Imposing a biaxial displacement

[pierregehl]

Hi,

I am using a soil model (2D quad elements with PressureIndependMultiYield behavior) and I need to impose a progressive displacement on a given node.
The direction of the displacement needs to follow both directions (x and y).
I have tried to create two differents load patterns, using the sp command, and then running the analysis with a load control, but nothing happens (the analysis is running but the node does not move).

You'll find below a part of my tcl file :

-----------------------------------

set Hload $Weight
set IDctrlNode 4420
set IDctrlDOF1 1
set IDctrlDOF2 2
set Dmax1 [expr 20/sqrt(2)]
set Dmax2 [expr -20/sqrt(2)]
set Dincr1 [expr 0.01*$Dmax1]
set Dincr2 [expr 0.01*$Dmax2]

pattern Plain 2 Linear {
sp $IDctrlNode $IDctrlDOF1 1
}

pattern Plain 3 Linear {
sp $IDctrlNode $IDctrlDOF2 -1
}

integrator LoadControl 1
constraints Plain
numberer Plain
system SparseGeneral -piv

set Tol 1e-6
set maxNumIter 1000
set printFlag 1
set TestType EnergyIncr
test $TestType $Tol $maxNumIter $printFlag;

set algorithmType Newton
algorithm $algorithmType

analysis Static
analyze 100

----------------------------------

I think I have trouble using correctly the sp commmand.

Thank you very much for your help !

[silvia]

i would try it on a simple model, sdof system, first.

[pierregehl]

Hi,

It works ok now (I've replaced constraints Plain by constraints Transformation): I just hadn't noticed that this method required homogeneous single-point constraints.

thx anyway,

Pierre