Why is significantly different maximum reachable velocity in ADAMS CAR 3D road for geometrically identical roads but once used in xml format and once used in crg+crgf format

I created ring road in xml format by the road builder in Adams-car and then converted this road to crg + crgf format. Then I run the 3D road using both the road formats. The maximum reachable velocity in curves is for the road in xml format about 20% higher than for the road in crg format. When I export the roads from Adams view in shell format they are identical.

Could anybody advise me where could be the problem?

0 Jesper Slattengren over 3 years ago

One of them is interpolating better and is therefore smoother. Just a guess.

Look at the vertical and lateral load on the tires and see if that can give you a clue.
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0 M Mueller over 3 years ago

Thank you for the hint. Is there any possibility to set the interpolation order?
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0 Jesper Slattengren over 3 years ago

The standard handling tire has a point contact, so not much you can do there.

But my guess is that the xml-road has a better interpolation while crg roads takes the surface as is without interpolation. But there are a lot I don't know about the crg roads.
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0 Martin Kieltsch over 3 years ago

Depending on road format and tire-model the coefficient of friction is not what you may think it is.

You could easily verify that by creating a flat piece of road and "testing" your tire-property with a tire-testrig.

Just do simple drive/brake/cornering and plot force vs. slip.

Up to my knowledge the crgf format is something that scales the friction solely for FTire - if you apply that to magic formula models it may not be used (i.e. using a "friction" of 1).

Even worse: depending of ADAMS & FTire version that algorithm had bugs.

And then there's always a great likelyhood that your "conversion" has gone wrong. Usually I'd expect a "ring road" being inclined and depending on the conversion method it may happen that you created a "flat" crg with a missing slope.

In that case cornering speed would differ, too.

(But as you have verified that the shells are identical, his may not appy to your case)
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