1. Viscoelastic behavior of materials

A viscoelastic material subjected instantaneously to a constant stress σ ₀ , far below the elastic limit, will exhibit an instantaneous elastic deformation ε _él followed by an anelastic deformation ε _anél increasing with the time the stress is applied and tending towards a limit value ε _tot (figure 1 ). Complacency: $J\left(t\right)=\frac{\epsilon \left(t\right)}{{\sigma }_0}$