VCoupledElement.h

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// This file is part of the MercuryDPM project (https://www.mercurydpm.org).
// Copyright (c), The MercuryDPM Developers Team. All rights reserved.
// License: BSD 3-Clause License; see the LICENSE file in the root directory.
 
#ifndef COUPLEDELEMENT_H
#define COUPLEDELEMENT_H
namespace Global_Physical_Variables
{
double lenScale = 1;
 
double timeScale = 1;
}
#endif //COUPLEDELEMENT_H
 
#ifndef VCOUPLEDELEMENT_H
#define VCOUPLEDELEMENT_H
 
namespace oomph
{
 
//=================start_wrapper==================================
//================================================================
template<class ELEMENT>
class VolumeCoupledElement : public virtual ELEMENT
{
 
public:
    
    VolumeCoupledElement()
    {};
    
    ~VolumeCoupledElement()
    {};
    
    void fill_in_contribution_to_residuals(Vector<double>& residuals) override
    {
        // Call the generic residuals function with flag set to 0 using a dummy matrix argument
        fill_in_generic_contribution_to_residuals_pvd(residuals, GeneralisedElement::Dummy_matrix, 0);
        
        // Add nodal coupling force to the residuals
        add_internal_coupling_forces_to_residuals(residuals, GeneralisedElement::Dummy_matrix, 0);
    }
    
    void fill_in_contribution_to_jacobian(Vector<double>& residuals, DenseMatrix<double>& jacobian) override
    {
        //Call the generic routine with the flag set to 1
        fill_in_generic_contribution_to_residuals_pvd(residuals, jacobian, 1);
        
        // Add nodal coupling force to the residuals
        add_internal_coupling_forces_to_residuals(residuals, jacobian, 1);
    }
    
    void set_nodal_coupling_residual(Vector<Vector<double> >& cResidual)
    { nodal_coupling_residual = cResidual; }
    
    inline double& get_nodal_coupling_residual(const unsigned& l, const unsigned& i)
    { return nodal_coupling_residual[l][i]; }
    
    void set_nodal_coupling_jacobian(Vector<Vector<double> >& cJacobian)
    { nodal_coupling_jacobian = cJacobian; }
    
    inline double& get_nodal_coupling_jacobian(const unsigned& l, const unsigned& ll)
    { return nodal_coupling_jacobian[l][ll]; }
    
    void setCouplingStiffness(Vector<Vector<double> >& cStiffness)
    { couplingStiffness = cStiffness; }
    
    inline double& getCouplingStiffness(const unsigned& m, const unsigned& l)
    { return couplingStiffness[m][l]; }
    
    void get_momentum_and_energy(double& mass, Vector<double>& lin_mo, Vector<double>& ang_mo, double& pot_en,
                                 double& kin_en)
    {
        const unsigned DIM = this->dim();
        // Initialise mass
        mass = 0;
        // Initialise momentum
        lin_mo.initialise(0);
        ang_mo.initialise(0);
        // Initialise energy
        pot_en = 0;
        kin_en = 0;
        
        //Set the value of n_intpt
        unsigned n_intpt = this->integral_pt()->nweight();
        
        //Set the Vector to hold local coordinates
        Vector<double> s(DIM);
        
        //Find out how many nodes there are
        const unsigned n_node = this->nnode();
        
        //Find out how many positional dofs there are
        const unsigned n_position_type = this->nnodal_position_type();
        
        //Set up memory for the shape functions
        Shape psi(n_node, n_position_type);
        DShape dpsidxi(n_node, n_position_type, DIM);
        
        // Timescale ratio (non-dim density)
        double lambda_sq = this->lambda_sq();
        
        //Loop over the integration points
        for (unsigned ipt = 0; ipt < n_intpt; ipt++)
        {
            //Assign values of s
            for (unsigned i = 0; i < DIM; i++)
            { s[i] = this->integral_pt()->knot(ipt, i); }
            
            //Get the integral weight
            double w = this->integral_pt()->weight(ipt);
            
            //Call the derivatives of the shape functions and get Jacobian
            double J = this->dshape_lagrangian_at_knot(ipt, psi, dpsidxi);
            
