void
KelvinChainSolidMaterial :: computeHiddenVars(GaussPoint *gp, TimeStep *tStep)
{
/*
* Updates hidden variables used to effectively trace the load history
*/
double betaMu;
double lambdaMu;
FloatArray help, SigmaVMu, deltaEps0, deltaSigma;
FloatMatrix D;
KelvinChainSolidMaterialStatus *status = static_cast< KelvinChainSolidMaterialStatus * >( this->giveStatus(gp) );
if ( !this->isActivated(tStep) ) {
help.resize(StructuralMaterial :: giveSizeOfVoigtSymVector( gp->giveMaterialMode() ) );
help.zero();
for ( int mu = 1; mu <= nUnits; mu++ ) {
status->letTempHiddenVarsVectorBe(mu, help);
}
return;
}
help = status->giveTempStrainVector(); // gives updated strain vector (at the end of time-step)
help.subtract( status->giveStrainVector() ); // strain increment in current time-step
// Subtract the stress-independent part of strain
this->computeStressIndependentStrainVector(deltaEps0, gp, tStep, VM_Incremental);
if ( deltaEps0.giveSize() ) {
help.subtract(deltaEps0); // should be equal to zero if there is no stress change during the time-step
}
this->giveUnitStiffnessMatrix(D, gp, tStep);
help.times( this->giveEModulus(gp, tStep) );
deltaSigma.beProductOf(D, help);
for ( int mu = 1; mu <= nUnits; mu++ ) {
betaMu = this->computeBetaMu(gp, tStep, mu);
lambdaMu = this->computeLambdaMu(gp, tStep, mu);
help = deltaSigma;
help.times(lambdaMu);
SigmaVMu = status->giveHiddenVarsVector(mu);
if ( SigmaVMu.giveSize() ) {
SigmaVMu.times(betaMu);
SigmaVMu.add(help);
status->letTempHiddenVarsVectorBe(mu, SigmaVMu);
} else {
status->letTempHiddenVarsVectorBe(mu, help);
}
}
}
void
KelvinChainSolidMaterial :: giveEigenStrainVector(FloatArray &answer, GaussPoint *gp, TimeStep *tStep, ValueModeType mode)
//
// computes the strain due to creep at constant stress during the increment
// (in fact, the INCREMENT of creep strain is computed for mode == VM_Incremental)
//
{
int mu;
double betaMu;
double v;
FloatArray *sigmaVMu = NULL, reducedAnswer, help;
FloatMatrix C;
KelvinChainSolidMaterialStatus *status = static_cast< KelvinChainSolidMaterialStatus * >( this->giveStatus(gp) );
if ( (tStep->giveIntrinsicTime() < this->castingTime) ) {
OOFEM_ERROR("Attempted to evaluate creep strain for time lower than casting time");
}
if ( this->EparVal.isEmpty() ) {
this->updateEparModuli(0., gp, tStep); // stiffnesses are time independent (evaluated at time t = 0.)
}
if ( mode == VM_Incremental ) {
for ( mu = 1; mu <= nUnits; mu++ ) {
betaMu = this->computeBetaMu(gp, tStep, mu);
sigmaVMu = & status->giveHiddenVarsVector(mu); // JB
if ( sigmaVMu->isNotEmpty() ) {
help.zero();
help.add(* sigmaVMu);
help.times( ( 1.0 - betaMu ) / this->giveEparModulus(mu) );
reducedAnswer.add(help);
}
}
if ( sigmaVMu->isNotEmpty() ) {
help = reducedAnswer;
this->giveUnitComplianceMatrix(C, gp, tStep);
reducedAnswer.beProductOf(C, help);
v = this->computeSolidifiedVolume(gp, tStep);
reducedAnswer.times(1. / v);
}
answer = reducedAnswer;
} else {
/* error - total mode not implemented yet */
OOFEM_ERROR("mode is not supported");
}
}
void
KelvinChainSolidMaterial :: giveEigenStrainVector(FloatArray &answer, MatResponseForm form,
GaussPoint *gp, TimeStep *atTime, ValueModeType mode)
//
// computes the strain due to creep at constant stress during the increment
// (in fact, the INCREMENT of creep strain is computed for mode == VM_Incremental)
//
{
int mu;
double betaMu;
double v;
FloatArray *sigmaVMu, reducedAnswer, help;
FloatMatrix C;
KelvinChainSolidMaterialStatus *status = ( KelvinChainSolidMaterialStatus * ) this->giveStatus(gp);
if ( mode == VM_Incremental ) {
for ( mu = 1; mu <= nUnits; mu++ ) {
betaMu = this->computeBetaMu(gp, atTime, mu);
sigmaVMu = status->giveHiddenVarsVector(mu);
if ( sigmaVMu ) {
help.zero();
help.add(* sigmaVMu);
help.times( ( 1.0 - betaMu ) / this->giveEparModulus(mu) );
reducedAnswer.add(help);
}
}
if ( sigmaVMu ) {
help = reducedAnswer;
this->giveUnitComplianceMatrix(C, ReducedForm, gp, atTime);
reducedAnswer.beProductOf(C, help);
v = this->computeSolidifiedVolume(gp, atTime);
reducedAnswer.times(1. / v);
}
if ( form == ReducedForm ) {
answer = reducedAnswer;
return;
}
// expand the strain to full form if requested
( ( StructuralCrossSection * ) gp->giveCrossSection() )->
giveFullCharacteristicVector(answer, gp, reducedAnswer);
} else {
/* error - total mode not implemented yet */
_error("giveEigenStrainVector - mode is not supported");
}
}
void
KelvinChainSolidMaterial :: updateYourself(GaussPoint *gp, TimeStep *tNow)
{
/*
* Updates hidden variables used to effectively trace the load history
*/
double betaMu;
double lambdaMu;
FloatArray help, *SigmaVMu, deltaEps0, deltaSigma;
FloatMatrix D;
KelvinChainSolidMaterialStatus *status = ( KelvinChainSolidMaterialStatus * ) this->giveStatus(gp);
help = status->giveTempStrainVector(); // gives updated strain vector (at the end of time-step)
help.subtract( status->giveStrainVector() ); // strain increment in current time-step
// Subtract the stress-independent part of strain
this->computeStressIndependentStrainVector(deltaEps0, gp, tNow, VM_Incremental);
if ( deltaEps0.giveSize() ) {
help.subtract(deltaEps0); // should be equal to zero if there is no stress change during the time-step
}
this->giveUnitStiffnessMatrix(D, ReducedForm, gp, tNow);
help.times( this->giveEModulus(gp, tNow) );
deltaSigma.beProductOf(D, help);
for ( int mu = 1; mu <= nUnits; mu++ ) {
betaMu = this->computeBetaMu(gp, tNow, mu);
lambdaMu = this->computeLambdaMu(gp, tNow, mu);
help = deltaSigma;
help.times(lambdaMu);
SigmaVMu = status->giveHiddenVarsVector(mu);
if ( SigmaVMu ) {
SigmaVMu->times(betaMu);
SigmaVMu->add(help);
} else {
status->letHiddenVarsVectorBe( mu, ( new FloatArray(help) ) );
}
}
status->updateYourself(tNow);
}