About Pinching4 negative gradient setting

[shiro]

Hello!

In the Pinching4 setting, setting ePf4 and eNf4 to plus will succeed.
(ePd4,ePf4) , (eNd4,eNf4)

Setting ePf4 and eNf4 to negative gradient will result in an error
because we want to consider the negative gradient.

set pEnvelopeStress [list 31.19e3 55.00e3 80.00e3 32.00e3]
set nEnvelopeStress [list -31.19e3 -55.00e3 -80.00e3 -32.00e3]

When setting a negative gradient in the Pinching4 model,
how should the 4th node be set in the following example?

I would appreciate it if you could answer.


proc ch1 {matID} {

#stress1 stress2 stress3 stress4
set pEnvelopeStress [list 31.19e3 55.00e3 80.00e3 1200.00e3]
set nEnvelopeStress [list -31.19e3 -55.00e3 -80.00e3 -1200.00e3]

#strain1 strain2 strain3 strain4
set pEnvelopeStrain [list [expr 1.35] [expr 4.0] [expr 6.78] [expr 131.22]]
set nEnvelopeStrain [list [expr -1.35] [expr -4.00] [expr -6.78] [expr -131.22]]

#Pos_env. Neg_env.
set rDisp [list 0.5 0.5]

#Pos_env. Neg_env.
set rForce [list 0.25 0.25]

#Pos_env. Neg_env.
set uForce [list -0.05 -0.05]

#gammaK1 gammaK2 gammaK3 gammaK4 gammaKLimit
set gammaK [list 0.0 0.0 0.0 0.0 0.0]

#gammaD1 gammaD2 gammaD3 gammaD4 gammaDLimit
set gammaD [list 0.0 0.0 0.0 0.0 0.0]

#gammaF1 gammaF2 gammaF3 gammaF4 gammaFLimit
set gammaF [list 0.0 0.0 0.0 0.0 0.0]

set gammaE 100

set dam "cycle"

uniaxialMaterial Pinching4 $matID [lindex $pEnvelopeStress 0] [lindex $pEnvelopeStrain 0] [lindex $pEnvelopeStress 1] [lindex $pEnvelopeStrain 1] [lindex $pEnvelopeStress 2] [lindex $pEnvelopeStrain 2] [lindex $pEnvelopeStress 3] [lindex $pEnvelopeStrain 3] [lindex $nEnvelopeStress 0] [lindex $nEnvelopeStrain 0] [lindex $nEnvelopeStress 1] [lindex $nEnvelopeStrain 1] [lindex $nEnvelopeStress 2] [lindex $nEnvelopeStrain 2] [lindex $nEnvelopeStress 3] [lindex $nEnvelopeStrain 3] [lindex $rDisp 0] [lindex $rForce 0] [lindex $uForce 0] [lindex $rDisp 1] [lindex $rForce 1] [lindex $uForce 1] [lindex $gammaK 0] [lindex $gammaK 1] [lindex $gammaK 2] [lindex $gammaK 3] [lindex $gammaK 4] [lindex $gammaD 0] [lindex $gammaD 1] [lindex $gammaD 2] [lindex $gammaD 3] [lindex $gammaD 4] [lindex $gammaF 0] [lindex $gammaF 1] [lindex $gammaF 2] [lindex $gammaF 3] [lindex $gammaF 4] $gammaE $dam

}