FEM: Add hard contact with CalculiX (#22513)

src/Mod/Fem/App/FemConstraintContact.cpp

@@ -68,6 +68,11 @@ ConstraintContact::ConstraintContact()
                       "ConstraintContact",
                       App::PropertyType(App::Prop_None),
                       "Thermal contact conductance");
+    ADD_PROPERTY_TYPE(HardContact,
+                      (false),
+                      "ConstraintContact",
+                      App::PropertyType(App::Prop_None),
+                      "Enable hard contact");
 }
 
 App::DocumentObjectExecReturn* ConstraintContact::execute()

src/Mod/Fem/App/FemConstraintContact.h

@@ -53,6 +53,7 @@ public:
     App::PropertyStiffnessDensity StickSlope;
     App::PropertyBool EnableThermalContact;
     App::PropertyStringList ThermalContactConductance;
+    App::PropertyBool HardContact;
 
     // etc
     /* */

src/Mod/Fem/femsolver/calculix/write_constraint_contact.py

@@ -81,9 +81,12 @@ def write_constraint(f, femobj, contact_obj, ccxwriter):
     dep_surf = "DEP" + contact_obj.Name
     f.write(f"{dep_surf}, {ind_surf}\n")
     f.write(f"*SURFACE INTERACTION, NAME=INT{contact_obj.Name}\n")
-    f.write("*SURFACE BEHAVIOR, PRESSURE-OVERCLOSURE=LINEAR\n")
-    slope = contact_obj.Slope.getValueAs("MPa/mm").Value
-    f.write(f"{slope:.13G}\n")
+    if contact_obj.HardContact:
+        f.write("*SURFACE BEHAVIOR, PRESSURE-OVERCLOSURE=HARD\n")
+    else:
+        f.write("*SURFACE BEHAVIOR, PRESSURE-OVERCLOSURE=LINEAR\n")
+        slope = contact_obj.Slope.getValueAs("MPa/mm").Value
+        f.write(f"{slope:.13G}\n")
     if contact_obj.Friction:
         f.write("*FRICTION\n")
         friction = contact_obj.FrictionCoefficient