void
M1Material :: giveRealStressVector_PlaneStress(FloatArray &answer,
GaussPoint *gp,
const FloatArray &totalStrain,
TimeStep *tStep)
{
int i, imp;
FloatArray sigmaN, deps, sigmaNyield;
double depsN, epsN;
answer.resize(3);
answer.zero();
sigmaNyield.resize(nmp);
sigmaNyield.zero();
M1MaterialStatus *status = static_cast< M1MaterialStatus * >( this->giveStatus(gp) );
this->initTempStatus(gp);
sigmaN = status->giveNormalMplaneStresses();
if ( sigmaN.giveSize() < nmp ) {
sigmaN.resize(nmp);
sigmaN.zero();
}
deps.beDifferenceOf( totalStrain, status->giveStrainVector() );
for ( imp = 1; imp <= nmp; imp++ ) {
depsN = N.at(imp, 1) * deps.at(1) + N.at(imp, 2) * deps.at(2) + N.at(imp, 3) * deps.at(3);
epsN = N.at(imp, 1) * totalStrain.at(1) + N.at(imp, 2) * totalStrain.at(2) + N.at(imp, 3) * totalStrain.at(3);
sigmaN.at(imp) += EN * depsN;
double sy = EN * ( s0 + HN * epsN ) / ( EN + HN ); // current microplane yield stress
if ( sy < 0. ) {
sy = 0.;
}
if ( sigmaN.at(imp) > sy ) {
sigmaN.at(imp) = sy;
}
sigmaNyield.at(imp) = sy;
for ( i = 1; i <= 3; i++ ) {
answer.at(i) += N.at(imp, i) * sigmaN.at(imp) * mw.at(imp);
}
}
// update status
status->letTempStrainVectorBe(totalStrain);
status->letTempNormalMplaneStressesBe(sigmaN);
status->letNormalMplaneYieldStressesBe(sigmaNyield);
status->letTempStressVectorBe(answer);
}
int
M1Material :: giveIPValue(FloatArray &answer, GaussPoint *gp, InternalStateType type, TimeStep *tStep)
{
M1MaterialStatus *status = static_cast< M1MaterialStatus * >( this->giveStatus(gp) );
if ( type == IST_PlasticStrainTensor ) {
// plastic strain is computed as total strain minus elastic strain
// (note that integration of microplane plastic strains would give a different result)
answer = status->giveStrainVector();
FloatArray sig = status->giveStressVector();
double aux = nu * ( sig.at(1) + sig.at(2) + sig.at(3) );
double G = E / ( 2. * ( 1. + nu ) );
answer.at(1) -= ( ( 1. + nu ) * sig.at(1) - aux ) / E;
answer.at(2) -= ( ( 1. + nu ) * sig.at(2) - aux ) / E;
answer.at(3) -= ( ( 1. + nu ) * sig.at(3) - aux ) / E;
answer.at(4) -= sig.at(4) / G;
answer.at(5) -= sig.at(5) / G;
answer.at(6) -= sig.at(6) / G;
return 1;
} else {
return StructuralMaterial :: giveIPValue(answer, gp, type, tStep);
}
}
