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Linear buckling solution with contacts

Hello all,

 

I meet some problem, I have to check some kind of the structure where flanged connections are used.

I prepared some shell model with contacts, flanged connections (bolts) are pre-stressed by applying a temperature in order to obtain proper stiffness of the connection. In linear static solution everything is fine. Stress are in desired range and displacements are accetpable.

Now is the harder part, in order to check the safety factor against buckling I run the SOL105. Exactly the same loads and constraints are uese but the results (buckling loads) differ a lot from the linear solution performed before. Global displacement in SOL101:16mm, SOL105: 96mm.

I Found out that in the SOL 101 I had to set proper contact parameters in order to obtain good results but in the SOL105 there is no such option available. In the analysis information I found such message, but I do not know how to interpret it:

 

WARNING
There are surface-to-surface contact simulation objects used in a SOL 105 (linear 
buckling) solution.
The accuracy of the buckling load will often depend on the size of contact area solved in 
the static preload solution. In that case the load defined for the preload analysis 
should be similar in magnitude to the computed buckling load. It is recommended to 
manually update the defined preload to match the buckling load so that they are within 
10% in magnitude.

Do anyone know how to apply above recommendation ?

 

Is there option to use directly results from SOL101 in SOL105 ?

 

Thanks Smiley Happy

 

3 REPLIES

Re: Linear buckling solution with contacts

Ok, I managed to obtain the same results for Buckling Load results as for SOL101 by putting additional line to input file for NASTRAN:

 

BCTPARM      100 INIPENE       3

This line was responsible for "calibrating" contacts, however do anyone can explain the warning mentioned before?

 

And question to @SiemensPLM, is it a bug in my version of NX that the "Global Contact Parameters" are not available in SOL105 Solution Options? When I put above line into the NASTRAN input file it works, so why it is not visible by default in Solution options?

 

Re: Linear buckling solution with contacts

Siemens Phenom Siemens Phenom
Siemens Phenom

Perhaps you are using NX 9 or earlier? I checked versions 9, 10, and 11 (in reverse order). 10 and 11 both have the ability to define INIPENE at the solution and contact pair levels. NX 9 provides it at the contact pair level. 

 

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: Linear buckling solution with contacts

That's right. I work on NX9