Traction + Cylindrical Coordinate system

Bug Reports
1

Hi Matej,

When a traction is applied to a set of faces in which only some of the nodes are under a Cylindrical coordinate system transformation , Prepomax interrupts and closes.
By other hand, I find the way the cylindrical coordinate system is defined really confusing. From my point of view, user should only be requested to input two point as in the manual.

imagen
imagen612Ă—545 53.7 KB

*Node
1, 1.00000000E+000, 0.00000000E+000, -1.00000000E+000
2, 1.00000000E+000, 1.00000000E+000, -1.00000000E+000
3, 5.00000000E-001, 1.00000000E+000, -5.00000000E-001
4, 5.00000000E-001, 0.00000000E+000, -5.00000000E-001
5, 1.00000000E+000, 5.00000000E-001, -1.00000000E+000
6, 7.50000000E-001, 1.00000000E+000, -7.50000000E-001
7, 5.00000000E-001, 5.00000000E-001, -5.00000000E-001
8, 7.50000000E-001, 0.00000000E+000, -7.50000000E-001
9, 7.50000000E-001, 5.00000000E-001, -7.50000000E-001
10, 8.12500000E-001, 1.00000000E+000, -8.12500000E-001
11, 8.12500000E-001, 7.50000000E-001, -8.12500000E-001
12, 0.00000000E+000, 0.00000000E+000, 0.00000000E+000
13, 8.12500000E-001, 8.75000000E-001, -8.12500000E-001
14, 8.12500000E-001, 6.25000000E-001, -8.12500000E-001
15, 7.50000000E-001, 2.50000000E-001, -7.50000000E-001
16, 6.25000000E-001, 5.00000000E-001, -6.25000000E-001
17, 5.00000000E-001, 2.50000000E-001, -5.00000000E-001
18, 6.25000000E-001, 0.00000000E+000, -6.25000000E-001
19, 6.25000000E-001, 2.50000000E-001, -6.25000000E-001
20, 1.00000000E+000, 2.50000000E-001, -1.00000000E+000
21, 8.75000000E-001, 5.00000000E-001, -8.75000000E-001
22, 8.75000000E-001, 0.00000000E+000, -8.75000000E-001
23, 8.75000000E-001, 2.50000000E-001, -8.75000000E-001
24, 1.00000000E+000, 7.50000000E-001, -1.00000000E+000
25, 8.75000000E-001, 1.00000000E+000, -8.75000000E-001
26, 7.50000000E-001, 7.50000000E-001, -7.50000000E-001
27, 8.75000000E-001, 7.50000000E-001, -8.75000000E-001
28, 6.25000000E-001, 1.00000000E+000, -6.25000000E-001
29, 5.00000000E-001, 7.50000000E-001, -5.00000000E-001
30, 6.25000000E-001, 7.50000000E-001, -6.25000000E-001
31, 7.50000000E-001, 6.25000000E-001, -7.50000000E-001
32, 6.87500000E-001, 7.50000000E-001, -6.87500000E-001
33, 6.25000000E-001, 6.25000000E-001, -6.25000000E-001
34, 6.87500000E-001, 5.00000000E-001, -6.87500000E-001
35, 6.87500000E-001, 6.25000000E-001, -6.87500000E-001
36, 7.50000000E-001, 8.75000000E-001, -7.50000000E-001
37, 6.87500000E-001, 1.00000000E+000, -6.87500000E-001
38, 6.25000000E-001, 8.75000000E-001, -6.25000000E-001
39, 6.87500000E-001, 8.75000000E-001, -6.87500000E-001
40, 5.62500000E-001, 1.00000000E+000, -5.62500000E-001
41, 5.00000000E-001, 8.75000000E-001, -5.00000000E-001
42, 5.62500000E-001, 7.50000000E-001, -5.62500000E-001
43, 5.62500000E-001, 8.75000000E-001, -5.62500000E-001
44, 5.00000000E-001, 6.25000000E-001, -5.00000000E-001
45, 5.62500000E-001, 5.00000000E-001, -5.62500000E-001
46, 5.62500000E-001, 6.25000000E-001, -5.62500000E-001
47, 7.50000000E-001, 1.25000000E-001, -7.50000000E-001
48, 6.87500000E-001, 2.50000000E-001, -6.87500000E-001
49, 6.25000000E-001, 1.25000000E-001, -6.25000000E-001
