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Angular momentum in mechanism correct?

jojo
1-Newbie

Angular momentum in mechanism correct?

Hi,

 

I am wondering if the angular momentum is correctly calculated in the mechanism module.

 

I am wondering this because when I spin a disk through it center axis (this part is the only moving part see figure below) the angular momentum reported for the system is different when changing the location of the spinning disk in the global coordinate system.

 

When checking the results analytically the calculations are correct when the disk center coincides with the global y-axis.

 

The angular momentum about the origin (H_o) should be calculated as the angular momentum about the center of gravity (H_g) plus the center of gravity position vector (r_g) cross the velocity of the center of gravity (V_g) times the mass (m):

 

 

H_o=H_g + (r_g x V_g)m

 

 

Since the velocity of the center of gravity (V_g) is zero, the second term vanishes. Hence the angular momentum reported should be constant no matter the center of the spinning disk.

 

 

Anyone getting the same results?

 

Best regards,

Joel Johansson

 

AngularMomentum.jpg


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1 ACCEPTED SOLUTION

Accepted Solutions
jojo
1-Newbie
(To:jojo)

I got this mail from Adam Haas 2012-11-12:

Joel,

Unfortunately you are correct; there is a problem with the analysis. We have filed a Software Performance Report (SPR #2156415 HIGH, A) and the bug will be fixed in a future build code of Creo 2.0. It was given a High priority and the Mechanism development team is pretty good at fixing things so hopefully it will be corrected soon.

Thanks for finding this and I’m sorry I don’t have method for fixing it now.

Sincerely,

Adam

View solution in original post

1 REPLY 1
jojo
1-Newbie
(To:jojo)

I got this mail from Adam Haas 2012-11-12:

Joel,

Unfortunately you are correct; there is a problem with the analysis. We have filed a Software Performance Report (SPR #2156415 HIGH, A) and the bug will be fixed in a future build code of Creo 2.0. It was given a High priority and the Mechanism development team is pretty good at fixing things so hopefully it will be corrected soon.

Thanks for finding this and I’m sorry I don’t have method for fixing it now.

Sincerely,

Adam

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