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c019071604
applications/test/rigidBodyDynamics/spring: Test of the linear spring with damper restraint
Damped simple harmonic motion of a weight on a spring is simulated and
the results compared with analytical solution
Test-spring
gnuplot spring.gnuplot
evince spring.eps
This development is sponsored by Carnegie Wave Energy Ltd.
153 lines
3.9 KiB
C
153 lines
3.9 KiB
C
/*---------------------------------------------------------------------------*\
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========= |
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\\ / F ield | OpenFOAM: The Open Source CFD Toolbox
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\\ / O peration |
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\\ / A nd | Copyright (C) 2016 OpenFOAM Foundation
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\\/ M anipulation |
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-------------------------------------------------------------------------------
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License
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This file is part of OpenFOAM.
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OpenFOAM is free software: you can redistribute it and/or modify it
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under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
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ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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for more details.
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You should have received a copy of the GNU General Public License
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along with OpenFOAM. If not, see <http://www.gnu.org/licenses/>.
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\*---------------------------------------------------------------------------*/
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#include "linearSpring.H"
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#include "rigidBodyModel.H"
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#include "addToRunTimeSelectionTable.H"
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// * * * * * * * * * * * * * * Static Data Members * * * * * * * * * * * * * //
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namespace Foam
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{
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namespace RBD
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{
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namespace restraints
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{
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defineTypeNameAndDebug(linearSpring, 0);
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addToRunTimeSelectionTable
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(
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restraint,
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linearSpring,
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dictionary
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);
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}
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}
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}
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// * * * * * * * * * * * * * * * * Constructors * * * * * * * * * * * * * * //
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Foam::RBD::restraints::linearSpring::linearSpring
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(
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const word& name,
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const dictionary& dict,
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const rigidBodyModel& model
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)
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:
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restraint(name, dict, model),
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anchor_(),
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refAttachmentPt_(),
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stiffness_(),
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damping_(),
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restLength_()
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{
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read(dict);
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}
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// * * * * * * * * * * * * * * * * Destructor * * * * * * * * * * * * * * * //
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Foam::RBD::restraints::linearSpring::~linearSpring()
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{}
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// * * * * * * * * * * * * * * Member Functions * * * * * * * * * * * * * * //
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Foam::spatialVector Foam::RBD::restraints::linearSpring::restrain() const
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{
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spatialVector attachmentPt
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(
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model_.X0(bodyIndex_).inv() && spatialVector(Zero, refAttachmentPt_)
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);
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// Current axis of the spring
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vector r = attachmentPt.l() - anchor_;
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scalar magR = mag(r);
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r /= (magR + VSMALL);
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// Velocity of the end of the spring
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vector v = model_.v(bodyIndex_, refAttachmentPt_).l();
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// Force and moment including optional damping
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vector force = (-stiffness_*(magR - restLength_) - damping_*(r & v))*r;
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vector moment = (attachmentPt.l() - model_.X0(bodyIndex_).r()) ^ force;
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if (model_.debug)
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{
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Info<< " attachmentPt - anchor " << r*magR
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<< " spring length " << magR
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<< " force " << force
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<< " moment " << moment
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<< endl;
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}
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return spatialVector(moment, force);
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}
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bool Foam::RBD::restraints::linearSpring::read
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(
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const dictionary& dict
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)
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{
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restraint::read(dict);
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coeffs_.lookup("anchor") >> anchor_;
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coeffs_.lookup("refAttachmentPt") >> refAttachmentPt_;
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coeffs_.lookup("stiffness") >> stiffness_;
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coeffs_.lookup("damping") >> damping_;
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coeffs_.lookup("restLength") >> restLength_;
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return true;
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}
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void Foam::RBD::restraints::linearSpring::write
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(
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Ostream& os
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) const
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{
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restraint::write(os);
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os.writeKeyword("anchor")
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<< anchor_ << token::END_STATEMENT << nl;
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os.writeKeyword("refAttachmentPt")
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<< refAttachmentPt_ << token::END_STATEMENT << nl;
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os.writeKeyword("stiffness")
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<< stiffness_ << token::END_STATEMENT << nl;
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os.writeKeyword("damping")
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<< damping_ << token::END_STATEMENT << nl;
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os.writeKeyword("restLength")
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<< restLength_ << token::END_STATEMENT << nl;
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}
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// ************************************************************************* //
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