            //Get mass and the coupling weight at the integration point
            double coupling_w = 0;
            for (unsigned l = 0; l < n_node; l++)
            {
                double nodal_coupling_w = dynamic_cast<CoupledSolidNode*>(this->node_pt(l))->get_coupling_weight();
                double psi_ = psi(l);
                coupling_w += psi_ * nodal_coupling_w;
            }
            
            //Storage for Lagrangian coordinates and velocity (initialised to zero)
            Vector<double> interpolated_xi(DIM, 0.0);
            Vector<double> veloc(DIM, 0.0);
            
            //Calculate lagrangian coordinates
            for (unsigned l = 0; l < n_node; l++)
            {
                //Loop over positional dofs
                for (unsigned k = 0; k < n_position_type; k++)
                {
                    //Loop over displacement components (deformed position)
                    for (unsigned i = 0; i < DIM; i++)
                    {
                        //Calculate the Lagrangian coordinates
                        interpolated_xi[i] += this->lagrangian_position_gen(l, k, i) * psi(l, k);
                        
                        //Calculate the velocity components (if unsteady solve)
                        if (this->Unsteady)
                        {
                            veloc[i] += this->dnodal_position_gen_dt(l, k, i) * psi(l, k);
                        }
                    }
                }
            }
            
            //Get isotropic growth factor
            double gamma = 1.0;
            this->get_isotropic_growth(ipt, s, interpolated_xi, gamma);
            
            //Premultiply the undeformed volume ratio (from the isotropic
            // growth), the integral weights, the coupling weights, and the Jacobian
            double W = gamma * w * ( 1.0 - coupling_w ) * J;
            
            DenseMatrix<double> sigma(DIM, DIM);
            DenseMatrix<double> strain(DIM, DIM);
            
            //Now calculate the stress tensor from the constitutive law
            this->get_stress(s, sigma);
            
            // Add pre-stress
            for (unsigned i = 0; i < DIM; i++)
            {
                for (unsigned j = 0; j < DIM; j++)
                {
                    sigma(i, j) += this->prestress(i, j, interpolated_xi);
                }
            }
            
            //get the strain
            this->get_strain(s, strain);
            
            // Initialise
            double local_pot_en = 0;
            double veloc_sq = 0;
            
            // Compute integrals
            for (unsigned i = 0; i < DIM; i++)
            {
                for (unsigned j = 0; j < DIM; j++)
                {
                    local_pot_en += sigma(i, j) * strain(i, j);
                }
                veloc_sq += veloc[i] * veloc[i];
            }
            
            // Mass
            mass += lambda_sq * W;
            // Linear momentum and angular momentum
            Vector<double> cross_product(DIM, 0);
            VectorHelpers::cross(interpolated_xi, veloc, cross_product);
            for (unsigned i = 0; i < DIM; i++)
            {
                lin_mo[i] += lambda_sq * veloc[i] * W;
                ang_mo[i] += lambda_sq * cross_product[i] * W;
            }
            // Potential energy
            pot_en += 0.5 * local_pot_en * W;
            // Kinetic energy
            kin_en += lambda_sq * 0.5 * veloc_sq * W;
        }
    }
 
private:
    
    void fill_in_generic_contribution_to_residuals_pvd(Vector<double>& residuals,
                                                       DenseMatrix<double>& jacobian,
                                                       const unsigned& flag) override
    {
        
        // Get problem dimension
        const unsigned DIM = this->dim();
        
        // Simply set up initial condition?
        if (this->Solid_ic_pt != 0)
        {
            this->fill_in_residuals_for_solid_ic(residuals);
            return;
        }
        
        //Find out how many nodes there are
        const unsigned n_node = this->nnode();
        
        //Find out how many positional dofs there are
        const unsigned n_position_type = this->nnodal_position_type();
        
        //Set up memory for the shape functions
        Shape psi(n_node, n_position_type);
        DShape dpsidxi(n_node, n_position_type, DIM);
        
        //Set the value of Nintpt -- the number of integration points
        const unsigned n_intpt = this->integral_pt()->nweight();
        
        //Set the vector to hold the local coordinates in the element
        Vector<double> s(DIM);
        
        // Timescale ratio (non-dim density)
        double lambda_sq = this->lambda_sq();
        
        // Time factor
        double time_factor = 0.0;
        if (lambda_sq > 0)
        {
            time_factor = this->node_pt(0)->position_time_stepper_pt()->weight(2, 0);
        }
        
        //Integer to store the local equation number
        int local_eqn = 0;
        
