An elastic–visco-plastic analysis of ductile expanding ring

We investigate the fragmentation of an elastic–visco-plastic ring in the one-dimensional framework. The governing equations include the effects of large deformation, geometric softening, hydrostatic pressure and materialʹs viscoplasticity. Linear perturbation analysis exhibits a rate-dependent dominant necking pattern. Numerical solution of the governing equations includes wave propagations, and shows that the fragment size is controlled by the unloading wave propagations in the ultimate fragmentation stage. The results are compared with experimental data on the fragmentation of uranium rings under different strain-rates.