50, 6.87500000E-001, 0.00000000E+000, -6.87500000E-001
51, 6.87500000E-001, 1.25000000E-001, -6.87500000E-001
52, 7.50000000E-001, 3.75000000E-001, -7.50000000E-001
53, 6.25000000E-001, 3.75000000E-001, -6.25000000E-001
54, 6.87500000E-001, 3.75000000E-001, -6.87500000E-001
55, 5.00000000E-001, 3.75000000E-001, -5.00000000E-001
56, 5.62500000E-001, 2.50000000E-001, -5.62500000E-001
57, 5.62500000E-001, 3.75000000E-001, -5.62500000E-001
58, 5.00000000E-001, 1.25000000E-001, -5.00000000E-001
59, 5.62500000E-001, 0.00000000E+000, -5.62500000E-001
60, 5.62500000E-001, 1.25000000E-001, -5.62500000E-001
61, 1.00000000E+000, 1.25000000E-001, -1.00000000E+000
62, 9.37500000E-001, 2.50000000E-001, -9.37500000E-001
63, 8.75000000E-001, 1.25000000E-001, -8.75000000E-001
64, 9.37500000E-001, 0.00000000E+000, -9.37500000E-001
65, 9.37500000E-001, 1.25000000E-001, -9.37500000E-001
66, 1.00000000E+000, 3.75000000E-001, -1.00000000E+000
67, 9.37500000E-001, 5.00000000E-001, -9.37500000E-001
68, 8.75000000E-001, 3.75000000E-001, -8.75000000E-001
69, 9.37500000E-001, 3.75000000E-001, -9.37500000E-001
70, 8.12500000E-001, 5.00000000E-001, -8.12500000E-001
71, 8.12500000E-001, 2.50000000E-001, -8.12500000E-001
72, 8.12500000E-001, 3.75000000E-001, -8.12500000E-001
73, 8.12500000E-001, 0.00000000E+000, -8.12500000E-001
74, 8.12500000E-001, 1.25000000E-001, -8.12500000E-001
75, 1.00000000E+000, 6.25000000E-001, -1.00000000E+000
76, 9.37500000E-001, 7.50000000E-001, -9.37500000E-001
77, 8.75000000E-001, 6.25000000E-001, -8.75000000E-001
78, 9.37500000E-001, 6.25000000E-001, -9.37500000E-001
79, 1.00000000E+000, 8.75000000E-001, -1.00000000E+000
80, 9.37500000E-001, 1.00000000E+000, -9.37500000E-001
81, 8.75000000E-001, 8.75000000E-001, -8.75000000E-001
82, 9.37500000E-001, 8.75000000E-001, -9.37500000E-001
**
** Elements ++++++++++++++++++++++++++++++++++++++++++++++++
**
*Element, Type=S4, Elset=Shell_part-1
1, 5, 75, 78, 67
2, 75, 24, 76, 78
3, 78, 76, 27, 77
4, 67, 78, 77, 21
5, 74, 71, 15, 47
6, 73, 74, 47, 8
7, 24, 79, 82, 76
8, 79, 2, 80, 82
9, 82, 80, 25, 81
10, 76, 82, 81, 27
11, 27, 81, 13, 11
12, 81, 25, 10, 13
13, 13, 10, 6, 36
14, 11, 13, 36, 26
15, 21, 77, 14, 70
16, 77, 27, 11, 14
17, 14, 11, 26, 31
18, 70, 14, 31, 9
19, 9, 31, 35, 34
20, 31, 26, 32, 35
21, 35, 32, 30, 33
22, 34, 35, 33, 16
23, 26, 36, 39, 32
24, 36, 6, 37, 39
25, 39, 37, 28, 38
26, 32, 39, 38, 30
27, 30, 38, 43, 42
28, 38, 28, 40, 43
29, 43, 40, 3, 41
30, 42, 43, 41, 29
31, 16, 33, 46, 45
32, 33, 30, 42, 46
33, 46, 42, 29, 44
34, 45, 46, 44, 7
35, 8, 47, 51, 50
36, 47, 15, 48, 51
37, 51, 48, 19, 49
38, 50, 51, 49, 18
39, 15, 52, 54, 48
40, 52, 9, 34, 54
41, 54, 34, 16, 53
42, 48, 54, 53, 19
43, 19, 53, 57, 56
44, 53, 16, 45, 57
45, 57, 45, 7, 55
46, 56, 57, 55, 17
47, 18, 49, 60, 59
48, 49, 19, 56, 60
49, 60, 56, 17, 58
50, 59, 60, 58, 4
51, 1, 61, 65, 64
52, 61, 20, 62, 65
53, 65, 62, 23, 63
54, 64, 65, 63, 22
55, 20, 66, 69, 62
56, 66, 5, 67, 69
57, 69, 67, 21, 68
58, 62, 69, 68, 23
59, 23, 68, 72, 71
60, 68, 21, 70, 72
61, 72, 70, 9, 52
62, 71, 72, 52, 15
63, 22, 63, 74, 73
