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Centrifugal force applied to a pendulum in dynamic simulation

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Message 1 of 15
maaduk
1911 Views, 14 Replies

Centrifugal force applied to a pendulum in dynamic simulation

Hi guys, i am new here on the forum, but not new with Inventor. Version i work with is 2011. I want to make Inventor calculate for me the force by which the pendulum acts towards the die ring, which is grounded. In my simulation, i defined material properties of all the parts, gravity, motion around vertical axis is set to constant value. It turns nicely. But, i can not set the die ring to be the position limiting factor to my pendulum and i can not make centrifugal force created by rotation to act on the pendulum. I attach picture of model, which i created to test if this works.  Thanks a lot if someone come up with something.

madduk

14 REPLIES 14
Message 2 of 15
JDMather
in reply to: maaduk

What book are you using to learn Dynamic Simulation?

Can you attach your assembly here?


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Message 3 of 15
maaduk
in reply to: JDMather

Hi and thank you for the answer. I do have "Up and Running with Autodesk Inventor Simulation 2011" and "Mastering Autodesk Inventor 2010". I attach the assy here.

 

Message 4 of 15
JDMather
in reply to: maaduk

I don't think either of those books cover Dynamic Simulation (in any detail), I was thinking more of Wasim Younis book http://www.amazon.com

 


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Message 5 of 15
maaduk
in reply to: JDMather

It is his book. See attached

Message 6 of 15
JDMather
in reply to: maaduk

Yes, but I'm not sure your problem is covered in the book.

I haven't had chance to experiment with your problem.

If you don't have money to purchase the book or if this is your only real need (to solve this particular problem) you might wait a couple of days and see if someone posts a solution (Fridays are usually slow).


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Message 7 of 15
maaduk
in reply to: JDMather

It is not a problem to buy some book, if i know there is an sollution in there. I will look if i can find some other book related to this topic. I am still working on that one and won't stop till i get it right. Will use that more than once.Thanks for answer. 

Message 8 of 15
henderh
in reply to: maaduk

Hi Madduk,

 

  There are a couple different ways to go about it.  The easiest way is to disable the zero deg/s^2 acceleration imposed motion in Revolution:1.  Then you can see the ~63.9 N rolling force between the cylinder and ring.

 

  I also re-constrained the simulation a little bit by removing the zero acceleration imposed motion in Revolution:1, disabled the rolling joint and replaced it with a 2D contact joint between the roller and outer ring.  There you can see the contact (action / reaction) force calculated as ~64 Newtons (assembly attached).

 

  Hope this helps!  Please let us know if you have any additional questions, comments or suggestions.

 

Best regards, -Hugh
DS_NG_Centrifuge_rolling_Force.png

 

62_Newton_2DContact_Force_roller_2_Ring.png



Hugh Henderson
QA Engineer (Fusion Simulation)
Message 9 of 15
henderh
in reply to: henderh

At first when you mentioned pendulum, and had the zero acceleration imposed motion, I thought you wanted to know the reaction force at the center of rotation due to the centrifugal load of the spinning components.  I did a hand calculation and arrived at the same value as DS (158.1 N).  You can view the X or Y component of the Revolution :2 joint and see it matches exactly (images attached) Smiley Happy  

 

Warm regards, -Hugh



Hugh Henderson
QA Engineer (Fusion Simulation)
Message 10 of 15
maaduk
in reply to: henderh

Hi Henderh,

many thanks for your reply. I woul never imagine i could get one like this. Only when i try to open assemblies posted by you, i get Error message saying: "Error in reading RSe stream" so it won't open them. Is there any way to get over this? Another thing, i found out, that you impose motion also on revolution:2 by that little green cross near the joint sign. What motion you impose? Thanks

Madduk

Message 11 of 15
maaduk
in reply to: maaduk

Please, if you could have a look on attached. This is sort of a assembly with desired proportions. I can not get 2D contact working on this one. Thanks a lot for your help.

Message 12 of 15
JDMather
in reply to: maaduk


@maaduk wrote:

Hi Henderh,

... i get Error message saying: "Error in reading RSe stream" so it won't open them.

Madduk


You are using 2011 while Hugh saved in 2013.  Inventor files are not backward compatible.

I know you stated 2011 in your first post, but you should add this information to your signature.

 

Are you a student?  (students can download 2013 for free from http://www.autodesk.com/edcommunity )


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Certified SolidWorks Professional


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Message 13 of 15
maaduk
in reply to: JDMather

Yea, i will add it in there. I thought it might had been something like that. And no, i am not a student any more. I finished university last year. Now i am working for company in London.

Message 14 of 15
henderh
in reply to: maaduk

Hi Maaduk,

 

  The second simulation you posted up looks correct to me.

 As you've shown, the maximum reaction force on the roll head in the rolling joint is computed by DS as ~96.035 kN.

 

  Summing moments about the pivot point of the roll assembly (Revolution:2), and solving for the reaction force on the roll head comes out to be ~105 kN by my rough hand calculation.  (I used the combined CoG of the roll head and roll assembly as the point of application of the centrfugal force)


  I trust the Dynamic Simulation numbers more than my rough hand calculation...and this gives me confidence in both results, since they are somewhat close Smiley Happy

 

Warm regards, -Hugh

 

[Edit: add photo of hand calc]

 

  



Hugh Henderson
QA Engineer (Fusion Simulation)
Message 15 of 15
maaduk
in reply to: henderh

Hi Henderh,

many thanks for your help. All this was about calculating force by which roll head acts on the ring. We are upsizeing existing device and we would like to know if the bearings are big enough. You helped me a lot.

Martin

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