Claddings creating unstability type 2

[Anonymous]

Hello,

I created a model of beams and columns with some pinned and fixed connections.

I first defined loads on these beams and columns and everythings works fine.
Then I defined claddings to apply planar loads and an unstability type 2 appears one noad (always the same).

If I suppress the cladding next to these node, everything works again.

More surprising, if I keep this problematic cladding but create a new load case, the unstabilty happens to disappear, but reappear when I create a second new one. 

I checked and the four nodes defining the cladding really looks in the same plan.

Do you have any idea how to solve this ?

Regards,

Charles TACHOT,
ECM

[Artur.Kosakowski]

Is it the same when you set the solver to Skyline? 

If you find your post answered press the Accept as Solution button please. This will help other users to find solutions much faster. Thank you.

[Anonymous]

With solver skyline the unstability turns to type 1.

By the way, I forgot to say that, despite the unstability results look quite good.

Regards,

Charles

[Artur.Kosakowski]

Try to define a unit force or moment in the reported location for the reported d.o.f and check values of max. displacements and rotations. I don't think that you can ignore the instability of type 1 reported by the Skyline solver.