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Add strip bending example
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@mkraska
mkraska committed Dec 30, 2015
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5 changes: 5 additions & 0 deletions README.md
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Expand Up @@ -36,3 +36,8 @@ The examples usually require CalculiX 2.9, some of them might run with the bConv
width="200"
title="Tensile test, axisymmetric model, expanded in postprocessing, path plot demo">
](Drahtbiegen/Zug/)
[<img
src="Streifen/sh-def.png"
width="200"
title="Bending of an elastic strip, beam, shell and solid models with various rotation constraints">
](Streifen/)
48 changes: 48 additions & 0 deletions Streifen/README.md
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# 90°-Bending of an Elastic Strip

This example demonstrates the application of prescribed rotations to node sets.
The structure is an elastic flat strip of dimensions 100x10x1 mm³. One end is
fixed and one end is rotated by 90°. The strip thus is bent into a quarter
circle. We investigate the following cases:

* Beam model
* Shell model
* Solid model with mean rotation constraint
* Solid model with rigid body constraint.

| File | Contents |
| :------------- | :------------- |
| [b.fbd](b-pre.fbd) | CGX script, beam model |
| [b.inp](b.inp) | CCX input, beam model |
| [sh.fbd](sh-pre.fbd) | CGX script, shell model |
| [sh.inp](sh.inp) | CCX input, shell model |
| [def-plot.fbd](def-plot.fbd)| CGX deformation plot |

# Beam Model
In CGX, b3 elements are specified. This results in B23R elements in the CCX input. These are internally expanded into C3D20R.

The rotation is applied as constraint to dof 5 of the node at the free end of the beam. With the default convergence control settings, only 12% of the specified rotation are reached.
```
> cgx -b b.fbd
```
The script contains the pre-processing, solution and post-processing.

<img src="b-mesh.png" width="300" title="Beam model">
<img src="b-def.png" width="300" title="Residual forces">

<img src="b.png" width="600" title="Convergence plot">

# Shell Model
In CGX, qu8 elements are specified. This results in S8R elements in the CCX input. These are internally expanded into C3D20R.

The rotation is applied as constraint to dof 5 of the nodes at the free end of the strip. The solution converges very well. Due to the large rotations, only invariant stress measures like v. Mises or principal stresses are useful.
```
> cgx -b sh.fbd
```

<img src="sh-mesh.png" width="300" title="Shell model">
<img src="sh-def.png" width="300" title="Residual forces">

<img src="sh.png" width="600" title="Convergence plot">

# Solid Model
282 changes: 282 additions & 0 deletions Streifen/Streifen.sm
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<p>Length </p>
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<p>Bending angle</p>
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<p>Young's modulus</p>
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<p>Poisson's ratio</p>
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<p>radius ofurvature </p>
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<p>long. strain at the surface</p>
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<p>longitudinal stress</p>
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<p>(plane stress, at the edges)</p>
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<p>Moment of inertia</p>
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<p>Bending moment</p>
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29 changes: 29 additions & 0 deletions Streifen/b.fbd
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# Large rotations, small strain
# beam model
pnt p1 0 0 0
seta fix se all
swep all rot tra 100 0 0 20

elty all be3
mesh all
send all abq
send all abq nam

send fix abq spc 123456
send rot abq spc 5 1.57

plot l all
plus n all
plus n fix b
plus n rot t
frame
hcpy png
sys mv hcpy_1.png b-mesh.png

sys ccx b
sys python ../Scripts/monitor.py b&

read b.frd
ds -0 e 4
read def-plot.fbd
sys mv hcpy_2.png b-def.png
21 changes: 21 additions & 0 deletions Streifen/b.inp
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*include,input=all.msh
*boundary
*include,input=fix_123456.bou
** material definition
*material, name=steel
*elastic
210000,0.3,0
*beam section, elset=Eall, material=steel, section=rect
1,10
0,0,1
*STEP, NLGEOM
*STATIC
0.01,1,,0.01
*boundary
*include,input=rot_51.57.bou
*el file
S
*node file
U
*end step

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