Description of issue: ========== In Workbench Mechanical, why do I get a solver error stating: “An error occurred inside the SOLVER module: The “Reference Units” defined for a material property (e.g. Anand Viscoplasticity, Creep, Viscoelastic Shift Function) does not match the solver unit system” when I use the Anand Plasticity model? I use the MPa, K, s^-1 units when defining my material in the Engineering Data Resolution: ========== Some material models are defined in such a way that there is no straightforward way to convert material coefficients from one unit system to another. For example, if a material law has a term “C1*stress^C2”, there is no direct way to convert this since one ends up with non-standard units. Consequently, the solution must be performed in the same unit system in which the coefficients of these special materials are defined. You will need to set the Solver Units to use the same unit system that you used to define your material model as described below. In this case, using the MPa, K, s^-1 means that the Solver Units will need to use the “umks” units, as opposed to the “nmm”, which is usually the default. To set the appropriate solver units: 1. Click on “Analysis Settings” 2. Look under Analysis Data Management 3. Set Solver Units to Manual 4. Select the umks units Please see the attachment for a visual representation of these steps. A full list of units used in Workbench can be found in the help documentation using the following path: // Mechanical User’s Guide // Features // Solving Overview // Solving Units