An upper bound model with continuous velocity field for strain inhomogeneity analysis in radial forging process

A general method for constructing admissible velocity fields without velocity discontinuities is proposed and applied to derive continuous and non-uniform velocity field for radial forging process. Compared with the previous velocity fields which are classified as parallel velocity fields or contain velocity discontinuities, this newly derived velocity field can describe more realistic mechanics of radial forging process. Based on this velocity field, an analytical model is developed by the upper bound approach. This model is verified by comparing the predicted forging load, displacement distribution and plastic strain with both published experimental data and results of the finite element simulation. To investigate the influences of radial reduction rate and axial feed on the strain inhomogeneity along the axial direction, the plastic strain distribution at the center of the workpiece is predicted. It is concluded that the radial reduction rate and the axial feed contribute to the strain magnitude and the degree of strain inhomogeneity respectively. •General method for constructing velocity field without velocity discontinuity is proposed.•Continuous and non-uniform velocity field for radial forging process is proposed.•Influences of radial reduction rate and axial feed on strain inhomogeneity are studied.