August 23, 2024 at 2:53 pm
Armin
Ansys Employee

Hi Richard,

I checked the 2024R2 version and I had a similar experience: the Prony Shear Relaxation option under Viscoelastic group of Engineering Data is not supported in Workbench LS-DYNA.
In Engineering Data application, if you open the LSDYNA External Model – MAT group in the Toolbox, the MAT_GENERAL_VISCOEASTIC option is available which supports Prony series; however, the current implementation in Engineering Data is limited and does not allow for accessing the cards associated with Prony series.
So, I suppose the best approach is to use Command Snippets in Workbench LS-DYNA (in Project Outline, right-click on your model under the Geometry branch and select insert, commands) to implement the model. Other possible approaches are editing the input file directly to add the material card or using LS-PrePost. 
You can obtain more information about this material model, MAT_076, and its format using the keyword manual, on page 581:   https://www.dynasupport.com/manuals/ls-dyna-manuals/ls-dyna_manual_volume_ii_r13.pdf