Mechanical APDL Structural Analysis Guide

8.4.1.2.6. Gent Hyperelastic Option (TB,HYPER,,,,GENT )

The Gent option (TB,HYPER,,,,GENT) has an applicable strain level of up to 300%.

An example input listing showing a typical use of the Gent option is presented below.

TB,HYPER,1,,,GENT !Activate Gent data table

TBDATA,1,3.0 !Define initial shear modulus

TBDATA,2,42.0 !Define limiting I 1 - 3

TBDATA,3,0.001 !Define incompressibility parameter

!(as 2/K, K is the bulk modulus)

Refer to Gent Hyperelastic Material Constants for a description of the material constants required for
this option.

8.4.1.2.7. Yeoh Hyperelastic Option (TB,HYPER,,,,YEOH)

The Yeoh option (TB,HYPER,,,,YEOH) is a reduced polynomial form of the hyperelasticity option TB,HY-
PER,,,,POLY. An example of a 2 term Yeoh model is TB,HYPER,1,,2,YEOH.

Similar to the polynomial form option, the higher order terms may provide a better approximation to
a solution at higher strain.

For NPTS = 1, the Yeoh form option is equivalent to the Neo-Hookean option (see Neo-Hookean Hyper-
elastic Option (TB,HYPER,,,,NEO) (p. 204) for an example input listing).

The following example input listing shows a typical use of the Yeoh option with 2 terms and 1 incom-
pressibility term:

TB,HYPER,1,,2,YEOH !Activate 2 term Yeoh data table

TBDATA,1,0.163498 !Define C 1

TBDATA,2,0.125076 !Define C 2

TBDATA,3,6.93063E-5 !Define first incompressibility parameter

Refer to Yeoh Hyperelastic Material Constants for a description of the material constants required for
this option.

8.4.1.2.8. Blatz-Ko Foam Hyperelastic Option (TB,HYPER,,,,BLATZ)

The Blatz-Ko option (TB,HYPER,,,,BLATZ) is the simplest option for simulating the compressible foam
type of elastomer. This option is analogous to the Neo-Hookean option of incompressible hyperelastic
materials.

An example input listing showing a typical use of the Blatz-Ko option is presented below.

TB,HYPER,1,,,BLATZ !Activate Blatz-Ko data table

TBDATA,1,5.0 !Define initial shear modulus

Refer to Blatz-Ko Foam Hyperelastic Material Constants for a description of the material constants required
for this option.

8.4.1.2.9. Ogden Compressible Foam Hyperelastic Option (TB,HYPER,,,,FOAM)

The Ogden compressible foam option (TB,HYPER,,,,FOAM) simulates highly compressible foam material.
An example of a 3 parameter model is TB,HYPER,1,,3,FOAM. Compared to the Blatz-Ko option, the Ogden
foam option usually provides the best approximation to a solution at larger strain levels. The higher
the number of parameters, the better the fit to the experimental data. It may however cause numerical
difficulties in fitting the material constants, and it requires sufficient data to cover the whole range of

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Modeling Material Nonlinearities