A viscoelastic-viscoplastic mechanical model of time-dependent materials based on variable-order fractional derivative

A fractional viscoelastic-viscoplastic model is developed for time-dependent materials, by considering the reference stress in the fractional viscoelastic body. Using this model, the creep, stress relaxation and strain rate behavior is numerically analyzed for frozen soil and zeonex results, with the consideration of continuous order functions that conform to the order interval limits. Subsequently, a variable-order viscoelastic-viscoplastic...