Abstract: Investigation by photoplastic simulation on the mechanism. Of the void closing in a cylinder polycarbonate model with an artificial void in the center during upset processes was carried out. The way in which the void was closed was described. It was pointed out that enough effective strain and principal shearing strain were necessary for the void closing. The curve of strain distribution was drawn through computing the strains with Euler coordinate system. The results showed that there was a concentration of strain around the void, and that the void influenced partly the distribution of all strains. The influenced zone was 3 - 5 times larger than the original void, and the strain distribution within the zone was inhomogenous.

Key words: Artificial void, Influenced zone, Photoplasticity, Strain distribution