int
ViscousDamper::setTrialStrain(double strain, double strainRate)
{
//all variables to the last commit
this->revertToLastCommit();
// Determine the strain rate and acceleration
//double dStrain = (strain - Tstrain);
double dVel, fd0, acc, vel1, vel0;
if (fabs(strainRate) == 0.0) { //static analysis
dVel = 0.0;
acc = 0.0;
} else {
//dVel = dStrain/ops_Dt;
dVel = strainRate;
acc = (dVel - TdVel)/ops_Dt;
}
double smin = pow(0.5,MaxHalf);
double s = 1.0;
double stot = 0.0;
double it = 0.0;
fd0 = Tstress;
double h, yt, eps;
vel0 = TdVel; // Velocity of the previous step.
while (it < 1.0) {
h = s * ops_Dt; // Time step
vel1 = vel0 + acc * h; // Velocity at the time step h
// Selection of Numerical Method to solve the ODE
if (NM == 1.0) {
DormandPrince(vel0, vel1, fd0, h, yt, eps);
}
if (NM == 2.0) {
ABM6(vel0, vel1, fd0, h, yt, eps);
}
if (NM == 3.0) {
ROS(vel0, vel1, fd0, h, yt, eps);
}
// Error check: Adaptive Step Size
if ((eps <= Tol) || (s == smin)) {
vel0 = vel1;
fd0 = yt;
stot = stot+s;
}else {
if (s > smin) {
s=0.5*s; // step gets smaller -now try this step again.
} else {
s=smin;
}
}
if (stot == 1.0) { // The total internal stepsize reached dt
it=1.0;
}
}
// Total Stress
Tstress = fd0;
Tstrain = strain;
TdVel = dVel;
Ttangent = 0.;
//// Total strain in the elastic part of the damper
//double Tstrains = fd0/K;
//
//// Total strain in the viscous part of the damper
// double Tstraind = strain - Tstrains;
return 0;
}
int
ViscousDamper::setTrialStrain(double strain, double strainRate)
{
//all variables to the last commit
this->revertToLastCommit();
// Determine the strain rate and acceleration
double Vel, fd0, acc, vel1, vel0;
if (fabs(strainRate) == 0.0) { //static analysis
Vel = 0.0;
acc = 0.0;
} else {
Vel = strainRate;
acc = (Vel - TVel)/ops_Dt;
}
double smin = pow(0.5,MaxHalf);
double s = 1.0;
double stot = 0.0;
double it = 0.0;
fd0 = Tstress;
double h, yt, eps, error;
vel0 = TVel; // Velocity of the previous step.
while (it < 1.0) { //iteration
h = s * ops_Dt; // Time step
vel1 = vel0 + acc * h; // Velocity at the time step h
// Selection of Numerical Method to solve the ODE
if (NM == 1.0) {
DormandPrince(vel0, vel1, fd0, h, yt, eps, error);
}
if (NM == 2.0) {
ABM6(vel0, vel1, fd0, h, yt, eps, error);
}
if (NM == 3.0) {
ROS(vel0, vel1, fd0, h, yt, eps, error);
}
// Error check: Adaptive Step Size
if ((eps <= RelTol) || (s == smin) || (fabs(error) <= AbsTol)) {
vel0 = vel1;
fd0 = yt;
stot = stot+s;
} else {
if (s > smin) {
s=0.5*s; // step gets smaller -now try this step again.
} else {
s=smin;
}
}
if (stot == 1.0) { // The total internal stepsize reached dt
it=1.0;
}
}
// Effect of gap start
if (LGap > 0.) {
double dStrain = (strain - Tstrain);
if ((fd0 > 0) && (Tstress < 0)) { //from negtive to positive
Tpugr = Tstrain + dStrain * fabs(fd0)/fabs(fd0 - Tstress); // aproximate displacement for gap initiation
Tnugr = 0.;
if (fabs(strain-Tpugr) < LGap) {
fd0 = 0.;
}
}
if ((fd0 < 0) && (Tstress > 0)) { //from positive to negative
Tnugr = Tstrain + dStrain * fabs(fd0)/fabs(fd0 - Tstress); // aproximate displacement for gap initiation
Tpugr = 0.;
if (fabs(strain-Tnugr) < LGap) {
fd0 = 0.;
}
}
// After gap inititon
if ((fabs(Tpugr) > 0.) && (Tstress == 0)) { //from negtive to positive
if ((strain > Tpugr) && ((strain-Tpugr) < LGap)) {
fd0 = 0.;
}
}
if ((fabs(Tnugr) > 0.) && (Tstress == 0)) { //from positive to negative
if ((strain < Tnugr) && ((strain-Tnugr) > -LGap)) {
fd0 = 0.;
}
}
}
// Effect of gap end
Tstress = fd0; // Stress
TVel = Vel;
Tstrain = strain;
return 0;
}
