Asymptotic behavior of creep curves in the Rabotnov nonlinear heredity theory under piecewise constant loadings and memory decay conditions

Some minimal prior constraints are imposed on the two material functions used in the Rabotnov nonlinear constitutive relation. The asymptotic dependence of creep curves on the characteristics of these material functions and on the parameters of loading programs is analytically studied in the case of stepped loadings. Some conditions are obtained for the case when these curves tend to the creep curve under instantaneous loading as t→∞. The importance of the limit value of the creep function derivative at infinity is analyzed for the plastic strain accumulation. A number of distinctions and additional possibilities are found compared to the linear integral relation of viscoelasticity.