64, 63, 23, 71, 74
**
** Node sets +++++++++++++++++++++++++++++++++++++++++++++++
**
*Nset, Nset=Cilindrical
1, 2, 5, 20, 24, 61, 66, 75, 79
*Nset, Nset=Internal-1_Surface-1
3, 4, 7, 17, 29, 41, 44, 55, 58
*Nset, Nset=Internal-1_Mixed
1, 2, 5, 20, 24, 61, 62, 64, 65, 66, 67, 69, 75, 76, 78, 79, 
80, 82
**
** Element sets ++++++++++++++++++++++++++++++++++++++++++++
**
*Elset, Elset=Internal_Selection-1_Shell_Section-1
1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 
17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 
33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 
49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64
*Elset, Elset=Internal-1_Surface-1_S5
29, 30, 33, 34, 45, 46, 49, 50
*Elset, Elset=Element_Set-1
1, 2, 7, 8, 51, 52, 55, 56
*Elset, Elset=Internal-1_Mixed_S2
1, 2, 7, 8, 51, 52, 55, 56
**
** Surfaces ++++++++++++++++++++++++++++++++++++++++++++++++
**
*Surface, Name=Surface-1, Type=Element
Internal-1_Surface-1_S5, S5
*Surface, Name=Mixed, Type=Element
Internal-1_Mixed_S2, S2
**
** Physical constants ++++++++++++++++++++++++++++++++++++++
**
**
** Coordinate systems ++++++++++++++++++++++++++++++++++++++
**
*Transform, Nset=Internal-1_Mixed, Type=C
0.25, 0, -0.25, 0.25, 1, -0.25
**
** Materials +++++++++++++++++++++++++++++++++++++++++++++++
**
*Material, Name=S235
*Density
7.8E-09
*Elastic
210000, 0.28
*Expansion, Zero=20
1.1E-05
*Conductivity
14
*Specific heat
440000000
**
** Sections ++++++++++++++++++++++++++++++++++++++++++++++++
**
*Shell section, Elset=Internal_Selection-1_Shell_Section-1, Material=S235, Offset=0
0.1
**
** Pre-tension sections ++++++++++++++++++++++++++++++++++++
**
**
** Constraints +++++++++++++++++++++++++++++++++++++++++++++
**
**
** Surface interactions ++++++++++++++++++++++++++++++++++++
**
**
** Contact pairs +++++++++++++++++++++++++++++++++++++++++++
**
**
** Amplitudes ++++++++++++++++++++++++++++++++++++++++++++++
**
**
** Initial conditions ++++++++++++++++++++++++++++++++++++++
**
**
** Steps +++++++++++++++++++++++++++++++++++++++++++++++++++
**
**
** Step-1 ++++++++++++++++++++++++++++++++++++++++++++++++++
**
*Step
*Static, Solver=Pardiso
**
** Controls ++++++++++++++++++++++++++++++++++++++++++++++++
**
**
** Output frequency ++++++++++++++++++++++++++++++++++++++++
**
*Output, Frequency=1
**
** Boundary conditions +++++++++++++++++++++++++++++++++++++
**
*Boundary, op=New
** Name: Fixed-1
*Boundary
Internal-1_Surface-1, 1, 6, 0
**
** Loads +++++++++++++++++++++++++++++++++++++++++++++++++++
**
*Cload, op=New
*Dload, op=New
** Name: Surface_Traction-1
*Cload
5, 1, 6.25
75, 1, 6.25
78, 1, 6.25
67, 1, 6.25
24, 1, 6.25
76, 1, 6.25
79, 1, 6.25
82, 1, 6.25
2, 1, 3.125
80, 1, 3.125
1, 1, 3.125
61, 1, 6.25
65, 1, 6.25
64, 1, 3.125
20, 1, 6.25
62, 1, 6.25
66, 1, 6.25
69, 1, 6.25
**
** Defined fields ++++++++++++++++++++++++++++++++++++++++++
**
**
** History outputs +++++++++++++++++++++++++++++++++++++++++
**
**
** Field outputs +++++++++++++++++++++++++++++++++++++++++++
**
*Node file
RF, U
*El file
S, E, NOE
**
** End step ++++++++++++++++++++++++++++++++++++++++++++++++
**
*End step
2

