Rotations bug. 360º

1

I have found a weird bug in the solver just by accident.
The following strip rolls without issue when I request a time step that don’t generate a rotation that pass exactly through the 360º value.
The rotation boundary condition is built as 360 * t by means of an amplitude.
My advancing step is direct to force passing through multiples of 360º if I want.
Overall time periods of 1, 2 or 3 makes the convergence to fail while .98, 1.98 or 2.98 converges without issue.
I would say ccx doesn’t like the 360º value.(180º might have the same issue).
Inp atached

RollingStrip

** Generated by Mecway 24
*NODE
1,12,-0.5,0
2,0,-0.5,0
3,0.75,-0.5,0
4,1.5,-0.5,0
5,2.25,-0.5,0
6,3,-0.5,0
7,3.75,-0.5,0
8,4.5,-0.5,0
9,5.25,-0.5,0
10,6,-0.5,0
11,6.75,-0.5,0
12,7.5,-0.5,0
13,8.25,-0.5,0
14,9,-0.5,0
15,9.75,-0.5,0
16,10.5,-0.5,0
17,11.25,-0.5,0
18,11.25,0.5,0
19,12,0.5,0
20,0,0.5,0
21,0.75,0.5,0
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23,2.25,0.5,0
24,3,0.5,0
25,3.75,0.5,0
26,4.5,0.5,0
27,5.25,0.5,0
28,6,0.5,0
29,6.75,0.5,0
30,7.5,0.5,0
31,8.25,0.5,0
32,9,0.5,0
33,9.75,0.5,0
34,10.5,0.5,0
35,11.625,-0.5,0
36,11.625,0.5,0
37,0.375,-0.5,0
38,0.375,0.5,0
39,1.125,-0.5,0
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41,1.875,-0.5,0
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82,4.6875,0.5,0
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91,8.4375,-0.5,0
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98,10.6875,0.5,0
99,11.8125,-0.5,0
100,11.8125,0.5,0
101,0.5625,-0.5,0
102,0.5625,0.5,0
103,1.3125,-0.5,0
104,1.3125,0.5,0
105,2.0625,-0.5,0
106,2.0625,0.5,0
107,2.8125,-0.5,0
108,2.8125,0.5,0
109,3.5625,-0.5,0
110,3.5625,0.5,0
111,4.3125,-0.5,0
112,4.3125,0.5,0
113,5.0625,-0.5,0
114,5.0625,0.5,0
115,5.8125,-0.5,0
116,5.8125,0.5,0
117,6.5625,-0.5,0
118,6.5625,0.5,0
119,7.3125,-0.5,0
120,7.3125,0.5,0
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124,8.8125,0.5,0
125,9.5625,-0.5,0
126,9.5625,0.5,0
127,10.3125,-0.5,0
128,10.3125,0.5,0
129,11.0625,-0.5,0
130,11.0625,0.5,0
*ELEMENT,TYPE=S4R
1,67,17,18,68
2,69,2,20,70
3,71,3,21,72
4,73,4,22,74
5,75,5,23,76
6,77,6,24,78
7,79,7,25,80
8,81,8,26,82
9,83,9,27,84
10,85,10,28,86
11,87,11,29,88
12,89,12,30,90
13,91,13,31,92
14,93,14,32,94
15,95,15,33,96
16,97,16,34,98
18,99,35,36,100
19,101,37,38,102
20,103,39,40,104
21,105,41,42,106
22,107,43,44,108
23,109,45,46,110
24,111,47,48,112
25,113,49,50,114
26,115,51,52,116
27,117,53,54,118
28,119,55,56,120
29,121,57,58,122
30,123,59,60,124
31,125,61,62,126
32,127,63,64,128
33,129,65,66,130
34,35,67,68,36
35,37,69,70,38
36,39,71,72,40
37,41,73,74,42
38,43,75,76,44
39,45,77,78,46
40,47,79,80,48
41,49,81,82,50
42,51,83,84,52
43,53,85,86,54
44,55,87,88,56
45,57,89,90,58
46,59,91,92,60
47,61,93,94,62
48,63,95,96,64
49,65,97,98,66
50,1,99,100,19
51,3,101,102,21
52,4,103,104,22
53,5,105,106,23
54,6,107,108,24
55,7,109,110,25
56,8,111,112,26
57,9,113,114,27
58,10,115,116,28
59,11,117,118,29
60,12,119,120,30
61,13,121,122,31
62,14,123,124,32
63,15,125,126,33
64,16,127,128,34
65,17,129,130,18
*ELEMENT,TYPE=B31
17,1,19
*ELSET,ELSET=Default
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
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
65
*ELSET,ELSET=Component
17
*SURFACE,NAME=S1
2,S4
*MATERIAL,NAME=Steel
*ELASTIC,TYPE=ISOTROPIC
1200000,0
*DENSITY
7850
*MATERIAL,NAME=Material
*ELASTIC,TYPE=ISOTROPIC
200000000000,0
*SHELL SECTION,ELSET=Default,MATERIAL=Steel
0.1
*BEAM SECTION,ELSET=Component,MATERIAL=Material,SECTION=RECT
0.2,0.2
-1,0,0
*BOUNDARY
1,2,,0
2,1,,0
2,2,,0
2,3,,0
2,4,,0
2,5,,0
2,6,,0
3,2,,0
13,2,,0
17,2,,0
18,2,,0
19,2,,0
20,1,,0
20,2,,0
20,3,,0
20,4,,0
20,5,,0
20,6,,0
21,2,,0
31,2,,0
49,2,,0
50,2,,0
63,2,,0
64,2,,0
105,2,,0
106,2,,0
109,2,,0
110,2,,0
117,2,,0
118,2,,0
*AMPLITUDE,NAME=A_1
0,0
3,-18.84955592154
*EQUATION
2
1,3,1000,19,3,-1000
*STEP,NLGEOM=YES,INC=300,AMPLITUDE=STEP
*STATIC,SOLVER=PARDISO
0.01,3,0,0
*BOUNDARY,AMPLITUDE=A_1
1,5,,1
*BOUNDARY,AMPLITUDE=A_1
19,5,,1
*NODE FILE,GLOBAL=YES
U,RF
*EL FILE
S,NOE
*SECTION PRINT,SURFACE=S1,NAME=Reaction_forces
SOF,SOM
*END STEP
2

