Yawing Trailer loses it

[BrianE22]

The trailer being towed by the car in front of me had the trailer yawing side to side. I've seen this before but have never seen one go unstable. This one did. Sure looks like an oscillating spring mass system - usually critically damped, underdamped in this case. I was wondering what the significant springs and masses were for this oscillation? I'm guessing yaw stiffness of the tires is the spring and the mass is the yaw inertia of the trailer. Damping is tire friction to road maybe?

Just a little utility trailer, no load in trailer. I'm not sure what the wind was like.

 

[GregLocock]

It's a bit more complicated than "yaw stiffness of the tires is the spring and the mass is the yaw inertia" but essentially, yes. I had it on a caravan where the loader had put jerrycans of water at the rear of the caravan. here's an investigation

https://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.1029.4946&rep=rep1&type=pdf

Unfortunately the only analysis I have seen (it is not of direct interest to me) is proprietary. The big problem we have is that there are an infinite number of configurations of trailers out there.

Cheers

Greg Locock


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[SwinnyGG]

https://www.youtube.com/watch?v=i2fkOVHAC8Q

Above link is a favorite that simply demonstrates how a badly loaded trailer can kill you

 

[GregLocock]

I found this. Old school dynamics!

https://www-nrd.nhtsa.dot.gov/pdf/esv/esv17/Proceed/00098.pdf

Cheers

Greg Locock


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