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BCHANGE in SOL103?

Benny Hill
Sometimes it might be useful to have more control about glued areas between two bcbodies in SOL103. In SOL101 and SOL400 I can use BCHANGE to achieve this but this option is not available in SOL103. My current workaround for SOL103 is to define additional bcbodies only containing the elements which should be glued. This is a lot of work and often leads to the following warnings in the f06 file because two bodies share the same nodes:
 
"warning: node    11764 belongs to bodies  28  33. for the contact algorithm it will belong to body   33 only."
 
Will the BCHANGE option or something similar become available for SOL103 in future releases of Nastran? Is there a smarter way to gain more control about glued regions in SOL103? Thanks for any suggestion!
 
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    SOL 103 is linear and Glue contact is only option supported for contact bodies. Touching contact in SOL103 is not a option or more pointedly not meaningful. So generally use of BCHANGE in sol 103 in not necessarily warranted and there is no real performance benefits to be had with BCHANGE it, as time needed for contact boundary calculation will be much less then time required for eigen solver. In light of this it is unlikely that it will be considered for future impelmentation and especially it makes more sense in the nonlinear context.
     
    Thanks,
    Sanjay.
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    Hello Sanjay, thanks for your answer. My intention is not to use touching contact in SOL103. I am only looking for a way how I can control which areas between two bodies should be glued and which should not be glued (check attached picture). Thanks to the boundary search Nastran will glue all four faces of the bodies but I want only two of the four faces to be glued. How can I achieve this in Nastran without defining a additional body?
    Glue_SOL103
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    I see your point and agree.
     
    In the end Nastran has to know which faces to glue. The general approach will find matching faces and all 4 faces. To limit it to just two matching faces contact faces must be selected as you have done. When you define the BCHANGE one still has to define FACES to exclude. I suppose there is timesavings to be had during modeling assuming the faces being excluded are fewer. From Computational time perspective timesaving would be minimal.
     
    I assume what you are looking for a feature in Nastran is to have the contact algorithm work in connection with ALLBODY option to exclude certain areas in sol103. I could open an enhancement request for this if one does not exist for linear solution where GLUED option is supported. If others on the forum can chime with their though it would be good.
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    I have to say that I really like the Nastran approach to search for matching faces between bodies because it saves time when you have to deal with big assemblies with many components. But in some situations the algorithm overshoots and glues areas which you don't want to be glued. For those "tricky" areas in your assembly it would be great to have the possibility to change the boundary of the BCBODY to include or exclude certain areas.
     
    As written in my first post this functionality is already available in SOL101 and SOL400 via the BCHANGE entry. For me it would be a great feature to see the BCHANGE entry available in SOL103 (and other dynamic solution sequences like SOL111, SOL112 ...) for the initial contact step in which the bodies are glued together. If it is possible to open a enhancement request I would appreciate this.
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