Materials Sensitive to the Type of Process

Abstract

Several effects associated with the sensitivity of materials to various processes have been long known. Among such processes are: tension or compression; torsion in different directions; various stress combinations, etc. (sensitivity to the type of loading); stretching or compression, etc. (sensitivity to the type of deformation); creep or relaxation, processes with different strain rates, etc. (sensitivity to the type of rheological processes). There are many successful propositions as to how to model these types of sensitivity for every particular case. This presentation proposes a new approach to generalize all these events using a unified model. The model is based on introducing an extended space of events, including stress and strain subspaces, and time scale (or the well-known “internal time scale”). Some subspaces with “single-type processes” ought to be identified. In every single-type process, a subspace of one material model is preferable. Of special importance is the transition from one subspace to another. Under various experimentally examined conditions, it is possible to introduce some simplified quadratic surfaces of constant stress and strain states (measured from their intensities at fixed time points). This approach is applied to various characteristic cases. The important issue of solving the system of equations that describes the behavior of a material in case of complex multi-type processes is discussed