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Discussion Starter · #1 ·
RACING 101....1st QUIZ

OK.... Just for fun ...and let's be honest....don't go look it up, this isn't an open book test.

Let's see who knows what it is or thinks they know what it is.


Define STICTION.


Hint #1: It has nothing to do with tire adhesion.

Hint #2: A racer seeks to reduce STICTION.

You have 24 hours to think it over.
Answer will be posted tomorrow at Noon EDT
 

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Resistance to the starting of movement or motion :cheers:
 

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Static coefficient of friction is greater than dynamic coefficient so it takes more force to get mass moving than it takes to sustain movement.
 

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It's not "Static Friction", it's "Sticky Friction".

Stiction not a "real" term so it will defy actual definition. It's commonly used to refer to static frictional forces that are caused by secondary contributors, i.e., not the frictional force between two surfaces but the force between those surfaces and an intervening lubricant.

Lubricants (like all fluids) have surface tension. The force necessary to overcome that surface tension looks a lot like static friction, but it can be significantly greater than the "natural" coefficient of friction between the lubricant and lubricated surfaces.

Stiction is particularly problematic where tolerances are very tight.

I make disk drives for a living. The spacing between the recording head and disk surface is measuring in fractions of a µInch (or nanometers if you like). The static friction between the head and disk surface is generally quite low, the surface of the disk is coated with a lubricant. But if a head is parked on the surface of the disk for extended periods, the static friction (force required to get the head to break free of the disk surface so the spindle motor can spin) goes up significantly. The friction isn't really changing at all, of course, but given enough time, lubricant will fill in the gaps between the face of the head and the surface of the disk. The effect of the resultant surface tension necessitates a significantly greater amount of force to get things moving. We have a special name for this effect, it's called "Dwell Stiction", but it's stiction just the same.

I wouldn't bet on it, but if I had to guess, I'd guess that it was actually the disk drive industry that coined the term.
 

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I, too, learned the term from the disk drive industry. It was the term we would give to disk drives that would not spin back up after power down. These were typically old drives. The clients of course would have a ton of data they needed, so we came up with a magic trick.

30 minutes for the disk drive in the freezer, we would then hold the drive in our hand and flick the drive in a rotation to get the platter(s) loose. We would then quickly reinstall the drive, power up, and then as quickly as possible copy off all valuable data... client happy!!! :guiness: :guiness: :guiness:


PS. I learned of this term and technique almost 20 years ago.
 

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i cheated- i looked it up in the "stictionary" :lol:
 

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Hint #1: It has nothing to do with tire adhesion.
Ah, but it does! Although Rocketsled's description of "stiction" as it applies to mechanics is correct, the term is also used to describe tire adhesion.

The force required to slide a tire is called the adhesive limit of the tire, or "stiction", which is a slang term combining "stick'' and "friction.'' This law, in mathematical form, is F ≤ µW where F is the force with which the tire resists sliding; µ is the coefficient of static friction or coefficient of adhesion; and W is the weight or vertical load on the tire contact patch. Both F and W have the units of force (remember that weight is the force of gravity), so µ is just a number, a proportionality constant. This equation states that the sideways force a tire can withstand before sliding is less than or equal to µ times W. Thus, µW is the maximum sideways force the tire can withstand and is equal to the stiction. We often like to speak of the sideways acceleration the car can achieve, and we can convert the stiction force into acceleration in G's by dividing W by, the weight of the car. µ can thus be measured in G's.

The coefficient of static friction is not exactly a constant. Under driving conditions, many effects come into play that reduce the stiction of a good autocross tire to somewhere around 1.10G. These effects are deflection of the tire, suspension movement, temperature, inflation pressure, and so on. But the proportionality law still holds reasonably true under these conditions. Now you can see that if you are cornering, braking, or accelerating at the limit, which means at the adhesive limit of the tires, any weight transfer will cause the tires unloaded by the weight transfer to pass from sticking into sliding.
 

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You all are missing the point here relative to cars. There is no getting away from seal friction in a shock as it stops and starts and since the "stiction" (which is static friction) is a non-lineraity in the control loop equations. This is more of course than seal friction since it includes ball joint, tie rods etc, dynamic versus static friction. This is one reason F1 guys use flexures rather than heim joints. Flexures have a spring constant, but zero friction except for the material hysterisis. You guys in the disk drive business could have or probably do now, use flexures to help with access time and/or positioning errors. I know this crap, because at TRW when I was a structural dynamics analyst for satellite antennas we had this issue. When you tried to move and point a sensor or antenna, the damn stiction made it a bitch to get it right because when you added enough force to move it initially, it would overshoot for small movements. The solution we used was to get rid of dynamic bearings altogether and use flexures instead where possible. This becomes relavant to our cars because the stock suspension bushings are flexures and urethane bushings are dynamic bearings. The urethane has the advantage of less deflection, but ride over expansion joints or small pot holes suffers. I guess there is always a trade-off to everything....
 

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It's what I try to do to my girlfriend Tiction as much as possible.
;)
 

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DJWorm said:
RACING 101....1st QUIZ



You have 24 hours to think it over.
Answer will be posted tomorrow at Noon EDT
It's been 48 Hours or so. You still looking up the answer :rofl:
 

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Discussion Starter · #17 · (Edited)
OH, sorry my bad.

Boy, we have a lot of very smart and knowledeable people on this Forum.

Congratulations, the 1st 5 answers were immediately correct. Those 5 ALL win a new C6 Z06. You can go to your local Chevy Dealer to pick it up. Just tell them I sent you, I'm sure they will hand one right over to you. He He (sic)

Seriously, (or not), as so aptly described by the first 5 responders, STICTION is a term used in auto racing and most recently in the computer industry. It is a combination of STATIC and FRICTION and attempts to encompass the effect of Static Inertia and Static Kinetic Energy on initially static moving parts as described by Newton
"A body at rest tends to stay at rest."

Specifically it is used to describe the effect of 2 surfaces against each other.
"Unlubricated bearings have more initial STICTION than lubricated bearings."
"Teflon reduces STICTION."
"A Hard Disc spins up mush faster if you reduce STICTION."
"Racers try to reduce STICTION as much as possible."

I guess GRIP would by a synonym.

ADHESION might also be a synonym but adhesion most often refers to the GRIP or STICTION between a stationary and a moving or dynamic surface such as a road surface and a tire

This addresses the mechanical effect of Static Friction between 2 surfaces. I am wondering if there is not also a Quantum factor such as the Weak Gravitational Force or Magnetic forces involved. Maybe we can solve the Unified Field Theory here.

I am sure there is a term to describe the increased STICTION Viscosity of the MagneticRheologic fluid in the new MagneRide shocks as it changes. As yet I have not seen STICTION applied to or refered to dynamically.

Note that the Rheo prefix denotes that there is a change, specifically in the viscosity but doesn't really describe the effect of the increased viscosity.

This is a first folks !!

Possibly DYNOSTICTION , HYDROSTICTION, MAGNASTICTION, ELECTRO-MAGNETICSTICTION or RHEOMAGNETICSTICTION could be used.
 
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