Might be good to report on GitHub. This .inp file runs correctly (converges) in Abaqus.

3

Done. :+1:.
I have also confirm some issues with 180º too.

4

it’s not comparable between S4R of Abaqus and CalculiX. It seems a limitation of shell element in CalculiX due to expanded internally to solid, using solid element by meshed properly can solve for similar cases i.e 0deg to 360deg rotations.

anim0

5

How far did you bend “using solid element by meshed properly” ?
What’s the Mmax value?

What’s exactly the limitation? Do you refer to apply multiples of 360º or using moment on the lip to reach large rotations?

6

i’m not yet doing further comparison in force and stress, but all results seems reasonable. Currently, in mesh sensitivity study and seeking the possibility using shell element in CalculiX.

7

I’m not even considering solids. The benchmark is stated for shells. We know there are no issues with solid rotations.

Popular Benchmark Problems for Geometric Nonlinear Analysis of Shells

That’s what requires some scrutiny to find source of issues and keep moving.

8

are that sure? i did investigate further based on this source links, even for 90deg rotation it can not convergences.

Mean Rotation MPC

At 28% of the specified deformation, the incremental time becomes too small and the solution is stopped.

Rigid Body Constraint

At 74% of the specified deformation, the incremental time becomes too small and the solution is stopped.

Coupling/Kinematic

At 78% of the specified deformation, the incremental time becomes too small and the solution is stopped.

9

Investigate.? Don’t make laught.

Then what are you posting?. You don’t even explain what could be the different aproach proposal or compare your results with known values. What’s the aim of that vid.

Regarding S4R not comparable?. Comparison means comparing results, no more no less.
What’s the aim of a comparison or benchmark?. We do use FEM to get results. I don’t give a shit what the formulation is. Do you understand that? You are becoming very anoying man.

If what you feel is the need to always put something on top of others you can do that, I will not waste time responding.

10

are you ANYS in PrePoMax forum and posting similar threads? i’ve been done in given some explanation there about 4 hours ago from now.

don’t want commenting anymore, just ‘wow’ and everyone can judge he/her type of persons.

11

Seems like it fails at lots of angles, 360, 180, less than 90. Maybe the fixed time steps are skipping over the low angles that fail and landing on the higher ones? You get this effect in contact too where you can skip over trouble spots with fixed time steps. All the ways of applying the load - moment, MPC, rotation, rigid body, etc. use MPCs so they’re probably all a bit dicey with shells. I kind of wonder why that is. It seems like they’re so close to working and just pass through a few singularities or something. Seems a pity that the capability is limited by what seems like an unnecessary problem.

I guess you could make a special structure at the tip and apply two pressure loads to form a moment but that’s sort of avoiding the problem and doesn’t generalize very well.