linearSpringDamper.H

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    Copyright (C) 2019 OpenCFD Ltd.
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License
    This file is part of OpenFOAM.
 
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Class
    Foam::sixDoFRigidBodyMotionRestraints::linearSpringDamper
 
Description
    sixDoFRigidBodyMotionRestraints model.  Linear Spring-Damper system.
 
    Spring-damper system for restraint. Acts as a "soft" rope when the
    distance between anchor and refAttachmentPt exceed the restLength,
    a system of spring-damper is activated to simulate a soft rope
    de-acceleration
 
SourceFiles
    linearSpringDamper.C
 
\*---------------------------------------------------------------------------*/
 
#ifndef linearSpringDamper_H
#define linearSpringDamper_H
 
#include "sixDoFRigidBodyMotionRestraint.H"
#include "point.H"
#include "Function1.H"
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
namespace Foam
{
 
namespace sixDoFRigidBodyMotionRestraints
{
 
/*---------------------------------------------------------------------------*\
                          Class linearSpringDamper Declaration
\*---------------------------------------------------------------------------*/
 
class linearSpringDamper
:
    public sixDoFRigidBodyMotionRestraint
{
    // Private data
 
        //- Anchor point, where the spring is attached to an immovable
        //  object
        mutable autoPtr<Function1<vector>> anchor_;
 
        //- Reference point of attachment to the solid body
        point refAttachmentPt_;
 
        //- Damping factor
        scalar psi_;
 
        //- System frequency  [1/s]
        scalar wn_;
 
        //- Number of chains in the same system
        scalar numberOfChains_;
 
        //- Rest length - length of spring when no forces are applied to it
        scalar restLength_;
 
        //- Cache old restrain force
        mutable vector oldRestraintForce_;
 
        //- Relaxation factor
        scalar frelax_;
 
 
        /*
        //- Error between ideal length and actual length
        mutable scalar error_;
 
         //- Old error between ideal length and actual length
        mutable scalar oldError_;
 
        //- Integral length error in time
        mutable scalar errorIntegral_;
 
        //- Old integral length error in time
        mutable scalar oldErrorIntegral_;
 
        //- Proportional constant
        scalar P_;
 
        //- Integral constant
        scalar I_;
 
        //- Differential constant
        scalar D_;
 
        //- Initial force
        vector f0_;
 
        mutable scalar wn_;
        */
 
 
public:
 
    //- Runtime type information
    TypeName("linearSpringDamper");
 
 
    // Constructors
 
        //- Construct from components
        linearSpringDamper
        (
            const word& name,
            const dictionary& sDoFRBMRDict
        );
 
        //- Construct and return a clone
        virtual autoPtr<sixDoFRigidBodyMotionRestraint> clone() const
        {
            return autoPtr<sixDoFRigidBodyMotionRestraint>
            (
                new linearSpringDamper(*this)
            );
        }
 
 
    //- Destructor
    virtual ~linearSpringDamper();
 
 
    // Member Functions
 
        //- Calculate the restraint position, force and moment.
        //  Global reference frame vectors.
        virtual void restrain
        (
            const sixDoFRigidBodyMotion& motion,
            vector& restraintPosition,
            vector& restraintForce,
            vector& restraintMoment
        ) const;
 
        //- Update properties from given dictionary
        virtual bool read(const dictionary& sDoFRBMRCoeff);
 
        //- Write
        virtual void write(Ostream&) const;
};
 
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
} // End namespace solidBodyMotionFunctions
} // End namespace Foam
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
#endif
 
// ************************************************************************* //