Add FEM Constraint Tutorial/de

In diesem Tutorium werden wir die Fließgeschwindigkeitsbeschränkung zu FreeCAD hinzufügen und Unterstützung für den Elmer Löser implementieren. Bitte stelle sicher, dass du FEM Modul erweitern gelesen und verstanden hast, bevor du dieses Tutorial liest.

Dieses Tutorium umfasst nur die Implementierung von Beschränkungen in Python. Im Gegensatz zu Löser und Gleichungsbeschränkungen folge der klassischen FEM Modulstruktur. Das heißt, alle Module einer Beschränkung haben dort entweder im oder  Paket Platz.

Zusammenfassung

 * 1) Erstelle Dokumentobjekt: Das Dokumentobjekt, das sich innerhalb der Analyse befindet und durch das die Beschränkung parametrisiert und an Grenzen angehängt werden kann.
 * 2) Erstelle GUI Befehl: Füge dem FEM Arbeitsbereich einen Befehl hinzu, der der aktiven Analyse eine Durchflussbeschränkung hinzufügt.
 * 3) Erstelle ein Aufgabenpaneel: Das Aufgabenpaneel ist erforderlich, um dem Anwender die Möglichkeit zu gewähren, die Grenzen festzulegen, an denen er die Geschwindigkeitsbeschränkung festlegen möchte. Es macht auch die Eingabe der Parameter etwas benutzerfreundlicher.
 * 4) Erweitere Elmers Schreiber: Füge Unterstützung für die neue Beschränkung Elmer hinzu, durch erweitern seines sif Datei Exportierers.

Dokumentobjekt erstellen
In diesem Schritt werden wir die folgenden Dateien modifizieren: und füge die folgenden Dateien hinzu:
 * src/Mod/Fem/CMakeLists.txt
 * src/Mod/Fem/App/CMakeLists.txt
 * src/Mod/Fem/ObjectsFem.py
 * src/Mod/Fem/femobjects/constraint_flowvelocity.py
 * src/Mod/Fem/femviewprovider/view_constraint_flowvelocity.py

Für die neue Beschränkung sind ein Dokumentproxy und ein Ansichtproxy erforderlich. Diese liegen in separaten Modulen vor. Der Dokumentproxy in femobjects und der Ansichtproxy in femviewprovider. Kopiere einfach die Module aus einer bestehenden Beschränkung, z.B. Passe die Typvariable und die Eigenschaften an deine Bedürfnisse an. Der Dokumentproxy der Fließbeschränkung sieht wie folgt aus: class Proxy(FemConstraint.Proxy): Type = &quot;Fem::ConstraintFlowVelocity&quot; def __init__(self, obj): super(Proxy, self).__init__(obj) obj.addProperty(           &quot;App::PropertyFloat&quot;, &quot;VelocityX&quot;,            &quot;Parameter&quot;, &quot;Body heat flux&quot;) obj.addProperty(           &quot;App::PropertyBool&quot;, &quot;VelocityXEnabled&quot;,            &quot;Parameter&quot;, &quot;Body heat flux&quot;) obj.addProperty(           &quot;App::PropertyFloat&quot;, &quot;VelocityY&quot;,            &quot;Parameter&quot;, &quot;Body heat flux&quot;) obj.addProperty(           &quot;App::PropertyBool&quot;, &quot;VelocityYEnabled&quot;,            &quot;Parameter&quot;, &quot;Body heat flux&quot;) obj.addProperty(           &quot;App::PropertyFloat&quot;, &quot;VelocityZ&quot;,            &quot;Parameter&quot;, &quot;Body heat flux&quot;) obj.addProperty(           &quot;App::PropertyBool&quot;, &quot;VelocityZEnabled&quot;,            &quot;Parameter&quot;, &quot;Body heat flux&quot;) obj.addProperty(           &quot;App::PropertyBool&quot;, &quot;NormalToBoundary&quot;,            &quot;Parameter&quot;, &quot;Body heat flux&quot;) The module containing the view proxy might look a little more complicated. But for now just adjust the icon path. We are going to come back to this file in later steps of the tutorial. class ViewProxy(FemConstraint.ViewProxy): def getIcon(self): return &quot;:/icons/fem-constraint-flow-velocity.svg&quot; Add the two new modules to the build system like described in Extend FEM Module. Locate the correct list be searching for constraint modules.
 * femobjects/constraint_selfweight.py
 * femviewprovider/view_constraint_selfweight.py

