# yade-users team mailing list archive

## [Question #700144]: Problems in yade and oofem triaxial test simulations

```New question #700144 on Yade:

Hello all,
I'm encountering a problem when using yade and oofem for triaxial test simulations.
In the model, I simulated the rubber membrane with oofem and applied confine pressure with nodal forces (σ3=600kPa). However, when the axial strain is about 1%, the rubber membrane starts to rotate in one direction and an excessive amount of deformation is generated at the same time. Here is how I apply the nodal force：
In the model, the height of the specimen is 0.6m, the nodal force is 423.9N.

global vsc
vsc = [v.coords for v in self.femMesh.vertices]
for i,v in enumerate(self.forces):
angle = math.atan2(vsc[i][1],vsc[i][0])
D = (vsc[i][0]**2)+(vsc[i][1]**2)
angle1=vsc[i][0]/0.16699999
angle2=vsc[i][1]/0.16699999
if D > 0.024 and vsc[i][2] < 0.589:
#self.forces[i] = self.forces[i]+Vector3(-423.9*math.cos(angle),-423.9*math.sin(angle),0)
self.forces[i] = self.forces[i]+Vector3(-423.9*angle1,-423.9*angle2,0)

Is there something wrong with the way I apply the nodal force?

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