FEM: Add thermal contact with CalculiX (#22121)

src/Mod/Fem/App/FemConstraintContact.cpp

@@ -58,6 +58,16 @@ ConstraintContact::ConstraintContact()
                       "ConstraintContact",
                       App::PropertyType(App::Prop_None),
                       "Stick slope");
+    ADD_PROPERTY_TYPE(EnableThermalContact,
+                      (false),
+                      "ConstraintContact",
+                      App::PropertyType(App::Prop_None),
+                      "Enable thermal contact");
+    ADD_PROPERTY_TYPE(ThermalContactConductance,
+                      (std::vector<std::string> {}),
+                      "ConstraintContact",
+                      App::PropertyType(App::Prop_None),
+                      "Thermal contact conductance");
 }
 
 App::DocumentObjectExecReturn* ConstraintContact::execute()

src/Mod/Fem/App/FemConstraintContact.h

@@ -51,6 +51,8 @@ public:
     App::PropertyBool Friction;
     App::PropertyFloat FrictionCoefficient;
     App::PropertyStiffnessDensity StickSlope;
+    App::PropertyBool EnableThermalContact;
+    App::PropertyStringList ThermalContactConductance;
 
     // etc
     /* */

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

@@ -89,3 +89,8 @@ def write_constraint(f, femobj, contact_obj, ccxwriter):
         friction = contact_obj.FrictionCoefficient
         stick = contact_obj.StickSlope.getValueAs("MPa/mm").Value
         f.write(f"{friction:.13G}, {stick:.13G}\n")
+    if contact_obj.EnableThermalContact:
+        f.write("*GAP CONDUCTANCE\n")
+        for value in contact_obj.ThermalContactConductance:
+            f.write(f"{value}\n")
+        f.write("\n")