Fem3DElementCube.h

// This file is a part of the OpenSurgSim project.
// Copyright 2013, SimQuest Solutions Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#ifndef SURGSIM_PHYSICS_FEM3DELEMENTCUBE_H
#define SURGSIM_PHYSICS_FEM3DELEMENTCUBE_H

#include <array>

#include "SurgSim/Physics/FemElement.h"
#include "SurgSim/Math/GaussLegendreQuadrature.h"

namespace SurgSim
{

namespace Physics
{
SURGSIM_STATIC_REGISTRATION(Fem3DElementCube);

class Fem3DElementCube : public FemElement
{
public:
    Fem3DElementCube();

    explicit Fem3DElementCube(std::array<size_t, 8> nodeIds);

    explicit Fem3DElementCube(std::shared_ptr<FemElementStructs::FemElementParameter> elementData);

    SURGSIM_CLASSNAME(SurgSim::Physics::Fem3DElementCube)

    
    void initialize(const SurgSim::Math::OdeState& state) override;

    double getVolume(const SurgSim::Math::OdeState& state) const override;

    SurgSim::Math::Vector computeCartesianCoordinate(const SurgSim::Math::OdeState& state,
            const SurgSim::Math::Vector& naturalCoordinate) const override;

    SurgSim::Math::Vector computeNaturalCoordinate(const SurgSim::Math::OdeState& state,
            const SurgSim::Math::Vector& cartesianCoordinate) const override;

protected:
    void initializeMembers();

    void buildConstitutiveMaterialMatrix(Eigen::Matrix<double, 6, 6>* constitutiveMatrix);

    void computeStiffness(const SurgSim::Math::OdeState& state,
                          Eigen::Matrix<double, 6, 24>* strain,
                          Eigen::Matrix<double, 6, 24>* stress,
                          SurgSim::Math::Matrix* k);

    void computeMass(const SurgSim::Math::OdeState& state, SurgSim::Math::Matrix* m);

    void doUpdateFMDK(const Math::OdeState& state, int options) override;

    void addStrainStressStiffnessAtPoint(const SurgSim::Math::OdeState& state,
                                         const SurgSim::Math::gaussQuadraturePoint& epsilon,
                                         const SurgSim::Math::gaussQuadraturePoint& eta,
                                         const SurgSim::Math::gaussQuadraturePoint& mu,
                                         Eigen::Matrix<double, 6, 24>* strain,
                                         Eigen::Matrix<double, 6, 24>* stress,
                                         SurgSim::Math::Matrix* k);

    void addMassMatrixAtPoint(const SurgSim::Math::OdeState& state,
                              const SurgSim::Math::gaussQuadraturePoint& epsilon,
                              const SurgSim::Math::gaussQuadraturePoint& eta,
                              const SurgSim::Math::gaussQuadraturePoint& mu,
                              SurgSim::Math::Matrix* m);

    void evaluateJ(const SurgSim::Math::OdeState& state, double epsilon, double eta, double mu,
                   SurgSim::Math::Matrix33d* J,
                   SurgSim::Math::Matrix33d* Jinv,
                   double* detJ) const;

    void evaluateStrainDisplacement(double epsilon, double eta, double mu, const SurgSim::Math::Matrix33d& Jinv,
                                    Eigen::Matrix<double, 6, 24>* B) const;

    double m_restVolume;

    std::array<double, 8> m_shapeFunctionsEpsilonSign;
    std::array<double, 8> m_shapeFunctionsEtaSign;
    std::array<double, 8> m_shapeFunctionsMuSign;


    double shapeFunction(size_t i, double epsilon, double eta, double mu) const;

    double dShapeFunctiondepsilon(size_t i, double epsilon, double eta, double mu) const;

    double dShapeFunctiondeta(size_t i, double epsilon, double eta, double mu) const;

    double dShapeFunctiondmu(size_t i, double epsilon, double eta, double mu) const;

    Eigen::Matrix<double, 24, 1> m_elementRestPosition;

    Eigen::Matrix<double, 6, 24> m_strain;
    Eigen::Matrix<double, 6, 24> m_stress;
    Eigen::Matrix<double, 6, 6> m_constitutiveMaterial;
};

} // namespace Physics

} // namespace SurgSim

#endif // SURGSIM_PHYSICS_FEM3DELEMENTCUBE_H