Rotational joints

Multibody dynamics technique, real objects and its dynamical models

Rotational joints

Postby Polacsek » Wed Feb 21, 2018 10:48 pm

Hello,
I have a problem with rotational joints. I'm trying to make a bicycle model with 2 spring and 2 dampers, (attached file) and my problam is that, if I put one of the rotational joint at one end of the bicycle frame, it rotates just fine around that joint. But if I put on the other rotational joint at the other side of the frame, the UM Simulation says "Integration step too small" if I put a delayed sinusoidal excitation on each damper/spring. Each joint works fine alone, but I can't make them work together.

Regards,
Balazs
Attachments
Bicycle.zip
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Polacsek
 
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Re: Rotational joints

Postby Dmitry Agapov » Mon Feb 26, 2018 3:29 pm

Hello Balazs
Probably you are trying to link the bicycle frame to the base with 2 rotational joints. In this case the frame will not have any degrees of freedom and cannot move at all.
I advise you to learn our lessons before development your models. You can find them here (by default): c:\Users\Public\Documents\UM Software Lab\Universal Mechanism\8\manual\Getting Started\gs_um.pdf
Best regards
Dmitry
Dmitry Agapov
UM Team
 
Posts: 1
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Re: Rotational joints

Postby Polacsek » Tue Feb 27, 2018 11:46 am

Hello Dmitry
Thank you for your response. The rotational joint where good, I messed up two translation joint which caused the problem, which indeed resulted in an over-defined model. Thanks again.
Regards
Balazs
Polacsek
 
Posts: 2
Joined: Wed Feb 21, 2018 10:20 pm


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