W.I.P. Grand Prix de Trois-Rivières road layout

Discussion in 'Tracks' started by NiTZHD, Jun 5, 2020.

  1. maruto

    maruto Member

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    Well Sir, thanks for the theory on friction coefs, it reminds me that my physic lessons from CEGEP are quite some years behind me, maybe you can clarify that for me...

    If i understand your note, we are interested here with the kinetic ( µk) of rubber against concrete (0.6 ... 0.85) vs rubber against asphalt (0.67)....(dry conditions) so in theory rough concrete has more grip than asphalt...

    looking at your google search i found that page that explains it simply:

    http://dev.physicslab.org/Document.aspx?doctype=3&filename=Dynamics_FrictionProperties.xml

    rubber on concrete : 0.68
    rubber on asphalt: 0.67

    rubber on iron casted plates: ? (can you help me with that case?)

    EDIT: found another source with different coef...
    (https://www.engineersedge.com/coeffients_of_friction.htm)



    I'll let the physical engine of Assetto corsa do the math, but we can translate that into the physical engine by attributing surface properties in relation of one another in a surfaces.ini file that will look like this:

    [SURFACE_0]
    KEY=ASPHALT
    FRICTION=0.97

    DAMPING=0
    WAV=
    WAV_PITCH=0
    FF_EFFECT=NULL
    DIRT_ADDITIVE=0
    IS_VALID_TRACK=1
    BLACK_FLAG_TIME=0
    SIN_HEIGHT=0
    SIN_LENGTH=0
    IS_PITLANE=0
    VIBRATION_GAIN=0
    VIBRATION_LENGTH=0

    [SURFACE_1]
    KEY=CONCRETE

    FRICTION=0.98
    DAMPING=0
    WAV=
    WAV_PITCH=0
    FF_EFFECT=NULL
    DIRT_ADDITIVE=0
    BLACK_FLAG_TIME=0
    IS_VALID_TRACK=1
    SIN_HEIGHT=0
    SIN_LENGTH=0
    IS_PITLANE=0
    VIBRATION_GAIN=0
    VIBRATION_LENGTH=0


    [SURFACE_2]

    KEY=PLATES
    FRICTION=0.92??

    DAMPING=0
    WAV=kerb.wav
    WAV_PITCH=1.3
    FF_EFFECT=1
    DIRT_ADDITIVE=0
    BLACK_FLAG_TIME=0
    IS_VALID_TRACK=1
    SIN_HEIGHT=0
    SIN_LENGTH=0
    IS_PITLANE=0
    VIBRATION_GAIN=0.4
    VIBRATION_LENGTH=1.5

     
    Last edited: Sep 14, 2020 at 4:19 PM
  2. Johnr777

    Johnr777 Moderator

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    Keep in mind AC doesnt do well when going over small sections with a big friction difference, all 4 wheels need to be on similar frictions.
     
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  3. physicsimulation

    physicsimulation New Member

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    Your engineers edge document is interesting.

    I don't have definition for the "FRICTION" parameter within Assetto Corsa physical engine but, IMHO, I would put dry static coefficient of material since the driver would control acceleration (+ or -) up to the static slip ratio limit (see Vr=0 to Vs in my graph). This section has linear static coefficient upon slip ratio, therefore very easy to calculate.

    IMHO, the engine could modify the "FRICTION" parameter dynamically when it's raining, icing, snowing, colder, warmer, ...

    The slip ratio, or the relative speed, limit is function of the tire rubber compound and thread template (slick ... 4x4 ... paddle). Is Assetta Corsa physical engine handle this car parameter ?

    To conclude, I would use these FRICTION values [static dry condition]
    Rubber - Asphalt : 0.90 ( like street asphalt, in GP3R)
    Rubber - Soften concrete : 0.60 (like kart concrete or board walk or painted vibrator ?)
    Rubber - Rough concrete : 1.00 (like GP3R concrete in curves)
    Rubber - Rubber : 1.15 (like track with rubber deposit)
    Horseshoe - Rubber : 0.68 (like rubber on plates ???)
    Rubber - Grass : 0.36 (not pertinent for GP3R classic track)
     

    Attached Files:

    maruto likes this.
  4. Martin Dupuis

    Martin Dupuis New Member

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    Thanks, I did try it out yesterday and I find it very bumpy too. Did you watch lilSki's track building videos ? I think he goes over smoothing the lidar data in his first or second video. The whole series is just a treat. Highly recommended !
     
  5. maruto

    maruto Member

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    yeah, i don't want anything fancy or unusual, i'll stay within kunos margins for friction materials ( maybe use this famous corner as reference...)

    bgr01.jpg

    and i can try @physicsimulation hierarchy:

    Concrete>Asphalt>Plates>Curbs

    knowing that those numbers can easily be tweaked later.

    Right now i just need to split and rename correctly the phys mesh according to those different materials.


    Yeah, the AC engine take's all that into acount, before a race you can tweak almost every parameters, temperature, time, track state ( green, dusty, fast, wet) those parameters then affects the initial friction parameter set in the track surface.ini file.

    and of course, every car has different tyre parameter ( slick, thread,....etc) that affect the car grip and handling..

    this engine is more than 7 years old but has been so smartly build it is still in 2020 one of the most loved.
    So powerful and versatile.
    ( million thanks to Kunos)
     
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