Burgers Model 

The Burgers Model is a general model of a viscoelastic material, commonly used to describe a classic creep recovery measurement (see Creep).

The model is a combination of spring and dashpots, arranged as combination of separate component in series and in parallel.

So, in the Burgers models Shear Modulus G*G or shear modulus is defined as the ratio of shear stress and shear strain.G1 and η2 are independent in series and model the separate elastic and viscous components of a material.

G2 and η1 are in parallel which mimics the viscoelastic component of a sample where the immediate spring/elastic response is “dampened” (slowed) by the dashpot/viscous component when a load is applied.

With the stress load removed, G2 recovers, but again is dampened by η1, but will recover completely as long as the applied stress is linear, i.e. within the “linear viscoelastic region”.