What is the relationship between tire physics and slip angle?

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Discussion Overview

The discussion revolves around the concept of slip angle in relation to rubber tires, exploring its effects during cornering, and the implications for vehicle handling. Participants share their understanding of slip angle, its significance in tire performance, and its relationship to different types of vehicles.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Some participants describe slip angle as the difference between the direction a tire is pointing and the direction it is moving, noting its role in cornering dynamics.
  • One participant mentions that the slip angle can have both positive and negative effects, depending on the circumstances, suggesting it is beneficial until a certain threshold is crossed.
  • Another participant references the concept of understeer and oversteer, explaining how different slip angles at the front and rear wheels affect vehicle handling during turns.
  • A participant shares insights from simulations, indicating that the slip angle can be modeled as a lateral force that varies with the angle, while also acknowledging the complexity of real-world tire behavior.
  • Some participants suggest further reading and resources, including articles and books, to deepen understanding of tire physics and slip angle.

Areas of Agreement / Disagreement

Participants express varying levels of understanding and interpretation of slip angle, with some agreeing on its basic definition and effects, while others highlight different perspectives on its implications for vehicle dynamics. The discussion remains unresolved regarding the optimal conditions and effects of slip angle.

Contextual Notes

Some claims made by participants depend on specific vehicle types (e.g., motorcycles, race cars) and driving conditions, which may not be universally applicable. There are also references to external resources that may provide additional context but are not universally agreed upon.

Who May Find This Useful

This discussion may be of interest to automotive engineers, racing enthusiasts, and individuals studying vehicle dynamics or tire performance.

fog37
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Hello everyone,

Does anyone know what the slip angle is in relation to rubber tires? What is its effect? Is it a positive or negative effect?

My basic understanding is that when a tire is cornering, the tire does not point directly along the curved direction of motion but is slightly twisted, since it is made of rubber, and points slightly towards the outside of the curve...
 
Engineering news on Phys.org
Have you Googled "Tyre Slip Angle" yet".
 
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fog37 said:
Hello everyone,

Does anyone know what the slip angle is in relation to rubber tires? What is its effect? Is it a positive or negative effect?

My basic understanding is that when a tire is cornering, the tire does not point directly along the curved direction of motion but is slightly twisted, since it is made of rubber, and points slightly towards the outside of the curve...
The tire points inward. The tread distorts as the wheel rolls. The tire must point further in the desired turn direction than the vehicle will actually turn.
 
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Does anyone know what the slip angle is in relation to rubber tires?
yes

What is its effect?
could be good until it goes to bad

Is it a positive or negative effect?
positive until it goes to negativeMy basic understanding is that when a tire is cornering, the tire does not point directly along the curved direction of motion but is slightly twisted, since it is made of rubber, and points slightly towards the outside of the curve...

on a motorcycle? which tire?
on a race car are you talking about the right front in a left turn corner or the left front tire in a left turn?
Or are you talking about the rear tires?

i suggest you read race car suspension class ...above...see page 4 post #62
page 12 post # 228
page 24 post # 470 lumpy and the down force
page 41 post # 811 centrifugal vs centripetal
 
The slip angle is the difference between the direction that a tire is pointing and the direction that it is moving. My experience with it was in simulations that only had to be believable, not necessarily accurate. We modeled it as a lateral (versus tire point direction) force that was a linear function of the slip angle. When the tire points more to the left, the force is to the left.
I assume that a real analysis of turning force would require detailed understanding of the tread design and pattern. It seems that a tire company could more easily set up experimental fixtures than rely on analysis, but I have no authoritative knowledge of that.
 
I read an ancient book -The Sportscar by Colin Chapman. He explained the relevance of slip angle. When a car is cornering, both front and rear wheels have a slip angle. If the front wheel slip angle is greater than the rear wheel slip angle then you have to steer harder into a corner to go where you want. This is called Understeer and is the safest arrangement but, of course, it reduces the cornering ability - not good for racing and being flash. A 'manoeuvrable' car will have neutral or even Oversteer and the rear wheels will slip more, allowing the back of the car to hang out and, eventually spin. This accounts for the trick which rally drivers use when they use 'reverse lock on the way round a bend fast.
The slip angle is affected, not surprisingly, when power is applied to a wheel; a rear wheel drive car tends to oversteer (we've all been there) and a FWD car tends to understeer, which is more comfortable for the nerves of the passenger.
PS A google search will yield masses of interesting facts about this.
 
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Thanks everyone. All very useful.

I appreciate the Michelin article from cosmik debris. Learning a lot.
 

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