From 8b9240293076bcb13b1f329f28afa6b2951ea66c Mon Sep 17 00:00:00 2001
From: Henry Weller <http://cfd.direct>
Date: Mon, 11 Apr 2016 15:14:18 +0100
Subject: [PATCH] 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/Make/files | 1 +
.../linearAxialAngularSpring.C | 199 ++++++++++++++++++
.../linearAxialAngularSpring.H | 125 +++++++++++
3 files changed, 325 insertions(+)
create mode 100644 src/rigidBodyDynamics/restraints/linearAxialAngularSpring/linearAxialAngularSpring.C
create mode 100644 src/rigidBodyDynamics/restraints/linearAxialAngularSpring/linearAxialAngularSpring.H
diff --git a/src/rigidBodyDynamics/Make/files b/src/rigidBodyDynamics/Make/files
index bdd244ae8a..b07f5e8c81 100644
--- a/src/rigidBodyDynamics/Make/files
+++ b/src/rigidBodyDynamics/Make/files
@@ -29,6 +29,7 @@ restraints/restraint/rigidBodyRestraint.C
restraints/restraint/rigidBodyRestraintNew.C
restraints/linearSpring/linearSpring.C
restraints/linearDamper/linearDamper.C
+restraints/linearAxialAngularSpring/linearAxialAngularSpring.C
rigidBodyModel/rigidBodyModel.C
rigidBodyModel/forwardDynamics.C
diff --git a/src/rigidBodyDynamics/restraints/linearAxialAngularSpring/linearAxialAngularSpring.C b/src/rigidBodyDynamics/restraints/linearAxialAngularSpring/linearAxialAngularSpring.C
new file mode 100644
index 0000000000..795c9021b7
--- /dev/null
+++ b/src/rigidBodyDynamics/restraints/linearAxialAngularSpring/linearAxialAngularSpring.C
@@ -0,0 +1,199 @@
+/*---------------------------------------------------------------------------*\
+ ========= |
+ \\ / 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/>.
+
+\*---------------------------------------------------------------------------*/
+
+#include "linearAxialAngularSpring.H"
+#include "rigidBodyModel.H"
+#include "addToRunTimeSelectionTable.H"
+
+// * * * * * * * * * * * * * * Static Data Members * * * * * * * * * * * * * //
+
+namespace Foam
+{
+namespace RBD
+{
+namespace restraints
+{
+ defineTypeNameAndDebug(linearAxialAngularSpring, 0);
+
+ addToRunTimeSelectionTable
+ (
+ restraint,
+ linearAxialAngularSpring,
+ dictionary
+ );
+}
+}
+}
+
+
+// * * * * * * * * * * * * * * * * Constructors * * * * * * * * * * * * * * //
+
+Foam::RBD::restraints::linearAxialAngularSpring::
+linearAxialAngularSpring
+(
+ const word& name,
+ const dictionary& dict,
+ const rigidBodyModel& model
+)
+:
+ restraint(name, dict, model)
+{
+ read(dict);
+}
+
+
+// * * * * * * * * * * * * * * * * Destructor * * * * * * * * * * * * * * * //
+
+Foam::RBD::restraints::linearAxialAngularSpring::
+~linearAxialAngularSpring()
+{}
+
+
+// * * * * * * * * * * * * * * Member Functions * * * * * * * * * * * * * * //
+
+Foam::spatialVector
+Foam::RBD::restraints::linearAxialAngularSpring::restrain() const
+{
+ vector refDir = rotationTensor(vector(1, 0, 0), axis_) & vector(0, 1, 0);
+
+ vector oldDir = refQ_ & refDir;
+ vector newDir = model_.X0(bodyID_).E() & refDir;
+
+ if (mag(oldDir & axis_) > 0.95 || mag(newDir & axis_) > 0.95)
+ {
+ // Directions close to the axis, changing reference
+ refDir = rotationTensor(vector(1, 0, 0), axis_) & vector(0, 0, 1);
+ oldDir = refQ_ & refDir;
+ newDir = model_.X0(bodyID_).E() & refDir;
+ }
+
+ // Removing axis component from oldDir and newDir and normalising
+ oldDir -= (axis_ & oldDir)*axis_;
+ oldDir /= (mag(oldDir) + VSMALL);
+
+ newDir -= (axis_ & newDir)*axis_;
+ newDir /= (mag(newDir) + VSMALL);
+
+ scalar theta = mag(acos(min(oldDir & newDir, 1.0)));
+
+ // Temporary axis with sign information
+ vector a = (oldDir ^ newDir);
+
+ // Ensure a is in direction of axis
+ a = (a & axis_)*axis_;
+
+ scalar magA = mag(a);
+
+ if (magA > VSMALL)
+ {
+ a /= magA;
+ }
+ else
+ {
+ a = Zero;
+ }
+
+ // Damping of along axis angular velocity only
+ vector moment
+ (
+ -(
+ stiffness_*theta
+ + damping_*(model_.v(model_.master(bodyID_)).w() & a)
+ )*a
+ );
+
+ if (model_.debug)
+ {
+ Info<< " angle " << theta*sign(a & axis_)
+ << " moment " << moment
+ << endl;
+ }
+
+ return spatialVector(moment, Zero);
+}
+
+
+bool Foam::RBD::restraints::linearAxialAngularSpring::read
+(
+ const dictionary& dict
+)
+{
+ restraint::read(dict);
+
+ refQ_ = coeffs_.lookupOrDefault<tensor>("referenceOrientation", I);
+
+ if (mag(mag(refQ_) - sqrt(3.0)) > 1e-9)
+ {
+ FatalErrorInFunction
+ << "referenceOrientation " << refQ_ << " is not a rotation tensor. "
+ << "mag(referenceOrientation) - sqrt(3) = "
+ << mag(refQ_) - sqrt(3.0) << nl
+ << exit(FatalError);
+ }
+
+ axis_ = coeffs_.lookup("axis");
+
+ scalar magAxis(mag(axis_));
+
+ if (magAxis > VSMALL)
+ {
+ axis_ /= magAxis;
+ }
+ else
+ {
+ FatalErrorInFunction
+ << "axis has zero length"
+ << abort(FatalError);
+ }
+
+ coeffs_.lookup("stiffness") >> stiffness_;
+ coeffs_.lookup("damping") >> damping_;
+
+ return true;
+}
+
+
+void Foam::RBD::restraints::linearAxialAngularSpring::write
+(
+ Ostream& os
+) const
+{
+ restraint::write(os);
+
+ os.writeKeyword("referenceOrientation")
+ << refQ_ << token::END_STATEMENT << nl;
+
+ os.writeKeyword("axis")
+ << axis_ << token::END_STATEMENT << nl;
+
+ os.writeKeyword("stiffness")
+ << stiffness_ << token::END_STATEMENT << nl;
+
+ os.writeKeyword("damping")
+ << damping_ << token::END_STATEMENT << nl;
+}
+
+
+// ************************************************************************* //
diff --git a/src/rigidBodyDynamics/restraints/linearAxialAngularSpring/linearAxialAngularSpring.H b/src/rigidBodyDynamics/restraints/linearAxialAngularSpring/linearAxialAngularSpring.H
new file mode 100644
index 0000000000..412e21976a
--- /dev/null
+++ b/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
+
+// ************************************************************************* //
--
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