cancel
Showing results for 
Search instead for 
Did you mean: 
cancel
Showing results for 
Search instead for 
Did you mean: 

Spring simulation questions

scohen-2
1-Newbie

Spring simulation questions

Hi

I created a simple macpherson strut with a spring but no damper and applied gravity only.

the simulation ran fine but then I found that the system is damped (see attached graph).

Why?

I applied no damping and no friction, so why is it slowing down?

Thanks!


This thread is inactive and closed by the PTC Community Management Team. If you would like to provide a reply and re-open this thread, please notify the moderator and reference the thread. You may also use "Start a topic" button to ask a new question. Please be sure to include what version of the PTC product you are using so another community member knowledgeable about your version may be able to assist.
9 REPLIES 9
ChrisKaswer
14-Alexandrite
(To:scohen-2)

Turn gravity off and compare its results to the same displacement curve you've already shared as the .jpg image.

ok, so I ran the simulation again.

first time for 50 sec with gravity turned off

Second time with gravity on for 500 sec

In both cases the system eventually relaxes

My question remains, why?

50+second+spring+sim.jpg500+second+spring+sim.jpg

ChrisKaswer
14-Alexandrite
(To:scohen-2)

OK, that's unusual. With gravity and friction off, a simple spinrg-mass system should oscilate indefinitely. Can you share your model?

Educational version

ehaenen
4-Participant
(To:scohen-2)

Shai

Unfortunately I cannot open your files, because I have a full version, this doesn't open educational.

Please check whether your analysis happens to have structural damping selected.

Then switch this off, or set to 0%

Erik

Where would I make that selection?

I couldn't find the option in the menues

Is it a selection that i make for each part or the whole assembly?

ehaenen
4-Participant
(To:scohen-2)

You do that in the time response analysis definition, in the bottom of the form: damping coefficient

dyna_ana.jpg

ChrisKaswer
14-Alexandrite
(To:ehaenen)

Erik,

This is an MDO analysis, not a Simulate dynamic analysis. Only rigid bodies are considered.

I'll try a simple, similar analysis and see what I get, as I've got the commercial version as well and can't open your posted files.

Chris

ehaenen
4-Participant
(To:ChrisKaswer)

Oops

Didn't see that, wasn't paying enough attention.

Thanks Chris

Announcements
Attention: Creo 7.0 Customers
Please consider upgrading
End of Life announcement here.

NEW Creo+ Topics:
PTC Control Center
Creo+ Portal
Real-time Collaboration