INNOVATIVE METHOD FOR STRESS STATE ANALYSIS IN THE DEFORMATION ZONE OF FORMED SPECIMEN
By using visioplasticity method the velocity field can be determined experimentally, and then the stresses can he obtained analytically from these experimental measurements. That means, strain rates and strains are calculated directly from the velocity field while the stress distribution is calculated from an analytical solution of the equilibrium equations and the constitutive equation relating the stress and strain for the material. This method can also provide detailed data of the pressure distribution on the die surface, which is important in the design of the die profile. In the paper cold forward extrusion through a conical die is illustrated by extruding copper alloy specimens with inscribed grid lines. Stress state distribution in plastic deformation region was analyzed using the visioplasticity method. From the flow lines of each element, the velocity and the strain rates are obtained. Finally, the stress components are calculated from the equilibrium and plasticity equations.