FEM: nonlinear material, set nonlinear geometry for nonlinear materia…

…l in ccx solver

src/Mod/Fem/FemTools.py

@@ -340,8 +340,12 @@ def check_prerequisites(self):
                     message += "Frequency analysis: Solver has no EigenmodeLowLimit.\n"
                 elif not hasattr(self.solver, "EigenmodesCount"):
                     message += "Frequency analysis: Solver has no EigenmodesCount.\n"
-            if hasattr(self.solver, "MaterialNonlinearity") and self.solver.MaterialNonlinearity == "nonlinear" and not self.materials_nonlinear:
-                message += "Solver is set to nonlinear materials, but there is no nonlinear material in the analysis. \n"
+            if hasattr(self.solver, "MaterialNonlinearity") and self.solver.MaterialNonlinearity == "nonlinear":
+                if not self.materials_nonlinear:
+                    message += "Solver is set to nonlinear materials, but there is no nonlinear material in the analysis.\n"
+                if self.solver.SolverType == 'FemSolverCalculix' and self.solver.GeometricalNonlinearity != "nonlinear":
+                    # nonlinear geometry --> should be set https://forum.freecadweb.org/viewtopic.php?f=18&t=23101&p=180489#p180489
+                    message += "Solver CalculiX triggers nonlinear geometry for nonlinear material, thus it should to be set too.\n"
         # mesh
         if not self.mesh:
             message += "No mesh object defined in the analysis\n"
@@ -400,7 +404,7 @@ def check_prerequisites(self):
                     if has_nonlinear_material is False:
                         has_nonlinear_material = True
                     else:
-                        message += "At least two nonlinear materials use the same linear base material. Only one nonlinear material for each linear material allowed. \n"
+                        message += "At least two nonlinear materials use the same linear base material. Only one nonlinear material for each linear material allowed.\n"
         # constraints
         if self.analysis_type == "static":
             if not (self.fixed_constraints or self.displacement_constraints):

src/Mod/Fem/PyGui/_CommandFemMaterialMechanicalNonlinear.py

@@ -61,17 +61,20 @@ def Activated(self):
                 FreeCAD.ActiveDocument.openTransaction("Create FemMaterialMechanicalNonlinear")
                 FreeCADGui.addModule("ObjectsFem")
                 FreeCADGui.doCommand(command_to_run)
-            # set the material nonlinear property of the solver to nonlinear if only one solver is available and if this solver is a CalculiX solver
+            # set some property of the solver to nonlinear (only if one solver is available and if this solver is a CalculiX solver):
+            # nonlinear material
+            # nonlinear geometry --> its is triggered anyway https://forum.freecadweb.org/viewtopic.php?f=18&t=23101&p=180489#p180489
             solver_object = None
             for m in FemGui.getActiveAnalysis().Member:
                 if m.isDerivedFrom('Fem::FemSolverObjectPython'):
                     if not solver_object:
                         solver_object = m
                     else:
-                        # we do not change the material nonlinear attribut if we have more than one solver
+                        # we do not change attributes if we have more than one solver, since we do not know which one to take
                         solver_object = None
                         break
             if solver_object and solver_object.SolverType == 'FemSolverCalculix':
                 solver_object.MaterialNonlinearity = "nonlinear"
+                solver_object.GeometricalNonlinearity = "nonlinear"
 
 FreeCADGui.addCommand('FEM_MaterialMechanicalNonlinear', _CommandFemMaterialMechanicalNonlinear())

src/Mod/Fem/PyGui/_CommandFemSolverCalculix.py

@@ -53,6 +53,7 @@ def Activated(self):
         FreeCADGui.addModule("ObjectsFem")
         if has_nonlinear_material_obj:
             FreeCADGui.doCommand("solver = ObjectsFem.makeSolverCalculix()")
+            FreeCADGui.doCommand("solver.GeometricalNonlinearity = 'nonlinear'")
             FreeCADGui.doCommand("solver.MaterialNonlinearity = 'nonlinear'")
             FreeCADGui.doCommand("FemGui.getActiveAnalysis().Member = FemGui.getActiveAnalysis().Member + [solver]")
         else: