COSMOSMotion questions

Sep 07, 2004 4 Replies

Rate this thread:

Paul 21 years ago

I am trying to simulate a single degree of freedom system with no damping

formatting link

but for some reason results show damped vibrations. I have not defined any friction on joints so where is this damping coming from? Is there a default damping defined somewhere?

If you would like to look at the model it is here:

formatting link

thank you for your help

Paul

Vote

P. 21 years ago

Can you provide a frequency amplitude plot and the parameters of your system (or what you think they are). m, k

Paul wrote:

formatting link

Vote

Denny Trimble 21 years ago

Paul, I think you've stumbled on a severe problem in the new release of Cosmos Motion. I played around with your model, and a few of mine, and found these things out:

1) Running different solvers gives different results on this simple system 2) Different sample rates gives different results (dramatically changes system from damped to unstable)

Check out the results with different solvers and sample rates:

formatting link

Not good!

I'm running Education Edition 2004-2005, by the way.

-Denny Trimble University of Washington

formatting link

Vote

Paul 21 years ago

m = 0.192kg k = 500N/m

also, how do you define initial displacement?

thanks

Paul

formatting link

Vote

Paul 21 years ago

m = 0.192kg k = 500N/m

thanks

Paul

formatting link

Vote

Join the Discussion

Have something to add? Share your thoughts — no account required.

Didn't find your answer?

Ask the community — no account required