// Traction law - assume trianglar shape with unloading from down slope back to the origin
void CubicTraction::CrackTractionLaw(CrackSegment *cs,double nCod,double tCod,double dx,double dy,double area)
{
double Tn=0.,Tt=0.,GI=0.,GII=0.;
double *upeak =(double *)cs->GetHistoryData();
// normal force and GI (only if open)
if(nCod>0.)
{ // is it failed?
if(nCod>delIc)
{ cs->SetMatID(0); // then debonded
GI = JIc;
}
else
{ if(nCod>upeak[0]) upeak[0]=nCod; // new peak reached
double keff=kI1*(delIc-upeak[0])*(delIc-upeak[0]);
Tn=keff*nCod;
// get GI for failure law
double d=nCod/delIc;
GI=JIc*d*d*(6.-8.*d+3.*d*d); // N/m
}
}
// shear force and GII always
// is it failed?
double absTCod=fabs(tCod);
if(absTCod>delIIc)
{ cs->SetMatID(0); // then debonded
GII = JIIc;
}
else
{ if(absTCod>upeak[1]) upeak[1]=absTCod; // new peak reached in either direction
double keff=kII1*(delIIc-upeak[1])*(delIIc-upeak[1]);
Tt=keff*tCod;
// get GII for failure law
double d=tCod/delIIc;
GII=JIIc*d*d*(6.-8.*d+3.*d*d); // N/m
}
// failure criterion
if(cs->MatID()<0)
{ // it failed above in pure mode
ReportDebond(mtime, cs, GI/(GI+GII),GI+GII);
Tn = 0.; // turn off in tractions, if calculated
Tt = 0.;
}
else if(nmix>0)
{ // mixed mode failure? (nmix<=0 uses infinity which means fails when either COD becomes critical)
if(pow(GI/JIc,nmix)+pow(GII/JIIc,nmix) > 1)
{ cs->SetMatID(0); // now debonded
ReportDebond(mtime,cs,GI/(GI+GII),GI+GII);
Tn=0.;
Tt=0.;
}
}
// force is traction times area projected onto x-y plane
cs->tract.x=area*(Tn*dy - Tt*dx);
cs->tract.y=area*(-Tn*dx - Tt*dy);
}
// Traction law - assume trianglar shape with unloading from down slope back to the origin
void TrilinearTraction::CrackTractionLaw(CrackSegment *cs,double nCod,double tCod,double dx,double dy,double area)
{
double Tn=0.,Tt=0.,GI=0.,GII=0.;
double *upeak =(double *)cs->GetHistoryData();
// normal force and GI (only if open)
if(nCod>0.)
{ // is it failed?
if(nCod>delIc)
{ cs->SetMatID(0); // then debonded
GI = JIc;
}
else
{ if(nCod>upeak[0]) upeak[0]=nCod; // new peak reached
double keff;
if(upeak[0]<=uI2)
{ if(break1is2I)
keff = stress1/upeak[0];
else
keff = (sI2*(upeak[0]-umidI)+stress1*(uI2-upeak[0]))/((uI2-umidI)*upeak[0]);
}
else
keff = sI2*(delIc-upeak[0])/((delIc-uI2)*upeak[0]);
Tn = keff*nCod;
// get GI for failure law
if(nCod<umidI)
{ // note that initial linear softening never because umidI=0
GI = 0.5*kI1*nCod*nCod;
}
else if(nCod<=uI2)
{ if(break1is2I)
GI = 0.5*stress1*umidI;
else
{ double s2 = (sI2*(nCod-umidI)+stress1*(uI2-nCod))/(uI2-umidI);
GI = 0.5*(nCod*stress1 + s2*(nCod - umidI));
}
}
else
{ double s2 = (delIc-nCod)*sI2/(delIc-uI2);
GI = 0.5*(stress1*uI2 + sI2*(nCod-umidI) + s2*(nCod-uI2));
}
}
}
// shear force and GII always
// is it failed?
double absTCod=fabs(tCod);
if(absTCod>delIIc)
{ cs->SetMatID(0); // then debonded
GII = JIIc;
}
else if(absTCod>0.)
{ if(absTCod>upeak[1]) upeak[1]=absTCod; // new peak reached
double keff;
if(upeak[1]<=uII2)
{ if(break1is2II)
keff = stress2/upeak[1];
else
keff = (sII2*(upeak[1]-umidII)+stress2*(uII2-upeak[1]))/((uII2-umidII)*upeak[1]);
}
else
keff = sII2*(delIIc-upeak[1])/((delIIc-uII2)*upeak[1]);
Tt = keff*tCod;
// get GII for failure law
if(absTCod<umidII)
{ // note that initial linear softening never because umidI=0
GII = 0.5*kII1*tCod*tCod;
}
else if(absTCod<=uII2)
{ if(break1is2II)
GII = 0.5*stress2*umidII;
else
{ double s2 = (sII2*(absTCod-umidII)+stress2*(uII2-absTCod))/(uII2-umidII);
GII = 0.5*(absTCod*stress2 + s2*(absTCod - umidII));
}
}
else
{ double s2 = (delIIc-absTCod)*sII2/(delIIc-uII2);
GII = 0.5*(stress2*uII2 + sII2*(absTCod-umidII) + s2*(absTCod-uII2));
}
}
// failure criterion
if(cs->MatID()<0)
{ // it failed above in pure mode
ReportDebond(mtime, cs, GI/(GI+GII),GI+GII);
Tn = 0.; // turn off in tractions, if calculated
Tt = 0.;
}
else if(nmix>0)
{ // mixed mode failure? (nmix<=0 uses infinity which means fails when either COD becomes critical)
if(pow(GI/JIc,nmix)+pow(GII/JIIc,nmix) > 1)
{ cs->SetMatID(0); // now debonded
ReportDebond(mtime,cs,GI/(GI+GII),GI+GII);
Tn = 0.; // turn off in tractions, if calculated
Tt = 0.;
}
}
// force is traction times area projected onto x-y plane
cs->tract.x = area*(Tn*dy - Tt*dx);
cs->tract.y = area*(-Tn*dx - Tt*dy);
}
