SOL601/106 Shell to Solid (RBE2/RBE3)


Hi all,


After some time using SOL101 I am trying learn SOL601 to compare the solutions. I have "large" sliding in my problem and would like to see if there is any significant changes. However, I stumbled accross a problem very early Smiley Happy


I found out the hard way that EDGE-SURFACE glue connection is not supported in SOL601. Took me a while to figure this out. I just assumed that this was supported as it is with SOL101. A very easy and convenient method to connect SHELL and SOLID together. My model is HUGE! (750k nodes) with mainly SHELL (8-quad) and 20-HEX in critical areas/ where SHELL is not usable. my assembly FEM I thought to myself that using 1D connection (EDGE-FACE) will "connect" my SHELL and SOLID mesh/geometry together to eliminate rigid body errors. Well...looks like that did not work. I get following error message:

     ***ALERT: The x-rotation at node 2534 is inadmissible
               as an independent (master) degree of freedom in a constraint equation
               since it is a slave degree of freedom in another constraint equation or rigidlink


The f06 file is full of this "ALERT" message!


I put my money on that this is something to do with the 1D connection elements. When I use the EDGE-FACE in AFEM I get both RBE2 and RBE3 elements. I have to admit that I do not fully understand RBE2/RBE3 elements yet...but for now I just want to connect SHELL and SOLID together and see if that will help my analysis to converge Smiley Happy









Re: SOL601/106 Shell to Solid (RBE2/RBE3)

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Solution Partner Phenom

Dear Thomas,

In fact, GLUE EDGE-TO-FACE with NX NASTRAN is a great feature, I use a lot as well. For SOL601 you can use the traditional method of embedding one shell element between the solid faces and merge nodes (do this far from areas where you want to obtain accurate results), this is a "trick" that allow you to transfer (between "incompatible" elements) not only displacements but also rotations:


Of course, you can use RBE2 elements, but the general consequence is to have locally strong stress concentrations.

Best regards,

Blas Molero Hidalgo, Ingeniero Industrial, Director
Blog Femap-NX Nastran:

Re: SOL601/106 Shell to Solid (RBE2/RBE3)




Thanks for your reply. So I understand there are two possible approaches to connect SHELL-SOLID in SOL601. I will probably try both to learn and compare, but I hope EDGE-SURFACE glue will be available one day in the future for SOL601Smiley Happy


1. Merge nodes Shell and solid


I assume this requires two solid elements through thickness. Something tells me that merging the midnodes should be avoided.


2. RBE2


From top of my head this looks like the fastest approach to connect shell to solid. I tried to use 1D connection elements using EDGE-FACE but perhaps I should used NODE-NODE? With NODE-NODE I can choose only RBE2. EDGE-FACE gave me both RBE2 and RBE3.