common error on Femap: negatives pivots

[Maestro50]

Hello , I am new on Femap
I've often the same error on femap : negative or excessive pivot on the DOF listed ...
I know it's a constraint problem but I don't know how to fix it.

What I 'm supposed to do if the error message says " Excessive pivot on the DOF R3 of the point 42"

Thanks

 

[rb1957]

are you using shell elements ? isn't R3 the "drilling" freedom (ie = RZ) ? i think there's a param card (K6ROT?) that'll get rid of these messages.

Quando Omni Flunkus Moritati

 

[Maestro50]

I'm working with beam element so I don't think it's the drilling freedom.

It's a simple model : One beam with the right end fixed and connected (at the left end) to a second beam with a Cbush element . Then I apply a torque to the right end of the second beam.
I want to bend the strucure (like closing a book)

 

[rb1957]

i suspect it's a problem with your Cbush ... beam1 (fixed to ground) has to be ok, so it has to be beam2 (mind you the error codes should be telling you this).

you're applying torque, and you want the beams to "close like a book"? does "torque" mean a load (in-plane) causing torque about the axis where the beams join ? you're not running linear statics are you ? (since you have a dynamic problem)

Quando Omni Flunkus Moritati

 

[Maestro50]

yes , i'm not running a linear statics analyse .

I tried applying a load but I have the same error message and I don't know how to follow the displacement of the beam. Then I tried with a torque.

 

[rb1957]

try the tutorials ... i know there are issues with beams and non-linear problems

Quando Omni Flunkus Moritati

 

[mrfemap]

Please post your FEMAP model, we'll figure it out -

Mark.

 

[Naffoussi]

Hi,

Check your units coherence (Material: young modulus...) and the C-BUSH stiffness you defined on the property.


Regards.