        //Loop over the integration points
        for (unsigned ipt = 0; ipt < n_intpt; ipt++)
        {
            //Assign the values of s
            for (unsigned i = 0; i < DIM; ++i)
            { s[i] = this->integral_pt()->knot(ipt, i); }
            
            //Get the integral weight
            double w = this->integral_pt()->weight(ipt);
            
            //Call the derivatives of the shape functions (and get Jacobian)
            double J = this->dshape_lagrangian_at_knot(ipt, psi, dpsidxi);
            
            //Get the coupling weight at the integration point
            double coupling_w = 0;
            for (unsigned l = 0; l < n_node; l++)
            {
                double nodal_coupling_w = dynamic_cast<CoupledSolidNode*>(this->node_pt(l))->get_coupling_weight();
                double psi_ = psi(l);
                coupling_w += psi_ * nodal_coupling_w;
            }
            
            //Calculate interpolated values of the derivative of global position
            //wrt lagrangian coordinates
            DenseMatrix<double> interpolated_G(DIM);
            
            // Setup memory for accelerations
            Vector<double> accel(DIM);
            
            //Initialise to zero
            for (unsigned i = 0; i < DIM; i++)
            {
                // Initialise acclerations
                accel[i] = 0.0;
                for (unsigned j = 0; j < DIM; j++)
                {
                    interpolated_G(i, j) = 0.0;
                }
            }
            
            //Storage for Lagrangian coordinates (initialised to zero)
            Vector<double> interpolated_xi(DIM, 0.0);
            
            //Calculate displacements and derivatives and lagrangian coordinates
            for (unsigned l = 0; l < n_node; l++)
            {
                //Loop over positional dofs
                for (unsigned k = 0; k < n_position_type; k++)
                {
                    double psi_ = psi(l, k);
                    //Loop over displacement components (deformed position)
                    for (unsigned i = 0; i < DIM; i++)
                    {
                        //Calculate the Lagrangian coordinates and the accelerations
                        interpolated_xi[i] += this->lagrangian_position_gen(l, k, i) * psi_;
                        
                        // Only compute accelerations if inertia is switched on
                        if (( lambda_sq > 0.0 ) && ( this->Unsteady ))
                        {
                            accel[i] += this->dnodal_position_gen_dt(2, l, k, i) * psi_;
                        }
                        
                        //Loop over derivative directions
                        for (unsigned j = 0; j < DIM; j++)
                        {
                            interpolated_G(j, i) +=
                                this->nodal_position_gen(l, k, i) * dpsidxi(l, k, j);
                        }
                    }
                }
            }
            
            //Get isotropic growth factor
            double gamma = 1.0;
            this->get_isotropic_growth(ipt, s, interpolated_xi, gamma);
            
            
            //Get body force at current time
            Vector<double> b(DIM);
            this->body_force(interpolated_xi, b);
            
            // We use Cartesian coordinates as the reference coordinate
            // system. In this case the undeformed metric tensor is always
            // the identity matrix -- stretched by the isotropic growth
            double diag_entry = pow(gamma, 2.0 / double(DIM));
            DenseMatrix<double> g(DIM);
            for (unsigned i = 0; i < DIM; i++)
            {
                for (unsigned j = 0; j < DIM; j++)
                {
                    if (i == j)
                    { g(i, j) = diag_entry; }
                    else
                    { g(i, j) = 0.0; }
                }
            }
            
            //Premultiply the undeformed volume ratio (from the isotropic
            // growth), the integral weights, the coupling weights, and the Jacobian
            double W = gamma * w * ( 1.0 - coupling_w ) * J;
            
            //Declare and calculate the deformed metric tensor
            DenseMatrix<double> G(DIM);
            
            //Assign values of G
            for (unsigned i = 0; i < DIM; i++)
            {
                //Do upper half of matrix
                for (unsigned j = i; j < DIM; j++)
                {
                    //Initialise G(i,j) to zero
                    G(i, j) = 0.0;
                    //Now calculate the dot product
                    for (unsigned k = 0; k < DIM; k++)
                    {
                        G(i, j) += interpolated_G(i, k) * interpolated_G(j, k);
                    }
                }
                //Matrix is symmetric so just copy lower half
                for (unsigned j = 0; j < i; j++)
                {
                    G(i, j) = G(j, i);
                }
            }
            