As all objects of the FEM workbench the velocity constraint must be registered in. The following method adds a velocity constraint to the active document. This method will be used by the GUI command to add the constraint. It must be inserted somewhere in. def makeConstraintFlowVelocity(name=&quot;FlowVelocity&quot;): obj = FreeCAD.ActiveDocument.addObject(&quot;Fem::ConstraintPython&quot;, name) import femobjects.constraint_flowvelocity femobjects.constraint_flowvelocity.Proxy(obj) if FreeCAD.GuiUp: import femviewprovider.view_constraint_flowvelocity femviewprovider.view_constraint_flowvelocity.ViewProxy(obj.ViewObject) return obj

GUI Befehl erstellen
In diesem Schritt werden wir die folgenden Dateien modifizieren: und die folgende neue Datei hinzufügen:
 * src/Mod/Fem/CMakeLists.txt
 * src/Mod/Fem/App/CMakeLists.txt
 * src/Mod/Fem/Gui/Workbench.cpp
 * src/Mod/Fem/femobjects/constraint_flowvelocity.py

The command allows the user to actually add the constraint to the active analysis. Just copy a command from an existing constraint. Commands reside in the  package. Adjust the resources attribute and the make method called in Activated to your needs. Also use a different command id in the addCommand call on the bottom of the module. The following class is the command class of the velocity constraint. class Command(FemCommands.FemCommands):

def __init__(self): super(Command, self).__init__ self.resources = { 'Pixmap': 'fem-constraint-flow-velocity', 'MenuText': QtCore.QT_TRANSLATE_NOOP(               &quot;FEM_ConstraintFlowVelocity&quot;,                &quot;Constraint Velocity&quot;), 'ToolTip': QtCore.QT_TRANSLATE_NOOP(               &quot;FEM_ConstraintFlowVelocity&quot;,                &quot;Creates a FEM constraint body heat flux&quot;)} self.is_active = 'with_analysis'

def Activated(self): App.ActiveDocument.openTransaction(           &quot;Create FemConstraintFlowVelocity&quot;) Gui.addModule(&quot;ObjectsFem&quot;) Gui.doCommand(           &quot;FemGui.getActiveAnalysis.Member += &quot;            &quot;[ObjectsFem.makeConstraintFlowVelocity]&quot;)

Gui.addCommand('FEM_AddConstraintFlowVelocity', Command) Add the new command file to the build system as decripted in Extend FEM Module. Locate the correct list be searching for existing command modules.

Put the command into Gui/Workbench.cpp to add it to the toolbar and menu. Search for an existing constraint of the same category as the new one (e.g. Flow) copy-paste it and adjust the command id. This should be done two times. Once for the menu and again for the toolbar.

Erstellen eines Aufgabenpaneels
In this step we are going to modify the following file: In FreeCAD constraint objects benefit greatly from task panels. Task panels can make use of more powerful input widgets which expose the unit of entered values directely to the user. The velocity constraint even requires the use of a task panel since a task panel is the only way of specifieing the face(s) on which the constraint shall be applied.
 * src/Mod/Fem/femviewprovider/view_constraint_flowvelocity.py

The location of the module in which task panels are implemented is not strictely defined. For the velocity constraint we are just going to put the task panel in the same module we put the view proxy. The task panel is quite complicated. It makes use of the FemSolectionWidgets.BoundarySelector. Thats a qt widget which allows the user to select the boundaries on which the constraint shall be applied. In addition to this widget it generates another one by loading a ui file specifically created for the velocity constraint. Via this widget the velocity vector can be specified.

Most of the time is should be sufficient to just copy this class, use a suitable ui file (instead of TaskPanelFemFlowVelocity.ui) and adjust _initParamWidget as well as _applyWidgetChanges. If the new constraint requires bodies as references instead of boundaries just replace the BoundarySelector object with the SolidSelector. class _TaskPanel(object):

def __init__(self, obj): self._obj = obj self._refWidget = FemSelectionWidgets.BoundarySelector # self._refWidget = FemSelectionWidgets.SolidSelector self._refWidget.setReferences(obj.References) self._paramWidget = Gui.PySideUic.loadUi(           App.getHomePath + &quot;Mod/Fem/femviewprovider/TaskPanelFemFlowVelocity.ui&quot;) self._initParamWidget self.form = [self._refWidget, self._paramWidget] analysis = FemMisc.findAnalysisOfMember(obj) self._mesh = FemMisc.getSingleMember(analysis, &quot;Fem::FemMeshObject&quot;) self._part = self._mesh.Part if self._mesh is not None else None self._partVisible = None self._meshVisible = None

