best practices in multibody model debugging
best practices in multibody model debugging
(OP)
Hi all,
I'm quite new in multibody modeling and I spent the most of time in debugging my model, trying to simplify as much as possibile the model. Is there any systematic way or best practices to debug big multibody models?
thanks
I'm quite new in multibody modeling and I spent the most of time in debugging my model, trying to simplify as much as possibile the model. Is there any systematic way or best practices to debug big multibody models?
thanks





RE: best practices in multibody model debugging
As an example with a car I'd start by making sure each suspension works on a K&C test before assembling the suspension to a body and running full vehicle tests with tires. Then I'd add the powertrain and so on. Then I'd replace the smooth road with a 3d road surface. At some point I might need aero, so I'd start with still air, and then add a crosswind. Then I'd replace linear elastic engine mounts with hydraulic ones. And so on and so forth.
Also a modal analysis is a very useful check on your model.
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?
RE: best practices in multibody model debugging
When my vehicle was first connected up, it misbehaved really badly, but an animation of the first fraction of a second showed the problem: 180deg initial twist on the drive shafts - the car wanted to wheelie off backwards.
- Steve
RE: best practices in multibody model debugging
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?
RE: best practices in multibody model debugging
In my big model, the engine was installed at a small angle to the global vertical (15º). That was too much initial twist when multiplied through all the gears and shafts, which were all started at zero to the global vertical. So I installed the engine system in a "cradle", which gradually rotated it back by 15º while the starter motor was starting the engine. Happy days!
- Steve
RE: best practices in multibody model debugging
I use to do almost the same and also give insight the model, but it's very time consuming and I admit that I'm non that fast in modeling. Do you use the design of experiment for the debugging?
RE: best practices in multibody model debugging
For instance I did use a DOE to get from blue curve to the green one in this case, trying to get better agreement to the red line which is the real vehicle with the same SWA time history.
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?
RE: best practices in multibody model debugging
thanks for your reply. For debugging I mean the analysis of checking mistakes inside the model. For improving the correlation with measured result I use the optimization and sometimes I use the DOE just to find a good starting point for the optimization.