            //Now calculate the stress tensor from the constitutive law
            DenseMatrix<double> sigma(DIM);
            ELEMENT::get_stress(g, G, sigma);
            
            // Add pre-stress
            for (unsigned i = 0; i < DIM; i++)
            {
                for (unsigned j = 0; j < DIM; j++)
                {
                    sigma(i, j) += this->prestress(i, j, interpolated_xi);
                }
            }
            
            // Get stress derivative by FD only needed for Jacobian
            //-----------------------------------------------------
            
            // Stress derivative
            RankFourTensor<double> d_stress_dG(DIM, DIM, DIM, DIM, 0.0);
            // Derivative of metric tensor w.r.t. to nodal coords
            RankFiveTensor<double> d_G_dX(n_node, n_position_type, DIM, DIM, DIM, 0.0);
            
            // Get Jacobian too?
            if (flag == 1)
            {
                // Derivative of metric tensor w.r.t. to discrete positional dofs
                // NOTE: Since G is symmetric we only compute the upper triangle
                //          and DO NOT copy the entries across. Subsequent computations
                //          must (and, in fact, do) therefore only operate with upper
                //          triangular entries
                for (unsigned ll = 0; ll < n_node; ll++)
                {
                    for (unsigned kk = 0; kk < n_position_type; kk++)
                    {
                        for (unsigned ii = 0; ii < DIM; ii++)
                        {
                            for (unsigned aa = 0; aa < DIM; aa++)
                            {
                                for (unsigned bb = aa; bb < DIM; bb++)
                                {
                                    d_G_dX(ll, kk, ii, aa, bb) =
                                        interpolated_G(aa, ii) * dpsidxi(ll, kk, bb) +
                                            interpolated_G(bb, ii) * dpsidxi(ll, kk, aa);
                                }
                            }
                        }
                    }
                }
                
                //Get the "upper triangular" entries of the derivatives of the stress
                //tensor with respect to G
                this->get_d_stress_dG_upper(g, G, sigma, d_stress_dG);
            }
            
            //=====EQUATIONS OF ELASTICITY FROM PRINCIPLE OF VIRTUAL DISPLACEMENTS========
            
            //Loop over the test functions, nodes of the element
            for (unsigned l = 0; l < n_node; l++)
            {
                //Loop of types of dofs
                for (unsigned k = 0; k < n_position_type; k++)
                {
                    // Offset for faster access
                    const unsigned offset5 = dpsidxi.offset(l, k);
                    
                    //Loop over the displacement components
                    for (unsigned i = 0; i < DIM; i++)
                    {
                        //Get the equation number
                        local_eqn = this->position_local_eqn(l, k, i);
                        
                        /*IF it's not a boundary condition*/
                        if (local_eqn >= 0)
                        {
                            //Initialise contribution to sum
                            double sum = 0.0;
                            
                            // Acceleration and body force
                            sum += ( lambda_sq * accel[i] - b[i] ) * psi(l, k);
                            
                            // Stress term
                            for (unsigned a = 0; a < DIM; a++)
                            {
                                unsigned count = offset5;
                                for (unsigned b = 0; b < DIM; b++)
                                {
                                    //Add the stress terms to the residuals
                                    sum += sigma(a, b) * interpolated_G(a, i) *
                                        dpsidxi.raw_direct_access(count);
                                    ++count;
                                }
                            }
                            residuals[local_eqn] += W * sum;
                            
                            // Get Jacobian too?
                            if (flag == 1)
                            {
                                // Offset for faster access in general stress loop
                                const unsigned offset1 = d_G_dX.offset(l, k, i);
                                
                                //Loop over the nodes of the element again
                                for (unsigned ll = 0; ll < n_node; ll++)
                                {
                                    //Loop of types of dofs again
                                    for (unsigned kk = 0; kk < n_position_type; kk++)
                                    {
                                        //Loop over the displacement components again
                                        for (unsigned ii = 0; ii < DIM; ii++)
                                        {
                                            //Get the number of the unknown
                                            int local_unknown = this->position_local_eqn(ll, kk, ii);
                                            
                                            /*IF it's not a boundary condition*/
                                            if (local_unknown >= 0)
                                            {
                                                // Offset for faster access in general stress loop
                                                const unsigned offset2 = d_G_dX.offset(ll, kk, ii);
                                                const unsigned offset4 = dpsidxi.offset(ll, kk);
                                                
