Implementation of orbital movement (no rotation)

[SiZeMaSi]

Hey guys,

I currently have some problems figuring out how to implement the movement of a rectangular part/surface along a circular path.
I cannot imagine to prescribe the motion with the conventional displacement/rotation- BCs, since the coordinates in the x-y- plane for instance would change all the time.
Does someone have any ideas or experience with this?

Tanks in advance!

 

[akabarten]

Hi,

I never did such trick, but I would try boundary condition with local cylindrical coordinate system.
I expect then you can apply boundary condition with radial direction to introduce rotation for your part.

For details check Abaqus documentation:
- Abaqus Analysis User's Manual, 2.1.5 Transformed coordinate systems
- Abaqus Analysis User's Manual, 33.3.1 Boundary conditions in Abaqus/Standard and Abaqus/Explicit

Regards,
Bartosz

 

[SiZeMaSi]

Thanks for your response.
I must say that I am not really sure that I understand what you mean. It must be clear, that the part should move on an orbital path, while the part should not rotate around its own axis.
I attached a simple sketch that shall explain this a little bit better.

Thanks!

 

[IRstuff]

Part of the difficulty seems to be your perception of the problem. There is no rotation of anything. The object is merely being laterally displaced over time, where dx = omega*radius*cos(omega*t)*dt and dy = omega*radius*sin(omega*t)*dt

TTFN
faq731-376

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[akabarten]

Hi,

I did not get you question right.
Thanks for the picture, now I understand what movement you want to get.

I fully agree with IRstuff, to describe such movement you need to use uniform circular motion equations.

The simplest way is to create amplitude to describe position with x and y axis over the time with Excel or similar software.

You can also use the equations directly with Abaqus.
You can define user amplitude and code the equations with FORTRAN subroutine (UAMP/VUAMP) to describe your movement.
I am attaching simple model with VUAMP subroutine for Abaqus/Explicit as an example.

Regards,
Bartosz

 

[SiZeMaSi]

thanks for all your help.
unfortunately, I have no fortran-compiler @ work...
I introduced the movement by implementing several rigid wires, turning them and connecting their movement to my assembly by making Tie-constraints.
It may not be the most elegant way, but it seems to work for now.
The discussion with you guys made me figuring thi way out. Thank your for that!