I developed an orthotropic viscoelastic material model using Abaqus UMAT for finite element implementation. Unfortunatelly, I dont have any expiremental results yet and I wont get some in the near future. Therefore I tried to compare the results with the Abaqus solution. Due to the fact that Abaqus doesnt support anisotropic viscoelasticity I tried to combine a hyperelastic orthotropic St. Venant-Kirchhoff model and viscoelastic properties but gives me the mutually exclusive error. I thought that i could define one relaxation time parameter and the prony parameters k & g = 1, so that the nine independet parameters have the same relaxation times. As already mentioned, this doesnt work.
Does somebody have some information about viscoelastic modelling using an anisotropic elastic law?
Otherwise, has somebody got a paper or something else with an appropriate example of orthotropic viscoelastic modelling, which is easy to copy, so I can ensure my results?
Thank you for your answers.