FEActiveFiberStressUC.cpp

/*This file is part of the FEBio source code and is licensed under the MIT license
listed below.

See Copyright-FEBio.txt for details.

Copyright (c) 2021 University of Utah, The Trustees of Columbia University in
the City of New York, and others.

Permission is hereby granted, free of charge, to any person obtaining a copy
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#include "stdafx.h"
#include "FEActiveFiberStressUC.h"
#include "FEElasticMaterial.h"
#include <FECore/log.h>

void FEActiveFiberStressUC::Data::Serialize(DumpStream& ar)
{
	FEMaterialPointData::Serialize(ar);
	ar & m_lamp;
}

//=====================================================================================

BEGIN_FECORE_CLASS(FEActiveFiberStressUC, FEUncoupledMaterial);
	ADD_PARAMETER(m_smax, "smax")->setUnits(UNIT_PRESSURE);
	ADD_PARAMETER(m_ac, "activation");

	ADD_PROPERTY(m_stl, "stl", FEProperty::Optional);
	ADD_PROPERTY(m_stv, "stv", FEProperty::Optional);

	ADD_PROPERTY(m_Q, "mat_axis")->SetFlags(FEProperty::Optional);

END_FECORE_CLASS();

FEActiveFiberStressUC::FEActiveFiberStressUC(FEModel* fem) : FEUncoupledMaterial(fem)
{
	m_smax = 0.0;
	m_ac = 0.0;

	m_stl = nullptr;
	m_stv = nullptr;
}

mat3ds FEActiveFiberStressUC::DevStress(FEMaterialPoint& mp)
{
	FEElasticMaterialPoint& pt = *mp.ExtractData<FEElasticMaterialPoint>();

	double dt = 0.0;

	mat3d& F = pt.m_F;
	double J = pt.m_J;
	double J13 = pow(J, 1.0 / 3.0);

	mat3d Q = GetLocalCS(mp);

	vec3d a0 = Q.col(0);

	vec3d a = F*a0;
	double lam = a.unit() / J13;

	double stl = (m_stl ? m_stl->value(lam) : 1.0);
	double v = 0;// (lam - lamp) / dt;
	double stv = (m_stv ? m_stv->value(v) : 1.0);

	mat3ds A = dyad(a);

	double sf = m_ac*m_smax*stl*stv;

	return A.dev()*(sf / J);
}

tens4ds FEActiveFiberStressUC::DevTangent(FEMaterialPoint& mp)
{
	FEElasticMaterialPoint& pt = *mp.ExtractData<FEElasticMaterialPoint>();

	double dt = 1.0;

	mat3d& F = pt.m_F;
	double J = pt.m_J;
	double J13 = pow(J, 1.0 / 3.0);

	mat3d Q = GetLocalCS(mp);

	vec3d a0 = Q.col(0);

	vec3d a = F*a0;
	double lam = a.unit() / J13;

	mat3ds A = dyad(a);

	mat3dd I(1.0);
	tens4ds IxI = dyad1s(I);
	tens4ds I4 = dyad4s(I);

	tens4ds AA = dyad1s(A.dev());
	tens4ds AI = dyad1s(A, I);

	double stl = (m_stl ? m_stl->value(lam) : 1.0);
	double v = 0;// (lam - lamp) / dt;
	double stv = (m_stv ? m_stv->value(v) : 1.0);

	double dstl = (m_stl ? m_stl->derive(lam) : 0.0);
	double dstv = (m_stv ? m_stv->derive(v) / dt : 0.0);

	double sf = m_ac*m_smax*stl*stv;
	double sf_l = m_ac*m_smax*(dstl*stv + stl*dstv);

	tens4ds cff = AA*(lam*sf_l - 2.0*sf);
	tens4ds cf = (AI - I4 - IxI/3.0)*(2.0*sf/3.0);

	tens4ds c = (cff - cf) / J;

	return c;
}