void
MisesMatNl :: give1dStressStiffMtrx(FloatMatrix &answer, MatResponseMode mode, GaussPoint *gp, TimeStep *tStep)
{
answer.resize(1, 1);
answer.zero();
LinearElasticMaterial *lmat = this->giveLinearElasticMaterial();
double E = lmat->give('E', gp);
double nlKappa;
MisesMatNlStatus *status = static_cast< MisesMatNlStatus * >( this->giveStatus(gp) );
double kappa = status->giveCumulativePlasticStrain();
double tempKappa = status->giveTempCumulativePlasticStrain();
double tempDamage = status->giveTempDamage();
double damage = status->giveDamage();
answer.at(1, 1) = ( 1 - tempDamage ) * E;
if ( mode != TangentStiffness ) {
return;
}
if ( tempKappa <= kappa ) { // elastic loading - elastic stiffness plays the role of tangent stiffness
return;
}
// === plastic loading ===
const FloatArray &stressVector = status->giveTempEffectiveStress();
double stress = stressVector.at(1);
answer.at(1, 1) = ( 1. - tempDamage ) * E * H / ( E + H );
if ( tempDamage > damage ) {
this->computeCumPlasticStrain(nlKappa, gp, tStep);
answer.at(1, 1) = answer.at(1, 1) - ( 1 - mm ) * computeDamageParamPrime(nlKappa) * E / ( E + H ) * stress * sgn(stress);
}
}
int
MisesMatNl :: giveLocalNonlocalStiffnessContribution(GaussPoint *gp, IntArray &loc, const UnknownNumberingScheme &s,
FloatArray &lcontrib, TimeStep *atTime)
{
int nrows, nsize, i, j;
double sum, nlKappa, damage, tempDamage, dDamF;
MisesMatNlStatus *status = ( MisesMatNlStatus * ) this->giveStatus(gp);
StructuralElement *elem = ( StructuralElement * )( gp->giveElement() );
FloatMatrix b;
FloatArray stress;
this->computeCumPlasticStrain(nlKappa, gp, atTime);
damage = status->giveDamage();
tempDamage = status->giveTempDamage();
if ( ( tempDamage - damage ) > 0 ) {
elem->giveLocationArray(loc, EID_MomentumBalance, s);
status->giveTempEffectiveStress(stress);
elem->computeBmatrixAt(gp, b);
dDamF = computeDamageParamPrime(nlKappa);
nrows = b.giveNumberOfColumns();
nsize = stress.giveSize();
lcontrib.resize(nrows);
for ( i = 1; i <= nrows; i++ ) {
sum = 0.0;
for ( j = 1; j <= nsize; j++ ) {
sum += b.at(j, i) * stress.at(j);
}
lcontrib.at(i) = sum * mm * dDamF;
}
}
return 1;
}
int
MisesMatNl :: giveLocalNonlocalStiffnessContribution(GaussPoint *gp, IntArray &loc, const UnknownNumberingScheme &s,
FloatArray &lcontrib, TimeStep *tStep)
{
double nlKappa, damage, tempDamage, dDamF;
MisesMatNlStatus *status = static_cast< MisesMatNlStatus * >( this->giveStatus(gp) );
StructuralElement *elem = static_cast< StructuralElement * >( gp->giveElement() );
FloatMatrix b;
this->computeCumPlasticStrain(nlKappa, gp, tStep);
damage = status->giveDamage();
tempDamage = status->giveTempDamage();
if ( ( tempDamage - damage ) > 0 ) {
const FloatArray &stress = status->giveTempEffectiveStress();
elem->giveLocationArray(loc, s);
elem->computeBmatrixAt(gp, b);
dDamF = computeDamageParamPrime(nlKappa);
lcontrib.clear();
lcontrib.plusProduct(b, stress, mm * dDamF);
}
return 1;
}
