Hyperelasticity can be used to analyze rubber-like materials (elastomers) that undergo large strains and displacements, with small volume changes (nearly incompressible materials). Large strain theory is required (in the Mechanical application, set Large Deflection to On).

The hyperelastic material models are isotropic and constant with respect to temperature. The hyperelastic materials are also assumed to be nearly or purely incompressible. Thermal expansion, in the material, is also assumed to be isotropic.

Experimental testing data can be input for a material, and then using the curve fitting module (see Curve Fitting), calculate coefficients for various hyperelastic material models. Another option is to make use of the Response Function which allows the use of experimental testing data and the definition of incompressibility parameters. The allowed experimental testing data are Uniaxial Test Data, Biaxial Test Data, Shear Test Data, Volumetric Test Data, Simple Shear Test Data, Uniaxial Tension Test Data, and Uniaxial Compression Test Data. The definition of the incompressibility parameters is sequential and associated with a given index. To delete values requires that they be deleted from the end of the sequence.

Mullins effect is used for modeling load-induced changes to constitutive response exhibited by some hyperelastic materials. Mullins Effect should be used in conjunction with a hyperelastic material model except for Blatz-Ko and Ogden Foam models.

For additional information on these hyperelastic models see Hyperelasticity in the Material Reference