Road Load data without Wheel Force Transducers
Road Load data without Wheel Force Transducers
(OP)
I am trying to figure out whether there is a way of collecting RLD on a vehicle WITHOUT wheel force transducers (way too expensive) that I can then put into an ADAMs model to extract component load time histories. I am guessing accelerometers are not much use as there is no way of being sure of the mass the acceleration is applied to...
I'm sure people must have done this before WFTs, but I am struggling to think of a way that captures the loads in all directions.... Any thoughts would be appreciated.
I'm sure people must have done this before WFTs, but I am struggling to think of a way that captures the loads in all directions.... Any thoughts would be appreciated.





RE: Road Load data without Wheel Force Transducers
It is an order of magnitude more difficult than using WFTs, and very hard to be confident of your results.
Probably worth asking what you are actually tring to achieve?
Accelerometers are pretty neat, as a cheap correlation channel, but they are not very sensitive to modelling errors in my experience.
Cheers
Greg Locock
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.
RE: Road Load data without Wheel Force Transducers
Sounds like you are confirming the conclusion I was coming to, which is there a reason why people use wheel force transducers, and they are so expensive...
RE: Road Load data without Wheel Force Transducers
You could take an enormous brave pill (about the same size as a pineapple), measure the triaxial acceleration each side of the body side mount, multiply the double integrated displacement difference by the (frequency dependent) dynamic rate of the bush and hey presto, a force.
I wouldn't trust it.
Cheers
Greg Locock
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.
RE: Road Load data without Wheel Force Transducers
PS I like the double integrating idea; like so many methods in this area it sounds great in theory, but ......
RE: Road Load data without Wheel Force Transducers
Yes, we measure the suspension configuration by measuring the spindle location vertically, with stringpots, and the steer angle, with stringpots. That sets the arm geometry and you can then apply your forces correctly.
This is at once rather crude and perfectly sensible. It's not worth bleeding over road loads - run to run variation is of the order of 20%.
Cheers
Greg Locock
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.
RE: Road Load data without Wheel Force Transducers
Maybe I'll stick to 3g bump and hope for the best...although the more complicated analysis are always more fun!
Thanks for your help
RE: Road Load data without Wheel Force Transducers
I do agree, if I were designing a car for my own company I'd design to a series of static loads. 3g in Z is a bit light on in my experience for a road car. It will work for a race car.
Cheers
Greg Locock
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.