Three-, four-, and five-parameter models

To calculate the stress relaxation time for the standard linear solid model with a second spring added parallel to the initial spring, use 

To calculate the stress relaxation time for the Maxwell model alone, use 

To calculate the shear modulus of elasticity G at any given time t, use 

To calculate the shear modulus for the elastic portion (below the elastic limit), use 

Formulas for linear viscoelastic models can be apphed to tensile deformation as well as shear deformation by replacing the shear stress x with tensile stress o, shear strain y with tensile strain e, shear modulus G with Young s tensile modulus E, and newtonian shear viscosity T with Trouton s tensile viscosity iig [11—13]. 

---