Please share the .pmx file so that I can test the problem.

The reason for the chosen method with 3 points is that two points do not allow the complete definition of the coordinate system as such but only define the axis Z. The direction of the R and T axes is not defined is the last case and I cannot draw the coordinate system symbol based on two points.

3

I can’t share pmx files sorry.

I will try to explain what I mean with some images.
All nodes in this model share a unique and common Cylindrical coordinate system. It’s axis is passing through the center of this collection of plates.
I have applied a common traction to the edges in direction 1 (Radial). Response is correct, all forces and their arrows point in radial direction but R and T arrows in the symbol doesn’t have any meaning.
They are only representatives for the grey plate.
There is no such an R or T correct axis for cylindrical transformations, then, why asking the user extra data to build it.

Origin point a
z Arrow from a to b
What ever two othonormal axis for R and T to complete the base

screenshot.55
screenshot.551402Ă—763 109 KB

imagen
imagen1086Ă—758 129 KB

screenshot.49
screenshot.49923Ă—614 110 KB

4

Can you create a simple model where this problem occurs and can be shared?

5

This morning, I opened the file I was working to try to reproduce the crash problem and the loads described in my previous post are not there.?Âż?. BC are ok (They are all homogeneous BC).

I know for sure I did save the model before closing because my last solution is still there. There are no “Remove Load” or “Erase Load” at the history. Just an Edit.
Last I did was to create a second Cylindrical coordinate system with the same Z axis but different R and T orientation in the plane to check result was the same.

imagen

Additionally If I press the run button, the model runs, and there is a solution like if there were loads in the model but according to the model tree they aren’t .
I have look in the inp and there are loads.

screenshot.68
screenshot.681238Ă—579 69.4 KB

screenshot.69
screenshot.691480Ă—772 138 KB

6

Hmm, I would need the file to try to reproduce the problem. I have no idea why the loads would go missing. Or the loads are not shown in the tree since they seem to exist in the .inp file.

What happens if you regenerate the model?

7

But in your input file, all the nodes with surface traction are transformed, right ? After all, transformation in PrePoMax is applied per BC/load so all nodes selected for it will be transformed when a coordinate system is assigned.

