajectories in viscoelastoplastic strip for drawing with back tension

Photoviscoplasticity is applied to the drawing with back tension through rollers and wedge-shaped dies in model tests of plane-strain state. The effects of the back tension on the slip-line fields and on the principal-stress trajectories for the strips are discussed in the light of experimental results obtained from the model tests. Actual strips are considered as viscoelastoplastic media in the actual drawing processes. The model specimens used are softened celluloid as the viscoelastoplastic medium for the strip and Araldite as the glassy elastic medium for the dies. At a suitable experimental temperature, the viscoelastoplastic strip is drawn viscoplastically through the gap between the dies mentioned above. The slip-line fields, the principal-stress trajectories in the strip and the normal pressure on the contact surface are greatly influenced by the effect of the back tension.