As the slide above says, the Hencky hyperelastic model was added in 2024x FD01 and 2025x FD01 to A/Std and A/Exp. The motivation was NOT to have yet another material model for elastomers, it was to have a finite strain version of classical Hooke's law.
In R2026x FD01 we have added the Hencky hyperelastic model to the Material Calibration App. The video below demonstrates a calibration using the Hencky hyperelastic material model and also demonstrates the export of unit-cube models (another new feature).
Calibration of hyperelastic Hencky potential-based behaviors in the analytical kernel
Calibration of behaviors using the Hencky potential should work similar to the other hyperelastic potentials in the analytical kernel but with the following particularities.
Because for Hencky we calibrate E and Nu, the deviatoric and volumetric responses are coupled. For the existing potentials (other than Hencky), the kernel performs two sequential calibrations, namely:
(i) Calibration of deviatoric constants using uniaxial, biaxial, planar and/or simple shear test data sets;
(ii) Calibration of the volumetric constants using volumetric test data sets;
However, for the Hencky potential, the kernel will perform only the first calibration and it will use any of the provided test data sets including volumetric. The second calibration (normally used for volumetric constants) will be skipped.
The following calibrations should be possible:
| Supported Behavior | Remarks/Limitations |
| Hencky only | Kernel matches /Standard for both compressible and incompressible Poisson’s ratio values |
| Hencky + Mullins effect | Kernel matches /Standard for both compressible and incompressible Poisson’s ratio values |
| Hencky + Prony | Kernel matches /Standard only for close to incompressible Poisson’s ratio values |
| Hencky + Prony + TRS | Kernel matches /Standard only for close to incompressible Poisson’s ratio values |
| Hencky + Mullins + Prony | Kernel matches /Standard only for close to incompressible Poisson’s ratio values |
| Hencky + Mullins + Prony + TRS | Kernel matches /Standard only for close to incompressible Poisson’s ratio values |
Therefore, for cases involving a viscoelastic response, the user should re-calibrate in numerical mode, if Nu < 0.49.
The zip file below contains a 3dxml file with the elastomer test data and the exported unit cube Abaqus models.