                                                // General stress term
                                                //--------------------
                                                double sum = 0.0;
                                                unsigned count1 = offset1;
                                                for (unsigned a = 0; a < DIM; a++)
                                                {
                                                    // Bump up direct access because we're only
                                                    // accessing upper triangle
                                                    count1 += a;
                                                    for (unsigned b = a; b < DIM; b++)
                                                    {
                                                        double factor = d_G_dX.raw_direct_access(count1);
                                                        if (a == b) factor *= 0.5;
                                                        
                                                        // Offset for faster access
                                                        unsigned offset3 = d_stress_dG.offset(a, b);
                                                        unsigned count2 = offset2;
                                                        unsigned count3 = offset3;
                                                        
                                                        for (unsigned aa = 0; aa < DIM; aa++)
                                                        {
                                                            // Bump up direct access because we're only
                                                            // accessing upper triangle
                                                            count2 += aa;
                                                            count3 += aa;
                                                            
                                                            // Only upper half of derivatives w.r.t. symm tensor
                                                            for (unsigned bb = aa; bb < DIM; bb++)
                                                            {
                                                                sum += factor *
                                                                    d_stress_dG.raw_direct_access(count3) *
                                                                    d_G_dX.raw_direct_access(count2);
                                                                ++count2;
                                                                ++count3;
                                                            }
                                                        }
                                                        ++count1;
                                                    }
                                                    
                                                }
                                                
                                                // Multiply by weight and add contribution
                                                // (Add directly because this bit is nonsymmetric)
                                                jacobian(local_eqn, local_unknown) += sum * W;
                                                
                                                // Only upper triangle (no separate test for bc as
                                                // local_eqn is already nonnegative)
                                                if (( i == ii ) && ( local_unknown >= local_eqn ))
                                                {
                                                    //Initialise contribution
                                                    double sum = 0.0;
                                                    
                                                    // Inertia term
                                                    sum += lambda_sq * time_factor * psi(ll, kk) * psi(l, k);
                                                    
                                                    // Stress term
                                                    unsigned count4 = offset4;
                                                    for (unsigned a = 0; a < DIM; a++)
                                                    {
                                                        //Cache term
                                                        const double factor =
                                                            dpsidxi.raw_direct_access(count4);// ll ,kk
                                                        ++count4;
                                                        
                                                        unsigned count5 = offset5;
                                                        for (unsigned b = 0; b < DIM; b++)
                                                        {
                                                            sum += sigma(a, b) * factor *
                                                                dpsidxi.raw_direct_access(count5); // l   ,k
                                                            ++count5;
                                                        }
                                                    }
                                                    //Add contribution to jacobian
                                                    jacobian(local_eqn, local_unknown) += sum * W;
                                                    //Add to lower triangular section
                                                    if (local_eqn != local_unknown)
                                                    {
                                                        jacobian(local_unknown, local_eqn) += sum * W;
                                                    }
                                                }
                                                
                                            } //End of if not boundary condition
                                        }
                                    }
                                }
                            }
                            
                        } //End of if not boundary condition
                        
                    } //End of loop over coordinate directions
                } //End of loop over type of dof
            } //End of loop over shape functions
        } //End of loop over integration points
    }
    
    void add_internal_coupling_forces_to_residuals(Vector<double>& residuals,
                                                   DenseMatrix<double>& jacobian,
                                                   const unsigned& flag)
    {
        // No further action if no coupling forces
        if (nodal_coupling_residual.size() == 0) return;
        
        // Find out how many nodes there are
        const unsigned n_node = this->nnode();
        const unsigned DIM = this->dim();
        
        // Find out how many positional dofs there are
        unsigned n_position_type = this->nnodal_position_type();
        
        // Set up memory for the shape/test functions
        Shape psi(n_node);
        
