cl_Material_BhSplineCurve.hpp

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/*
 * BELFEM -- The Berkeley Lab Finite Element Framework
 * Copyright (c) 2026, The Regents of the University of California, through
 * Lawrence Berkeley National Laboratory (subject to receipt of any required
 * approvals from the U.S. Dept. of Energy).  All rights reserved.
 *
 * Developers: Christian Messe, Gregory Giard
 * 
 * See the top-level LICENSE file for the complete license and disclaimer.
 */
 
#ifndef BELFEM_CL_MATERIAL_BHSPLINECURVE_HPP
#define BELFEM_CL_MATERIAL_BHSPLINECURVE_HPP
 
#include "cl_BhCurve.hpp"
#include "cl_Spline.hpp"
namespace belfem
{
    namespace material
    {
        class BhSplineCurve : public BhCurve
        {
            Spline * mNuSpline = nullptr ;  
            Spline * mMuSpline = nullptr ;  
 
            real mBsat = BELFEM_QUIET_NAN ;  
            real mHsat = BELFEM_QUIET_NAN ;  
            real mMsat = BELFEM_QUIET_NAN ;  
 
//------------------------------------------------------------------------------
        public:
//------------------------------------------------------------------------------
 
            BhSplineCurve(const string & aPath, const string & aLabel);
 
//------------------------------------------------------------------------------
 
            ~BhSplineCurve() override ;
 
//------------------------------------------------------------------------------
            real
            nu( const real B ) const override ;
//------------------------------------------------------------------------------

            real
            mu( const real H ) const override ;
 
//------------------------------------------------------------------------------

            void
            dmudH( const real H, real & mu, real & dmudH ) const override ;
 
//------------------------------------------------------------------------------
        private:
//------------------------------------------------------------------------------
 
            void
            load_data( const string & aPath, const string & aLabel );
 
//------------------------------------------------------------------------------
        };
 
//------------------------------------------------------------------------------
 
        inline real
        BhSplineCurve::nu( const real B ) const
        {
            if ( B < mBsat )
            {
                return mNuSpline->eval( B ) * constant::nu0 ;
            }
            else
            {
                return ( B * constant::nu0 - mMsat ) / B ;
            }
        }
 
//------------------------------------------------------------------------------
 
        inline real
        BhSplineCurve::mu( const real H ) const
        {
            if ( H < mHsat )
            {
                return constant::mu0  / mMuSpline->eval( H )  ;
            }
            else
            {
                return ( mMsat + H ) / H * constant::mu0 ;
            }
        }
 
//------------------------------------------------------------------------------
 
        inline void
        BhSplineCurve::dmudH( const real H, real & mu, real & dmudH ) const
        {
            if ( H < mHsat )
            {
                index_t k = mMuSpline->find_col( H );
                real f = mMuSpline->eval( H, k );
                real df = mMuSpline->deval( H, k );
 
                mu = constant::mu0 / f ;
                dmudH = - mu * df / f;
            }
            else
            {
                mu    = ( mMsat + H ) / H * constant::mu0 ;
                dmudH =  -mMsat * constant::mu0 / ( H * H );
            }
        }
 
//------------------------------------------------------------------------------
    }
}
#endif //BELFEM_CL_MATERIAL_BHSPLINECURVE_HPP