rigidBodyDynamics/restraints: Added linearAxialAngularSpring, linear axial angular spring restraint

Included for backward-compatibility with the 6-DoF solver but in the
future will be re-implemented as a joint rather than body restraint and
accumulated in tau (internal forces) rather than fx (external forces).

src/rigidBodyDynamics/restraints/linearAxialAngularSpring/linearAxialAngularSpring.H

@@ -0,0 +1,125 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | Copyright (C) 2016 OpenFOAM Foundation
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+License
+    This file is part of OpenFOAM.
+
+    OpenFOAM is free software: you can redistribute it and/or modify it
+    under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
+    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+    for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.
+
+Class
+    Foam::RBD::restraints::linearAxialAngularSpring
+
+Description
+    Linear axial angular spring restraint.
+
+SourceFiles
+    linearAxialAngularSpring.C
+
+\*---------------------------------------------------------------------------*/
+
+#ifndef linearAxialAngularSpring_H
+#define linearAxialAngularSpring_H
+
+#include "rigidBodyRestraint.H"
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+namespace Foam
+{
+namespace RBD
+{
+namespace restraints
+{
+
+/*---------------------------------------------------------------------------*\
+                   Class linearAxialAngularSpring Declaration
+\*---------------------------------------------------------------------------*/
+
+class linearAxialAngularSpring
+:
+    public restraint
+{
+    // Private data
+
+        //- Reference orientation where there is no moment
+        tensor refQ_;
+
+        //- Global unit axis around which the motion is sprung
+        vector axis_;
+
+        //- Spring stiffness coefficient (Nm/rad)
+        scalar stiffness_;
+
+        //- Damping coefficient (Nms/rad)
+        scalar damping_;
+
+
+public:
+
+    //- Runtime type information
+    TypeName("linearAxialAngularSpring");
+
+
+    // Constructors
+
+        //- Construct from components
+        linearAxialAngularSpring
+        (
+            const word& name,
+            const dictionary& dict,
+            const rigidBodyModel& model
+        );
+
+        //- Construct and return a clone
+        virtual autoPtr<restraint> clone() const
+        {
+            return autoPtr<restraint>
+            (
+                new linearAxialAngularSpring(*this)
+            );
+        }
+
+
+    //- Destructor
+    virtual ~linearAxialAngularSpring();
+
+
+    // Member Functions
+
+        //- Return the external force applied to the body by this restraint
+        virtual spatialVector restrain() const;
+
+        //- Update properties from given dictionary
+        virtual bool read(const dictionary& dict);
+
+        //- Write
+        virtual void write(Ostream&) const;
+};
+
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+} // End namespace RBD
+} // End namespace RBD
+} // End namespace Foam
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+#endif
+
+// ************************************************************************* //