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Calculate approximately G-force applied on Car shock absorber

  1. Sep 12, 2012 #1
    I have to do some dataacquisition from a car with some accelerometers.

    4 accelerometers is placed on the wheels before the shock absorber. And i need to calculate the maximum applied G-force on the accelerometers.

    Just an approximately value, not taking in account the type of wheel, airpressure in wheel etc.

    Scenario 1:
    Steady speed of the car driving on normal tarmac is 110km/h.
    Weight of car is 2000kg
    The car is driving over a small bump with a height of 5cm

    Scenario 2:
    Steady speed is 50km/h
    Weight 2000kg
    The car is driving over a regular speedbump, approximately height of 30cm

    Seeing the bump on the wheel as if was a regular spring, i would calculate acceleration from
    A=5cm
    ω=sqrt(k/m) (not knowing the spring constant, i just took some samples from 0-500Hz as a value, whats realistic here?)
    a=-ω^2*A*cos(ω*t)
    with a.max being -ω^2*A

    and then divide final max acceleration with 9.8m/s^2. But this seem to give me abnorm large value of g-force.

    Any help, to how to calculate this the right way?
     
  2. jcsd
  3. Sep 13, 2012 #2
    The rise/run ratio of your bumps will have some determination of your G force.
    A slightly sloped bump gives less G force than a sharp bump, due to Ft.

    A 30 cm bump - this is a regular sped bump height???
     
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