Non-linear tire vertical stiffness pacejka2002

[VojtechBrychta]

Hello,

I'd like to ask you, do you know to introduce non-linear vertical stiffness to 2002pacejka tire model in A/Car? There is just a single number in all tire examples in Adams and I'm unable to find any parameter which could influence it. On the other hand, it seems strange that such a complex tire model wouldn't account for any vertical stiffness variation.

Thank you very much!

Have a nice day,
Vojtech

 

[GregLocock]

No, I don't know how to. I suspect the reason is that a MF tire is primarily designed to simulate handling type events. Looking through some test results a linear model seems fine at typical load/psi settings. If the tire is nearly flat a non linear curve would be needed.

 

[VojtechBrychta]

I'm working with truck tires and I noticed from the spec sheet of a given tire that the stiffness at 50% load is 20% lower than at nominal load (at constant pressure). I bet this could have an influence on handling as well when it comes to the load transfer during cornering/braking.

Do you know which tire model would be suitable for my application? I'm looking to perform a static roll over test. I don't want to go with Ftire due to a lack of data as well as simulation performance and Fiala seems to have the same problem as 2002pacejka.

Thanks a lot!
Vojtech

 

[GregLocock]

I think you'd be disappointed by ftire, at least the version I used gave identical results to pac for handling events (I may have used it wrong, I was interested in impacts, not handling). One approach might be to smooth the Flattrac data and then just interpolate off that, in n dimensions. This makes your tire files rather large but can be quicker than Pac, since essentially you are only doing simple maths.

What data do you have?