rigidBodyInertiaI.H

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    Copyright (C) 2016 OpenFOAM Foundation
    Copyright (C) 2020 OpenCFD Ltd.
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License
    This file is part of OpenFOAM.
 
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    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.
 
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    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
    for more details.
 
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#include "spatialTransform.H"
#include "transform.H"
#include "dictionary.H"
 
// * * * * * * * * * * * * * Static Member Functions * * * * * * * * * * * * //
 
inline Foam::symmTensor Foam::RBD::rigidBodyInertia::Ioc
(
    const scalar m,
    const vector& c
)
{
    return m*(Foam::I*magSqr(c) - sqr(c));
}
 
 
// * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
 
inline Foam::RBD::rigidBodyInertia::rigidBodyInertia()
:
    m_(Zero),
    c_(Zero),
    Ic_(Zero)
{}
 
 
inline Foam::RBD::rigidBodyInertia::rigidBodyInertia
(
    const scalar m,
    const vector& c,
    const symmTensor& Ic
)
:
    m_(m),
    c_(c),
    Ic_(Ic)
{}
 
 
inline Foam::RBD::rigidBodyInertia::rigidBodyInertia(const dictionary& dict)
:
    m_(dict.get<scalar>("mass")),
    c_(dict.get<vector>("centreOfMass")),
    Ic_(dict.get<symmTensor>("inertia"))
{}
 
 
inline Foam::RBD::rigidBodyInertia::rigidBodyInertia(const spatialTensor& st)
:
    m_(st(3, 3)),
    c_(vector(-st(1, 5), st(0, 5), -st(0, 4))/m_),
    Ic_(symm(st.block<tensor, 0, 0>()()) - Ioc())
{}
 
 
inline Foam::RBD::rigidBodyInertia::rigidBodyInertia(Istream& is)
:
    m_(readScalar(is)),
    c_(is),
    Ic_(is)
{}
 
 
// * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
 
inline Foam::scalar Foam::RBD::rigidBodyInertia::m() const
{
    return m_;
}
 
inline const Foam::vector& Foam::RBD::rigidBodyInertia::c() const
{
    return c_;
}
 
inline const Foam::symmTensor& Foam::RBD::rigidBodyInertia::Ic() const
{
    return Ic_;
}
 
inline Foam::symmTensor Foam::RBD::rigidBodyInertia::Ioc() const
{
    return Ioc(m_, c_);
}
 
inline Foam::symmTensor Foam::RBD::rigidBodyInertia::Icc(const vector& c) const
{
    return Ioc(m_, c - c_);
}
 
inline Foam::symmTensor Foam::RBD::rigidBodyInertia::Io() const
{
    return Ic_ + Ioc();
}
 
 
// * * * * * * * * * * * * * * * Member Operators  * * * * * * * * * * * * * //
 
inline Foam::RBD::rigidBodyInertia::operator spatialTensor() const
{
    tensor mcStar(m_*(*c_));
 
    return spatialTensor
    (
        Io(),   mcStar,
       -mcStar, m_*I
    );
}
 
 
// * * * * * * * * * * * * * * IOstream Operators  * * * * * * * * * * * * * //
 
inline Foam::Istream& Foam::RBD::operator>>
(
    Istream& is,
    rigidBodyInertia& rbi
)
{
    is  >> rbi.m_ >> rbi.c_ >> rbi.Ic_;
    return is;
}
 
 
inline Foam::Ostream& Foam::RBD::operator<<
(
    Ostream& os,
    const rigidBodyInertia& rbi
)
{
    os  << rbi.m_ << nl << rbi.c_ << nl << rbi.Ic_ << endl;
    return os;
}
 
 
// * * * * * * * * * * * * * * * Global Operators  * * * * * * * * * * * * * //
 
namespace Foam
{
namespace RBD
{
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
//- Return the rigid-body inertia of the combined body
inline rigidBodyInertia operator+
(
    const rigidBodyInertia& rbi1,
    const rigidBodyInertia& rbi2
)
{
    const scalar m12 = rbi1.m() + rbi2.m();
    const vector c12 = (rbi1.m()*rbi1.c() + rbi2.m()*rbi2.c())/m12;
 
    return rigidBodyInertia
    (
        m12,
        c12,
        rbi1.Ic() + rbi1.Icc(c12) + rbi2.Ic() + rbi2.Icc(c12)
    );
}
 
 
//- Inner-product with a spatialVector (e.g. velocity returning the momentum)
inline spatialVector operator&
(
    const rigidBodyInertia& rbi,
    const spatialVector& sv
)
{
    const vector av(sv.w());
    const vector lv(sv.l());
 
    return spatialVector
    (
        (rbi.Io() & av) + rbi.m()*(rbi.c() ^ lv),
        rbi.m()*lv - rbi.m()*(rbi.c() ^ av)
    );
}
 
 
//- Return (^BX_A)^* I ^AX_B
inline rigidBodyInertia transform
(
    const spatialTransform& X,
    const rigidBodyInertia& I
)
{
    const vector Xc((X.E().T() & I.c()) + X.r());
 
    return rigidBodyInertia
    (
        I.m(),
        Xc,
        transform(X.E().T(), I.Ic())
    );
}
 
 
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
} // End namespace RBD
} // End namespace Foam
 
 
// * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
 
inline Foam::scalar Foam::RBD::rigidBodyInertia::kineticEnergy
(
    const spatialVector& v
)
{
    return 0.5*(v && (*this & v));
}
 
 
// * * * * * * * * * * * * * * * Member Operators  * * * * * * * * * * * * * //
 
inline void Foam::RBD::rigidBodyInertia::operator+=
(
    const rigidBodyInertia& rbi
)
{
    *this = *this + rbi;
}
 
 
// ************************************************************************* //