MODELLING GLUE CONNECTION WITH RBE 2 ELEMENTS 1

[Xprivate]

HI Everyone ,

i was modelling the glue connection for a windshield.the thing is i want to run a non linear glue contact analysis. since i dont have a license for that i planned to connect the matching glue contact mesh region with RBE2 elements. what do you think about this approach and how accurate is this approach ?

 

[BlasMolero]

Bad, very bad meshing approach. RBE2 elements should be used as the very last resource.
BASIC NONLINEAR (SOL106) is part of BASIC NASTRAN, then is included in your license.
By the way, Glue effect is not supported in nonlinear analysis (SOL106):

 ^^^USER    FATAL   MESSAGE (IFPS)   
 ^^^FOR SOL 106 OR 129, GLUE CONNECTION STIFFNESS DOES NOT UPDATE FOR LARGE DISPLACEMENT CAPABILITY.   
 ^^^IF THE GLUE CONNECTION IS LOCATED IN SECTIONS THAT HAVE LARGE DEFLECTION, THE COMPUTED CONNECTION FORCES WILL BE IN ERROR. 
 ^^^IF THE GLUE CONNECTION IS LOCATED IN SECTIONS THAT DO NOT HAVE LARGE DEFLECTION, THE CONNECTION FORCES SHOULD BE REASONABLY ACCURATE.    
 ^^^IN THAT CASE, USERS CAN SET NASTRAN SYSTEM(784)=1, AND THIS FATAL TRAP WILL NOT BE ISSUED.

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/

 

[Xprivate]

hi Blas , thank you for your response. But glue is essentially rigid connection, if i model all my connection region with glue elements the behaviour shouldnt change right ?

yes SOL106 doesnot include the effects of glue , so that was the best approach i could think off

 

[BlasMolero]

Hello!,
But RBE2 elements moves like a rigid element, the coordinates are not updated in a nonlinear analysis (SOL106), this is the main limitation with SOL106.
The modern Nastran Multi-Step NonLinear (SOL401) support RBE2 elements for large displacements effect, updating it coordinates during iterative analysis.
In summary, for SOL106 better use any element different to RBE2 rigid elements, you can play with CBAR/CBEAM elements with reasonable cross section.

Glue is a simple and effective method to join meshes which are dissimilar. It correctly transfers displacement and loads resulting in an accurate strain and stress condition at the interface. The grid points on glued edges and surfaces do not need to be coincident. Glue creates stiff springs or a weld like connection to prevent relative motion in all directions.
See my blog, but valid for linear static analysis (SOL101):

https://iberisa.wordpress.com/2011/...-surface-contact-por-jim-bernard-siemens-plm/

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/

 

[Xprivate]

Thanks you Blas for the explaination