FEBio/FEDamageNeoHookean.h

#pragma once
#include "FEElasticMaterial.h"

//-----------------------------------------------------------------------------
// This material is a first attempt to include damage in hyper-elastic materials.
// It assumes the simple damage model as defined in Simo, CMAME 60 (1987), 153-173

//-----------------------------------------------------------------------------
// We first define a material point that stores the damage variable.
class FEDamageMaterialPoint : public FEMaterialPoint
{
public:
        FEDamageMaterialPoint(FEMaterialPoint *pt) : FEMaterialPoint(pt) {}

        FEMaterialPoint* Copy()
        {
                FEDamageMaterialPoint* pt = new FEDamageMaterialPoint(*this);
                if (m_pt) pt->m_pt = m_pt->Copy();
                return pt;
        }

        void Init(bool bflag)
        {
                FEElasticMaterialPoint& pt = *m_pt->ExtractData<FEElasticMaterialPoint>();
                if (bflag)
                {
                        // intialize data to zero
                        m_Emax = 0;
                        m_Etrial = 0;
                        m_D = 1;
                }
                else
                {
                        m_Emax = max(m_Emax, m_Etrial);
                }

                // don't forget to intialize the nested data
                if (m_pt) m_pt->Init(bflag);
        }

        void Serialize(DumpFile& ar)
        {
                if (ar.IsSaving())
                {
                        ar << m_Emax;
                }
                else
                {
                        ar >> m_Emax;
                }
        }

public:
        double  m_Etrial;               
        double  m_Emax;                 
        double  m_D;                    
};

//-----------------------------------------------------------------------------
class FEDamageNeoHookean : public FEElasticMaterial
{
public:
        FEDamageNeoHookean(void);

public:
        double  m_E;    
        double  m_v;    

        double  m_alpha;        
        double  m_beta;         

protected:
        double  m_lam;
        double  m_mu;

public:
        virtual mat3ds Stress(FEMaterialPoint& pt);

        virtual tens4ds Tangent(FEMaterialPoint& pt);

        void Init();

        double BulkModulus() { return m_E/(3.0*(1.0 - 2.0*m_v));}

        // returns a pointer to a new material point object
        virtual FEMaterialPoint* CreateMaterialPointData() 
        { 
                return new FEDamageMaterialPoint(new FEElasticMaterialPoint);
        }

        // calculate damage reduction factor
        double Damage(FEMaterialPoint& pt);

        // declare as registered
        DECLARE_REGISTERED(FEDamageNeoHookean);

        // declare the parameter list
        DECLARE_PARAMETER_LIST();
};