Viscous Material.
The model of behaviour for the viscous materials chooses the liquid of Newton model. It corresponds to a viscous fluid where the speed of deformation is proportional to the applied load.
If during the creep test the piston is subjected to a constant stress, the material will become deformed continuously at constant speed, what allows us to characterise it as a fluid.
In the relaxation test, a constant strain is applied to the piston, the stress leads to infinite at the same time that is applied to the strain, diminishing quickly to zero and remaining stable in that value.