Here’s a model recreated from this input deck:

Cyl test.pmx (127.9 KB)

8

If I regenerate, loads show up again in the tree.
Although there is an exception in the Regeneration process analisys end up fine and show the same results"

imagen
imagen1505Ă—603 110 KB

Exception during the regeneration process:

07/10/24 11:51:46
07/10/24 11:51:46 **** Exceptions ****
07/10/24 11:51:46 Add result coordinate system: Object reference not set to an instance of an object.

9

Thanks for looking at this.
The bug report has evolved in some way. I’m trying to reproduce again / recover the initial reported crash.

The question still remains. What happens if I apply a surface traction to a surface in which only some of the nodes are transformed?
Is the traction applied in the global coordinate system, the Transformed coordinate system or transformed nodes transformed and the rest in global coordinates.?
That’s what I was testing when it suddenly crashed.

EDITED: Think in your last Spherical shell Buckling problem. Imagine I have impose the BC using a local cylindrical coordinate system. If I later apply a Traction to all the Dome surface in the vertical direction,… how is that traction applied into the nodes with Cylindrical BC.?

10

Internally, transformation is defined independently of BCs and loads - it’s just done for a set of nodes that can be later use for said BCs/loads. Once a node is transformed, all its inputs are in the local CSYS so surface traction (internally applied as *CLOAD) too. But only for the transformed nodes. Of course, if the nodes are fixed by a BC, it won’t matter so much.

From Abaqus documentation:

When a transformed coordinate system is associated with a node, all input data for concentrated forces and moments and for displacement and rotation boundary conditions at the node are given in the local system.

11

If the user inputs a Traction or BC in Coordinate System “Global”, I think the correct procedure should be to Prepomax adjust the direction on those nodes under a *transform to align with the rest of the NodeSet outside the *Transform card.

Same with punctual loads or any other load affected by transform.

12

There is a limitation in CalucliX when using the *Transform keyword. The transform keyword defines a local coordinate system to a set of nodes. The previous transform definition is overridden if another transform card is used on the same nodes. Once a local coordinate system is defined, it cannot be changed.

PrePoMax directly uses the *Transform keyword in BCs and Loads. If a BC is defined for a set of nodes in a local coordinate system, a Transform card is created for these nodes. So, for any other feature using these nodes, it is important to note that the nodes have a local coordinate system defined and connot use the global coordinate system any mode.

I could create my own layer of coordinate systems where BC and load direction would be recomputed before being written to the .inp file. In this way, the coordinate system would be applied only for one feature and would not be defined to a set of nodes. Using the nodes in another feature woud not be affected.

In the end, the decision was to use the built-in functionality of CalucliX.

13

I think this is something only the user can correctly define. To prevent problems like this, I plan to implement a check where such collisions would be found and reported to the user.

14

That may be a solution.

The other problem with the Coordinate System symbol (R and T) is not so urgent because an attentive user is put on alert when the axis and the load arrow do not point in the same direction, but the case we now discuss does not give any warning.
You can think from the arrow that you are loading correctly in the global direction and the load has been silently distributed according the local coordinate system.

I’m questioning now if this hasn’t been the reason why some beams occasional showed displacements and rotations in weird directions.

If I’m not wrong user inputs suitable to be Transformed are:

Traction
Punctual Loads (including moments)
Displacements
Rotations (Pending Don Guido comments)

Pressures doesn’t seem affected. What about Gravity or Centrifugal forces?

15

Only nodal BCs, loads and MPCs are affected. Not distributed loads (*DLOAD). Even initial conditions aren’t affected:

Please note that vector and tensor quantities have to be provided in the GLOBAL (rectangular) coordinate system, no matter whether an *ORIENTATION card or *TRANSFORM card applies to the corresponding element or node, respectively.

1 Like
16

I am more and more convinced that Neil Armstrong’s photo of the footprints on the Moon were Don Guido’s… :rofl:
I mean in the good sense of course. Each time I arrive to somewere it seems he has alrready been there.

screenshot.72

17

May I move this topic to Feature requests since it is not really a bug? I think a feature is missing that will check if a node is used in multiple coordinate systems (global or local) at the same time.