Find hanging 1D elements in Femap

[Aero_guy5]

Is there a good way to reliably find all 'hanging' 1D elements? I have not found a good way within Femap. Maybe a job for API, but other competing tools have it built-in.

Different ways to accomplish this: select all nodes that are attached to only one element, select all elements that are only connected to one other element, etc. Does Femap have this functionality? Thanks!

 

[rb1957]

wouldn't "free edge" detect this ?

Wait for Blaise to reply, to tell you how to do it !

another day in paradise, or is paradise one day closer ?

 

[Aero_guy5]

Would love to get a response from the legend himself!

I don't think showing free edges does find it. That's more of a 2D and 3D element free edge finding tool. For 1D elements, a list of dangling nodes would be ideal for error checking. Seems like a reasonable thing for API maybe, but I'd expect built-in functionality. I know Hypermesh does this; hoping it is not missing from Femap...

 

[BlasMolero]

Dear Aero5,
You can always run a SOL103 modal/eigenvalue analysis and animate the rigid body modes with value 0 Hz, this is a reliable way to identify elements that are not properly constrained!!.
Best regards,
Blas.

~~~~~~~~~~~~~~~~~~~~~~
Blas Molero Hidalgo
Ingeniero Industrial
Director

IBERISA
48004 BILBAO (SPAIN)
WEB:

http://www.iberisa.com

Blog de FEMAP & NX Nastran:

http://iberisa.wordpress.com/

 

[ThomasH]

Hi

Could you perhaps explain a bit more about what you mean by "hanging 1D elements"?

When I see you description "nodes attached to only one element" or "elements attached to only one other elements". If you work with a beam model you will have those conditions at every beam end. And that is usually not an issue for neither the model nor the solver.

If it is unconstrained or not properly constrained elements that is the issue, I think BlasMoleros approach should work fine. I have used it myself on several occasions. I often use eigenvalue analysis to test that a model responds as expected.

But since there is some functionality in Hypermesh it would be interesting to know what the issue is.

Best regards

Thomas

 

[Aero_guy5]

Thanks Blas and Thomas for the responses.

To be a little more specific, I'm talking about massless beam elements and RBE elements. These are often used for connectors to represent bolted joints and the like, but sometimes if you are revising parts and changing the mesh on one side of the joint, you might mistakenly not re-connect all the beam or RBE elements. Since they have no mass, Sol103 won't show them. Also, it is possible to have 'old' nodes attached to an RBE2 or RBE3 element that used to connect to an 'old' version of one side of the joint, but really now that RBE should no longer reference the orphan node and the node itself should be deleted. Finding those orphan nodes that are remaining attached to only one element is quite tricky.

This most often happens when using the meshing toolbox to revise a portion of a mesh that has RBEs or beam elements used for connections. Femap will give a warning in the message window that the RBEs may not have reconnected properly and to manually check them, but it's not very helpful to just say that without a tool to specifically find those broken connectors.