Viscoelasticity is the reaction to stress of a material which behaves as if it were composed of an elastic solid and a viscous fluid where the flow is dependent on certain parameters.
The parameters affecting flow are, amongst others, the temperature, the load and the load application gradient.
The most well known models are those of:
• Maxwell, which represents the behaviour of a solid viscoelastic material that has a totally elastic behaviour under a suddenly applied load (e.g. an impact);
• Kelvin-Voigt, which represents the behaviour of a liquid viscoelastic material that has no instant elasticity. Under a sudden deformation the stresses become infinite.