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Selecting appropriate damper

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OGR34

Automotive
Jan 18, 2015
24
I've been a bit lost figuring out what damper I should be using for the front suspension I am designing. Right now I'm running a wheel rate of 60 lbf/in at the front with a ride frequency of 1.2254 Hz. The front is also supporting a sprung mass of 391.68 lbf. Comfort is the end requirement of the design where the car will be operating at city and highway speeds of around 60km/h and 100km/h.

From what I've been reading a damping ratio of about 0.2 is suitable for a passenger car to maximize comfort in bump. I am aware that just working with that damping ratio all throughout the force velocity curve is not ideal because the ride can be very uncomfortable at high velocities and I am also aware that the damping should be higher during rebound compared to bump. Currently I am trying to work towards a force velocity curve that has a similar profile as shown in the attachment I've uploaded. However, I am having difficulty determining how much more damping I want in rebound compared to bump as well as where I should have the split between high and low velocity.

Another thing that I'm concerned about is when I do actually finalize my desired force velocity curve, how can I select a damper on the market that will behave similarly to that curve? I've been looking around in catalogs but all they help you with is the sizing and choosing the appropriate damper for a particular model of vehicle and I don't believe manufacturers are willing to reveal their force velocity plots for their dampers because it may be confidential information. Any help would be appreciated! [smile]
 
 http://files.engineering.com/getfile.aspx?folder=ed7b8c88-8cbd-44d8-bd66-258be5a9c8e1&file=Capture.PNG
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There are proprietary methods for selecting damper sizes based on the usual inputs, but I don't think there are methods that a ride engineer would concede were worthwhile as more than first guess for developing force vs velocity curves, and certainly not valving.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376
 
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