A convenient physical interpretation may be illustrated by simulating mechanical or electronic models. In the mechanical simulation, a spring represents an elastic or Hookean solid (modulus), while a piston moving in an infinite cylinder filled with a viscous liquid la dash pot) represents the Newtonian liquid (viscosity). Thus, the deformation of the solid (spring is completely recoverable, while that of the liquid (dash-pot) is irrecoverable and is converted to heat. See Figures 4-7, 4-8, 4.9. In conclusion, the elastic energy is conserved and recovered while the viscous energy is dissipated. Linear combinations of these models (linear viscoelasticity) may represent various viscoelastic states The most common ones are the Maxwell visco