Centrifugal Force Simulation

[akeyokey]

Hello I would like to simulate centrifugal force on propeller but I'm new on freeCAD and i don't find in FEM workbench the option so could you please give me some clues.

OS: Windows 10
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.16.6706 (Git)
Build type: Release
Branch: releases/FreeCAD-0-16
Hash: f86a4e411ff7848dea98d7242f43b7774bee8fa0
Python version: 2.7.8
Qt version: 4.8.7
Coin version: 4.0.0a
OCC version: 6.8.0.oce-0.17

[fandaL]

It needs a bit hand work on .inp file which you need to open and modify before running an analysis.
Look here: https://forum.freecadweb.org/viewtopic.php?t=15157

Transform and self weight tools in the latest 0.17 version could help, but do not make all the work.

[Jee-Bee]

use *DLOAD
See http://www.feacluster.com/CalculiX/ccx_ ... de227.html
I have see the term dload somwhere in FEM module but don't know how much is intergrated.

[akeyokey]

Thanks for this clues, i will try it

[JeffWitz]

On Calculix, define the element set to be subjected to the centrifugal loading. The magnitude is calculated as density multiplied by the square of the angular velocity (in radians/second). For axisymmetric problems the axis of rotation must be the global Z-axis, which must be specified as 0.0, 0.0, 0.0, 0.0, 1.0, 0.0.

Following line for centrifugal loading:

Element number or element set label.
CENTRIF
rotational speed square ($ \omega^2$)
Coordinate 1 of a point on the rotation axis
Coordinate 2 of a point on the rotation axis
Coordinate 3 of a point on the rotation axis
Component 1 of the normalized direction of the rotation axis
Component 2 of the normalized direction of the rotation axis
Component 3 of the normalized direction of the rotation axis

Example:

*DLOAD
Eall,CENTRIF,100000.,0.,0.,0.,1.,0.,0.

[kuroshivo]

Hi, just to complete the question, this is my approach (it does not involve FreeCAD, yet):

https://www.youtube.com/watch?v=tM-WBgG3YrA&t=2s

You can try it yourself online at http://www.caeplex.com

[akeyokey]

I have a little question more,

Code: Select all

*DLOAD
Eall,CENTRIF,70225.,0.,0.,17.5,1.,0.,0.

My beam is on the x axis. and my rotation axis is on the z axis. But I don't understand the three last parameters of "dload"?

Code: Select all

1.,0.,0.

This previous code is the normal of z?
If yes, those are also normal of z so how can i choose the correct one?

Code: Select all

1.,1.,0.
0.,1.,0.

OS: Windows 10
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.16.6706 (Git)
Build type: Release
Branch: releases/FreeCAD-0-16
Hash: f86a4e411ff7848dea98d7242f43b7774bee8fa0
Python version: 2.7.8
Qt version: 4.8.7
Coin version: 4.0.0a
OCC version: 6.8.0.oce-0.17

[ulrich1a]

It is really recommended to use a 0.17-developement version of FreeCAD in this case. Centrifugal load is still has not all available, but it is much easier to analyze your case.
I rotated your model by 45° and I increased the hub angle, to cover 90°. Both measures allow a convenient fixture of your model in space by the usage of the displacement constraints. I fixed the top face of the hub in z-direction and the cut-hub-faces in x respective y-direction.
These constraints takes care that the hub can only move in those ways, it will move in reality under load.
You need now only add a gravity-constraint and replace the one discussed line in the input file, to get the analysis.

Code: Select all

*DLOAD
**Eall,GRAV,9810,0.0,0.0,-1.0
Eall,CENTRIF,70225.,0.0,0.0,0.0,0.0,0.0,1.0

Ulrich

OS: Debian GNU/Linux 8.7 (jessie)
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.17.10424 (Git)
Build type: Release
Branch: Rueck6
Hash: 5c5537da737d55e77ecde65fda7d1ea6512ffe76
Python version: 2.7.9
Qt version: 4.8.6
Coin version: 4.0.0a
OCC version: 7.1.0

[akeyokey]

It is really recommended to use a 0.17-developement version of FreeCAD in this case. Centrifugal load is still has not all available, but it is much easier to analyze your case.
I rotated your model by 45° and I increased the hub angle, to cover 90°. Both measures allow a convenient fixture of your model in space by the usage of the displacement constraints. I fixed the top face of the hub in z-direction and the cut-hub-faces in x respective y-direction.
These constraints takes care that the hub can only move in those ways, it will move in reality under load.
You need now only add a gravity-constraint and replace the one discussed line in the input file, to get the analysis.

Code: Select all

*DLOAD
**Eall,GRAV,9810,0.0,0.0,-1.0
Eall,CENTRIF,70225.,0.0,0.0,0.0,0.0,0.0,1.0

Ulrich

OS: Debian GNU/Linux 8.7 (jessie)
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.17.10424 (Git)
Build type: Release
Branch: Rueck6
Hash: 5c5537da737d55e77ecde65fda7d1ea6512ffe76
Python version: 2.7.9
Qt version: 4.8.6
Coin version: 4.0.0a
OCC version: 7.1.0

Thanks you for helping me, first question when i open your files i get this error on freecad 0.17 system : windows 10

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<unknown exception traceback><type 'exceptions.ImportError'>: No module named PyObjects._FemSolverCalculix
<unknown exception traceback><type 'exceptions.ImportError'>: No module named PyObjects._FemMaterial
<unknown exception traceback><type 'exceptions.ImportError'>: No module named PyObjects._FemConstraintSelfWeight
<unknown exception traceback><type 'exceptions.ImportError'>: No module named PyObjects._FemResultMechanical
<unknown exception traceback><type 'exceptions.ImportError'>: No module named PyGui._ViewProviderFemSolverCalculix
<unknown exception traceback><type 'exceptions.ImportError'>: No module named PyGui._ViewProviderFemConstraintSelfWeight
<unknown exception traceback><type 'exceptions.ImportError'>: No module named PyGui._ViewProviderFemMaterial
<unknown exception traceback><type 'exceptions.ImportError'>: No module named PyGui._ViewProviderFemResultMechanical

And i don't understand why you choose :
Component 1 of the normalized direction of the rotation axis 0
Component 2 of the normalized direction of the rotation axis 0
Component 3 of the normalized direction of the rotation axis 1

Code: Select all

Eall,CENTRIF,70225.,0.0,0.0,0.0,0.0,0.0,1.0

OS: Windows 10
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.17.10150 (Git)
Build type: Release
Branch: master
Hash: 978978f7dd1814083d7b9c9fc4267dba25f58a80
Python version: 2.7.8
Qt version: 4.8.7
Coin version: 4.0.0a
OCC version: 7.0.0

[fandaL]

And i don't understand why you choose :
Component 1 of the normalized direction of the rotation axis 0
Component 2 of the normalized direction of the rotation axis 0
Component 3 of the normalized direction of the rotation axis 1

Code: Select all

Eall,CENTRIF,70225.,0.0,0.0,0.0,0.0,0.0,1.0

The last three numbers 0.0, 0.0, 1.0 are not a normal vector. It is "normalized" axis vector, which means that it is a vector in direction of the rotation axis with length equal to 1.
In this case the rotation axis is in Z direction.