def open(self): if self._mesh is not None and self._part is not None: self._meshVisible = self._mesh.ViewObject.isVisible self._partVisible = self._part.ViewObject.isVisible self._mesh.ViewObject.hide self._part.ViewObject.show

def reject(self): self._restoreVisibility return True

def accept(self): if self._obj.References != self._refWidget.references: self._obj.References = self._refWidget.references self._applyWidgetChanges self._obj.Document.recompute self._restoreVisibility return True

def _restoreVisibility(self): if self._mesh is not None and self._part is not None: if self._meshVisible: self._mesh.ViewObject.show else: self._mesh.ViewObject.hide if self._partVisible: self._part.ViewObject.show else: self._part.ViewObject.hide

def _initParamWidget(self): unit = &quot;m/s&quot; self._paramWidget.velocityXTxt.setText(           str(self._obj.VelocityX) + unit) self._paramWidget.velocityYTxt.setText(           str(self._obj.VelocityY) + unit) self._paramWidget.velocityZTxt.setText(           str(self._obj.VelocityZ) + unit) self._paramWidget.velocityXBox.setChecked(           not self._obj.VelocityXEnabled) self._paramWidget.velocityYBox.setChecked(           not self._obj.VelocityYEnabled) self._paramWidget.velocityZBox.setChecked(           not self._obj.VelocityZEnabled) self._paramWidget.normalBox.setChecked(           self._obj.NormalToBoundary)

def _applyWidgetChanges(self): unit = &quot;m/s&quot; self._obj.VelocityXEnabled = \ not self._paramWidget.velocityXBox.isChecked if self._obj.VelocityXEnabled: quantity = Units.Quantity(self._paramWidget.velocityXTxt.text) self._obj.VelocityX = float(quantity.getValueAs(unit)) self._obj.VelocityYEnabled = \ not self._paramWidget.velocityYBox.isChecked if self._obj.VelocityYEnabled: quantity = Units.Quantity(self._paramWidget.velocityYTxt.text) self._obj.VelocityY = float(quantity.getValueAs(unit)) self._obj.VelocityZEnabled = \ not self._paramWidget.velocityZBox.isChecked if self._obj.VelocityZEnabled: quantity = Units.Quantity(self._paramWidget.velocityZTxt.text) self._obj.VelocityZ = float(quantity.getValueAs(unit)) self._obj.NormalToBoundary = self._paramWidget.normalBox.isChecked The view proxy must be extended to support the task panel we just implemented. The following extended view proxy opens the task panel when the user makes a double click on the constraint object in the tree view. class ViewProxy(FemConstraint.ViewProxy):

def getIcon(self): return &quot;:/icons/fem-constraint-flow-velocity.svg&quot;

def setEdit(self, vobj, mode=0): task = _TaskPanel(vobj.Object) Gui.Control.showDialog(task)

def unsetEdit(self, vobj, mode=0): Gui.Control.closeDialog

def doubleClicked(self, vobj): if Gui.Control.activeDialog: Gui.Control.closeDialog Gui.ActiveDocument.setEdit(vobj.Object.Name) return True

Elmers Schreiber erweitern
In diesem Schritt werden wir die folgenden Dateien modifizieren: Das Schreiber Modul enthält Methoden für alle Gleichungstypen. Je nach Art der Beschränkung, Randbedingung, Anfangsbedingung oder Körperkraft muss man unterschiedliche Methoden modifizieren. Für unsere Strömungsgeschwindigkeit müssen wir _handleFlowBndConditions(...) anpassen. def _handleFlowBndConditions(self): for obj in self._getMember(&quot;Fem::ConstraintFlowVelocity&quot;): if obj.References: for name in obj.References[0][1]: if obj.VelocityXEnabled: velocity = getFromUi(obj.VelocityX, &quot;m/s&quot;, &quot;L/T&quot;) self._boundary(name, &quot;Velocity 1&quot;, velocity) if obj.VelocityYEnabled: velocity = getFromUi(obj.VelocityY, &quot;m/s&quot;, &quot;L/T&quot;) self._boundary(name, &quot;Velocity 2&quot;, velocity) if obj.VelocityZEnabled: velocity = getFromUi(obj.VelocityZ, &quot;m/s&quot;, &quot;L/T&quot;) self._boundary(name, &quot;Velocity 3&quot;, velocity) if obj.NormalToBoundary: self._boundary(name, &quot;Normal-Tangential Velocity&quot;, True) self._handled(obj)
 * src/Mod/Fem/femsolver/elmer/writer.py