Dynamic simulation of Geneva mechanism

[iescelanova]

Hi everybody,

I'm starting to learn how to use the dynamic enviroment of Inventor.

I want to simulate a Geneva mechanism (I get it from a book of Randy H). I'm using a 3D contact between the wheel and the drive, but it is not working properly.

The Geneva wheel oscillates a lot a there is a lot of interference with the mechanism.

I have checked it in the assembley enviroment and works perfectily (set of contacts).Probably I am misunderstanding something.

Could anybody check it and say me what I am doing wrong?

Best regards,

Celso

[TheCADWhisperer]

Can you Attach zip rather than rar?

[iescelanova]

Thank you for your answer.

I attach the zip file.

[TheCADWhisperer]

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@iescelanovawrote:

... (I get it from a book of Randy H). 

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In Geneva-Driver Sketch2 and 3 are not fully constrained?

The part is not modeled correctly and I doubt it follows the dimensions in the book.

The assembly most certainly does not work correctly in the Assembly Environment.

(You can drag the Geneva-Wheel to see incorrect movement.)

Geneva-Wheel is missing dimensions and constraints?

I am pretty sure the book covers these topics.

Sketch1 in Geneva-Base is not fully defined?

[iescelanova]

Hi CadWhisperer,

Hi CadWhisperer,

As you could check, the Geneva wheel is not fully constrained. This is because is imported from Autocad (is a exercise of the book), although the dimensions are correct.

I think that in the assembly enviroment, the mechanism works correctly. I attach a video showing how it works. Could you say me why in your opinion is working bad?

I have not fully constraited all the parts, because I was only playing with the dynamic enviroment, trying to understand how the 3d contact works.

Best regards,

Celso

[TheCADWhisperer]

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@iescelanovawrote:

I think that in the assembly environment, the mechanism works correctly. I attach a video showing how it works. Could you say me why in your opinion is working bad? 

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1. Your parts do not match the book.

2. Try dragging the Geneva-Wheel.  What do you observe.

If the parts were modeled correctly - the mechanism motion will not fail.

[johnsonshiue]

Hi! I agree with @TheCADWhisperer. The Geneva-Wheel.ipt is the main problem. The sketch are all under-constrained. Although the shape looks fine, there are geometric imperfection due to under-constrained geometry. I bet you created the sketch in AutoCAD or other programs and then copy and paste back to Inventor. The part can be modeled more easily. You can simply model one key and then pattern 6 occurrences. There is no need to create the complicated sketch.

Many thanks!

[WHolzwarth · Accepted solution]

I didn't look at unconstrained sketches. But I could get DS running with 2 changes:

- Velocity for Revolution:2 only -180 deg/s

- Damping for Revolution:1 2 N mm s/deg for Min and Max

2018 IAM attached, all other files are unchanged.

[iescelanova]

That's it !!!. It works fine now.
I appreciate it.
Regards,
Celso