I´m trying to find on TGM file (CPM) the equivalent for TemporaryBristleDamper on old tire model, tried with almost everything and i´m a bit lost here. I want to higher rolling resistance on the tire to be able to reduce speed, is this possible on CPM?
It's now done via BaseDamperPerUnitArea=(2800,1400,3100) To convert from one to the other, you can multiply the old values by 1/(treadwidth/7*(circumference/72)). It'll usually need to be around 1000x higher than the old value. We now also have a speed dependent contribution to rolling resistance, HystereticVerticalDamperPerUnitArea=5000 You may need to reduce the middle value from BaseDamperPerUnitArea=(2800,1400,3100) if you include "HystereticVerticalDamperPerUnitArea". This variable will add more low speed resistance.
Thank you Michael, i assume that the HystereticVerticalDamperPerUnitArea= is already working with latest CPM?
Yes, it's been around for the last few builds, at least. IIRC, the first car to get it was the V1.60 2012 FISI.
Michael, would you please elaborate on those values and what they all do? Working on a set of tires right now, and I would love to know more. You could help me out quite a bit here, thanks.
Yes Michael, I would like to read more about it, as I'm working on CPM tyres too. Thanks for your help.
Bristles can move in 3 dimensions, and we can specify separate damping properties for each of those. If you take: BaseDamperPerUnitArea=(<x>,<y>,<z>) In ISI dimensional space, x is lateral, y is vertical, z is longitudinal. Per unit area means, this amount of damping per square meter, and of course, by definition damping resists any movement (or change in position, more accurately). So if you have 0.04m² patch area (visible in ttool, BTW), and 2000 damping per unit area. Then you end up with 2000*0.04=80. That's 80 N of resistance, per m/s in whatever direction the force is applied. The tyre is not uniform, so it's hard to predict the rolling resistance that you'd get, and it's better to check out the vertical bristle wattage in ttool. HystereticVerticalDamperPerUnitArea, clamps the speed to 1 m/s, and so gives more rolling resistance at lower speeds. This also effectively decreases at higher speeds, all else being equal (i.e. constant load). That's becase the tyre spring rate increases with rotation speed so overall deflections are reduced. Typically, I find the HystereticVerticalDamperPerUnitArea should be ~6x higher than the middle value of BaseDamperPerUnitArea. Hope this helps. I'm also planning to cover this lightly in a couple weeks in my blog.