        // Loop over all nodes belonging to the element
        int local_eqn = 0;
        // Loop over the nodes of the element
        for (unsigned l = 0; l < n_node; l++)
        {
            // Loop of types of dofs
            for (unsigned k = 0; k < n_position_type; k++)
            {
                // Loop over the force components
                for (unsigned i = 0; i < DIM; i++)
                {
                    // Get the local equation
                    local_eqn = this->position_local_eqn(l, k, i);
                    // IF it's not a boundary condition and the interpolated force is nonzero
                    if (local_eqn >= 0)
                    {
                        // add the nodal coupling residual to the global residual vector
                        residuals[local_eqn] += nodal_coupling_residual[l][i];
                    }
                    // Get Jacobian too?
                    if (flag == 1)
                    {
                        // No further action if no coupling forces
                        if (nodal_coupling_jacobian.size() == 0) continue;
                        
                        // Loop over the nodes of the element again
                        for (unsigned ll = 0; ll < n_node; ll++)
                        {
                            // Loop of types of dofs again
                            for (unsigned kk = 0; kk < n_position_type; kk++)
                            {
                                // Loop over the force components again
                                for (unsigned ii = 0; ii < DIM; ii++)
                                {
                                    // Get the number of the unknown
                                    int local_unknown = this->position_local_eqn(ll, kk, ii);
                                    // IF it's not a boundary condition
                                    if (( local_unknown >= 0 ) && ( i == ii ) && ( local_unknown >= local_eqn ))
                                    {
                                        // add the nodal coupling jacobian to the global jacobian matrix
                                        jacobian(local_eqn, local_unknown) += nodal_coupling_jacobian[l][ll];
                                        if (local_eqn != local_unknown)
                                        {
                                            jacobian(local_unknown, local_eqn) += nodal_coupling_jacobian[l][ll];
                                        }
                                    }
                                }
                            }
                        }
                    }
                }
            }
        }
    }
    
    void output(std::ostream& outfile, const unsigned& n_plot) override
    {
        const unsigned DIM = this->dim();
        Vector<double> x(DIM);
        Vector<double> dxdt(DIM);
        Vector<double> s(DIM);
        
        // Tecplot header info
        outfile << this->tecplot_zone_string(n_plot);
        
        // Loop over plot points
        unsigned num_plot_points = this->nplot_points(n_plot);
        for (unsigned iplot = 0; iplot < num_plot_points; iplot++)
        {
            // Get local coordinates of plot point
            this->get_s_plot(iplot, n_plot, s);
            
            // Get Eulerian coordinates
            this->interpolated_x(s, x);
            SolidFiniteElement* el_pt = dynamic_cast<SolidFiniteElement*>(this);
            el_pt->interpolated_dxdt(s, 1, dxdt);
            
            // Dummy integration point
            unsigned ipt = 0;
            
            // Output the x,y,..
            for (unsigned i = 0; i < DIM; i++)
            { outfile << x[i] * Global_Physical_Variables::lenScale << " "; }
            
            // Output velocity dnodal_position_gen_dt
            for (unsigned i = 0; i < DIM; i++)
            {
                outfile << dxdt[i] * ( Global_Physical_Variables::lenScale / Global_Physical_Variables::timeScale )
                        << " ";
            }
            
            //Find the number of nodes
            const unsigned n_node = this->nnode();
            //Find the number of positional types
            const unsigned n_position_type = this->nnodal_position_type();
            //Assign storage for the local shape function
            Shape psi(n_node, n_position_type);
            //Find the values of shape function
            this->shape(s, psi);
            // Initialize coupling weight
            double w = 0;
            // Loop over the local nodes
            for (unsigned l = 0; l < n_node; l++)
            {
                double nodal_coupling_w = dynamic_cast<CoupledSolidNode*>(this->node_pt(l))->get_coupling_weight();
                w += nodal_coupling_w * psi(l);
            }
            // Output coupling weight
            outfile << w << " ";
            
            outfile << std::endl;
        }
        
        // Write tecplot footer (e.g. FE connectivity lists)
        this->write_tecplot_zone_footer(outfile, n_plot);
        outfile << std::endl;
    }
    
    Vector<Vector<double> > nodal_coupling_residual;
    
    Vector<Vector<double> > nodal_coupling_jacobian;
    
    Vector<Vector<double> > couplingStiffness;
    
};
 
 
//===========start_face_geometry==============================================
//============================================================================
template<class ELEMENT>
class FaceGeometry<VolumeCoupledElement<ELEMENT> > :
    public virtual FaceGeometry<ELEMENT>
{
public:
    
    FaceGeometry() : FaceGeometry<ELEMENT>()
    {}
    
};
 
}
 
#endif //VCOUPLEDELEMENT_H