*Equation and remove in beam element models

1

hi,

reading of documentation, there’s an option to remove in specific nodes by *Equation. However, the behavior of the solver shown unexpected, it seems nodes and dof’s been defined are in expanded ones. This problem does not occur when node is separated and connecting by *Equation.

is this problem such as bug or currently limitation? hopefully, fix or improvement is available in the next or future versions of CalculiX.

regards,

2023-12-07 19_36_26-errB32Rbalok.inp - SciTE
2023-12-07 19_36_26-errB32Rbalok.inp - SciTE1280×656 40.5 KB

below similar problem using separated nodes.

**
** Structure: beam fixed both end, two element, hinged at spans
** Test objective: B32R elements.
**
*NODE,NSET=Nall
1, 0, 0, 0
2, 0, 0, 25
3, 0, 0, 50
4, 0, 0, 75
5, 0, 0, 100
6, 0, 0, 50
*ELEMENT,TYPE=B32R,ELSET=EAll
1,1,2,6
2,3,4,5
*BOUNDARY
1,1,6
5,1,6
*MATERIAL,NAME=ALUM
*ELASTIC
1E7,.3
*DENSITY
2.7E-9
*BEAM SECTION,ELSET=EAll,MATERIAL=ALUM,SECTION=RECT
5.,10.
1.d0,0.d0,0.d0
*Equation
2
6, 1, 1, 3, 1, -1
2
6, 2, 1, 3, 2, -1
2
6, 3, 1, 3, 3, -1
*STEP
*STATIC,SOLVER=SPOOLES
*DLOAD
Eall,GRAV,9810.,0.,-1.,0.
*El File,Output=3D
S,E
*Node File
U
*End Step

2023-12-07 19_42_44-CalculiX GraphiX
2023-12-07 19_42_44-CalculiX GraphiX723×636 23 KB

2023-12-07 19_43_58-CalculiX GraphiX
2023-12-07 19_43_58-CalculiX GraphiX723×636 23.8 KB

2

@xyont , My understanding of the manual goes in a different way, I read that the option *equation remove can only be applied to nodes that already have been defined by *equation.
This is also the way *equation remove have been used in the test examples:
equrem1, equrem2, equrem3.
I’m not sure that I would consider it as a limitation, for me it’s more some additional input in the data file.

1 Like
3

thanks @fgr for reminder, although still not clear for me since the document also notified it can remove linear equation were generated internally. Unfortunately, the same keyword is working in a different way.

*edited
it seems to be right, i miss to interpreted above sentences. It’s a specific to Remove All options. This is not a bug or limitation, and removing some dof’s at specific node in continuous mesh is not possible. Only can do by separated nodes and connecting with MPC as in my previous example.

2 Likes
4

@xyont , I’ll admit after had read the manual a couple of times more and doing a few tests by myself that I don’t either understand the last sentence in “*Equation, Remove All”:

or whether they were generated internally.

It would be nice to see a working data input with that option on nodes which haven’t previously been defined in the in earlier step with *equation.