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Boundary Conditions are applied to geometry having partial association of nodes and elements

Experimenter
Experimenter

Hello,

 

I have no idea why, but lately I'm having the warning message below quite often.

 

 

The following Boundary Conditions are applied to geometry having partial association of nodes and elements.

Symmetric(1)

This may lead to unexpected solution results.

 

Some times with Contacts.

 

My whole simulation is composed of CHEXA(20) and CETRA(10) elements.

 

I'm using NX10. I never had this warning messages in previous versions.

 

6 REPLIES

Re: Boundary Conditions are applied to geometry having partial association of nodes and elements

Siemens Phenom Siemens Phenom
Siemens Phenom

The message is indicating that portions of the geometry that the boundary condition is applied to has no related nodes/elements. For example, say you 2D mesh a face, then delete the elements that are connected to a vertex of the face. This message is highlighting that the vertex has no related node. So, there is partial mesh associativity in terms of the edges that are connected to the vertex that no longer has a node.

 

Did you do any manual mesh operations that deleted nodes/elements? Did you merge coincident nodes? If so, you may have created partial mesh association with respect to the geometry. The mesh morphing commands include options to show partially associated elements, associated nodes, and orphan nodes. Orphan nodes are those that are associated to no geometry. It also can show geometry that has no associated nodes. Lastly, on the FEM in the Simulation Navigator, there is an MB3 command called Report Association. These tools should help you identify where your model has partial geometry/mesh association. 

 

Regards,

Mark

 

Mark Lamping

Simulation Product Management

Simulation and Test Solutions

 

Siemens Industry Sector

Siemens Product Lifecycle Management Software Inc.

 

mark.lamping@siemens.com

www.siemens.com/plm

Re: Boundary Conditions are applied to geometry having partial association of nodes and elements

Experimenter
Experimenter

Hi Mark,

Thanks for your answer.

I actually found out the reason for my problem, and I tried to post it, but somehow the server was down.

 

My problem is that my geometry has overlapping identical volumes and sometimes the boundary condition is applied on the unmeshed volume.

 

For some reason, I've been having this issue with overlapping identical volumes for the last couple of months...  I'll try to find out why.

Re: Boundary Conditions are applied to geometry having partial association of nodes and elements

Siemens Phenom Siemens Phenom
Siemens Phenom

Do you use WAVE links in the idealized part? WAVE will create an associative copy of assembly components in the work part. For CAE this is typically going to be in the idealized part. If you're not careful in setting up your model, you can end up with a polygon body from the original assembly component and the associative copy from the WAVE link. 

 

I'll assume that WAVE is the culprit. Unless you have a compelling reason for using WAVE, you may want to consider using Promote instead. Promote also creates associative copies of assembly component bodies. It is limited in what it can do, but it manages the copy and parent such that you will never get duplicate polygon bodies. For most CAE work, Promote is sufficient and easier to deal with.

 

Regards,

Mark

Re: Boundary Conditions are applied to geometry having partial association of nodes and elements

Experimenter
Experimenter

hi

I usually use WAVE because I tend to have problems with boolean operations on Promoted parts.  I still need to figure out why.

 

I noticed that the Hide Original option in the Settings group of the WAVE Geometry Linker is not available on the WAVE button.  The whole "Settings" tab is just not there. I'll just have to hide the original parts manually.

 

I'll run some tests on promoted and wave parts with boolean operations and will let you know as soon as a figure out what the problem is.

 

Thanks for your help! I'm very satisfied with your answer. You don't need to reply further.

 

 

Re: Boundary Conditions are applied to geometry having partial association of nodes and elements

Experimenter
Experimenter

I suspect that my problem is similar to the problem described in PR Number:    6837531

Re: Boundary Conditions are applied to geometry having partial association of nodes and elements

Experimenter
Experimenter

I searched in the GTAC for similar problems (Boolean on promoted volumes)

 

IR Number: 6372773 - resolved by code 

PR Number: 1807965 - resolved by code changes 

PR Number  - 5712993 - with solution I didn't understand

PR #: 5435282 - Workaround proposed
PR #: 1483924 - limitation of NX.
Document ID: 001-0568954 - Solution in Unigraphics V12 Modeling User Manual, PP 9-47 through 9-52. Where do I find this manual?
 
I do realize that these calls are quite old and would assume the problems were taken cared of.
I couldn't recreate my problem with a simple example, but I'll send it to you as soon as I run into it again.