The Valanis-Landel (VL) hyperelasticity material model was added to Abaqus Standard in R2021x FD04 and then added to Abaqus Explicit in R2022x FD04.  From the R2021x release notes:

The Valanis-Landel model is an isotropic hyperelastic model in which the hyperelastic potential is written as three separable identical functions of the principal stretches (Valanis-Landel form). In Abaqus you define the model by specifying uniaxial test data that must include data from both tension tests and compression tests. Abaqus computes a strain energy potential that reproduces the specified test data exactly. The model is similar to the Marlow model (Marlow form) available in Abaqus. Both models can reproduce the specified data exactly. However, the Valanis-Landel model allows you to specify both tensile and compressive data while the Marlow model allows you to specify either tensile or compressive data (or more generally, specify only one deviatoric test data set).

In R2023x FD01 of the 3DExperience Platform, the Valanis-Landel material model has been added to the material calibration app.  In the calibration app's user interface, the user selects one uniaxial tension test and one uniaxial compression test to define the VL model.   Reminder: in the calibration app, the Marlow model is defined by choosing one uniaxial test (either tension or compression, but not both).

In this demo video we show how one selects the Valanis-Landel hyperelasticity model in the calibration app and make a few comments about the quality of the fit.

In the video below, we use the "calibration case" new feature to show a comparison of the VL model to other hyperelasticity forms.

In this 3rd and last video, we create a 3rd calibration case and show a comparison to the Marlow model.

Update:   In the 2023x FD02 release of Abaqus, the VL model was updated to allow the use of Biaxial Test Data.  The material calibration app was also updated to all this usage:

The attached zip file contains a single 3dxml file that contains the test data used above.

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