WPK4FEM
commented
10 months ago Dear all,
Yesterday I had a talk with Raymond. He suggested to have an option to use non-objective stresses in DSettlement, as our current users would like to have the same results in the new DSettlement as the previous one.
Although I am totally convienced that by using a non-objective stress in large deformation (large strain) analysis, some thermodynamic laws are violated and the results are incorrect, I added the option to Kratos-Geo in order to produce the old results. We are able to switch it on and off.
Attached is the previous document that I sent to you, showing that the results of Kratos-Geo are based on objective stress. I preformed the same example (last example) by the non-objective stress. You will see the results are exactly the same as the "old" analytical solution ignoring objective stress.
How to use this feature: • Use "UpdatedLagrangianUPwDiffOrderElement2D6N" instead of "SmallStrainUPwDiffOrderElement2D6N" in "*.mdpa" file • Now you can get the old results by setting "USE_HENCKY_STRAIN" to true in MaterialParameters.json file.
Best regards,
Vahid
Updated_mesh_objective_vs_non-objective_Plaxis.docx 1D Formulation soils 2.docx
Related issue: #11643
Validate "updated_mesh" parameter for NEN-Bjerrum soil model and investigate the effect of it on strains. Possibly the term is "move_mesh_flag" in the project parameters.
After getting more information from Raymond van der Meij: The Plaxis jargon updated_mesh refers to geometrical nonlinear implementation of elements. In Kratos GeoMechanics the UpdatedLagrangian elements are available for that. The move_mesh_flag in ProjectParameters.jsonhas something to do with what we need here, According to a communication from Vahid to Jonathan and Carlos it should be used together with USE_HENCKY_STRAIN in MaterialParameters.json. Both should be false or both should be true.