A procedure for determining the constitutive equations for materials exhibiting both time-dependent and time-independent plasticity

Abstract A procedure is given in order to determine various functions and constants entering in a constitutive equation exhibiting both time-dependent and time-independent plasticity, starting from a set of experimental data. As typical experiments one has chosen the symmetric longitudinal impact of two identical bars, since for such kinds of problems a great deal of experimental data are available. The unloading process is also considered since it is mainly during unloading that interesting aspects concerning “plasticity” may be put into evidence. A “relaxation boundary” which plays a main role in time-dependent plasticity is introduced. Several computed examples are given in order to show the influence of various functions or constants entering in the constitutive equation.