zero pivot error in the msg file/abaqus

[elcv]

i have two separate membranes and i link them with beam elements
but i get this error in the msg file:
WARNING: SOLVER PROBLEM. ZERO PIVOT WHEN PROCESSING NODE 142 INSTANCE
PART-1-1 D.O.F. 6
Typically a zero pivot is associated with an overconstraint in the model.
However, Abaqus was not able to indentify any chains of constraints that might
lead to an overconstraint at this node. This suggests that the model might be
in fact insufficiently constrained in this particular degree of freedom.
Please check the constraints used in this model.
how can i solve it
plz help

 

[johnhors]

Try running a modal analysis. This will identify any rigid body modes with zero (or very near to zero) frequencies, the mode shapes of which will give a visual representation of any under constrained mechanisms in the model.

http://www.Roshaz.com

quality, cost effective FEA solutions

 

[elcv]

i have detected the nodes which are over constrained but the thing is that i cannot understand in my input file where is the problem since i have define all my nodes by the same way and only few have the problem. I have defined the beam links starting from the nodes of the bottom membrane and ending to the nodes of the top membrane

 

[btrueblood]

By "membrane", do you mean shell elements?

Are the beams making rigid connections to the shell nodes?

Can you try making simple support connections (hinged) to the shell nodes?

 

[elcv]

i tried hinge but still the same warnings

 

[TomaszK]

Does the membrane element have all DOF's active? If not, then beams could rotate alone axis. Try fix DOF 6 at beams.

breg
Tomasz

 

[lakshmi2011]

Did you try using PIN element to connect the membrane elements