Re: Do you know of engineering papers for what people call brake rotor 'warp'?

[Joe Mastroianni]

On Fri, 15 Feb 2013 16:48:16 -0800, jim beam wrote:

> "thermo-elastic instability hotspots"?????? if you mean "heat
> distortion", then say so - don't try to confuse the proles.

The proletariat be damned, I reach out to the literati to explain
what "really" causes brake judder (because it's not rotor warp)!

Googling, I found these on the bimmer boards so far that I'm reading:

"Aspects of disc brake judder"
Proceedings of the Institution of Mechanical Engineers,
Part D: Journal of Automobile Engineering
http://pid.sagepub.com/content/217/6/419.full.pdf

Analysis of the vehicle brake judder problem by employing a simplified source–path–receiver model
Acoustics and Dynamics Laboratory,
Department of Mechanical Engineering,
The Ohio State University, Columbus, Ohio, USA
http://www.researchgate.net/publication/233988829_Analysis_of_the_vehicle_brake_judder_problem_by_employing_a_simplified_sourcepathreceiver_model/file/79e4150e7d38711887.pdf

A Parametric Study of Brake Roughness
Robert Bosch Corporation
http://sem-proceedings.com/20i/sem.org-IMAC-XX-Conf-S17P04-A-Parametric-Study-Brake-Roughness.pdf

Judder, Diagnosis, & Prevention,
Mohamed Khalid Abdelhamid, AlliedSignal Automotive, Europe
http://sem-proceedings.com/14i/sem.org-IMAC-XIV-14th-Int-14-5-5-Judder-Diagnosis-Prevention.pdf

Improved mathematical models of vehicle brake judder and experimental observations
Osman Taha Sen, Rajendra Singh
Acoustics and Dynamics Laboratory, Department of Mechanical and Aerospace Engineering,
The Ohio State University,
http://www.mecheng.osu.edu/adl/files/adl/C12-1.pdf

Judder vibration in disc brakes excited by thermoelastic instability
Oscar Altuzarra, Enrique Amezua, Rafael Avilés, Alfonso Hernández, (2002),
Engineering Computations, Vol. 19 Iss: 4, pp.411 - 430
http://www.ehu.es/compmech/welcome/doc/Paper%20867%20Engineering%20Computations.pdf

Experimental Analysis of Disc Thickness Variation Development in Motor Vehicle Brakes
School of Aerospace, Mechanical & Manufacturing Engineering (SAMME)
http://researchbank.rmit.edu.au/eserv/rmit:6260/Rodriguez.pdf

Thermal Brake Judder Investigations Using a High Speed Dynamometer
David Bryant, John Fieldhouse, Andrew Crampton and Chris Talbot, University of Huddersfield
http://eprints.hud.ac.uk/3878/1/2008-01-0818.pdf

Braking Process in Automobiles: Investigation of the Thermoelastic Instability Phenomenon
M. Eltoukhy and S. Asfour, Department of Industrial Engineering, College of Engineering, University of Miami
http://cdn.intechweb.org/pdfs/5380.pdf

Brake Vibration and Noise - A Review and Discussion
Dihua Guan, State Key Laboratory of Automotive Safety and Energy,
Tsinghua University, Beijing, China
http://www.acoustics.asn.au/conference_proceedings/ICA2010/cdrom-ICA2010/papers/p46.pdf

NVH Simulation Technology for Disc Brake Calipers
Hitachi, Suzuki Yoichi Kumemura Hayuru Inoue Yuichi Takagi Shinji Suzuki
http://www.hitachi.com/ICSFiles/afieldfile/2009/12/25/r2009_07_107.pdf

SURFACE TEMPERATURE DISTRIBUTION IN A COMPOSITE BRAKE ROTOR
A.A. Adebisi1, M.A. Maleque1 and Q.H. Shah
Department of Manufacturing and Materials Engineering
http://ejum.fsktm.um.edu.my/article/1146.pdf

DISCUSSION OF THE CHARACTERISTICS OF BRAKE JUDDER AND THE NECESSARY DATA ACQUISITION SYSTEM FOR COMPLETE ANALYSIS
D. Bryant, A. Crampton, J. Fieldhouse and C. Talbot
University of Huddersfield, Queensgate, Huddersfield HD1 3DH, UK
http://eprints.hud.ac.uk/3797/1/10_PAPER_Final_D_Bryant.pdf

Order domain analysis of speed-dependent friction-induced torque in a brake experiment
Osman Taha Sen, Jason T. Dreyer, Rajendra Singh
Acoustics and Dynamics Laboratory,
Department of Mechanical and Aerospace Engineering,
The Ohio State University, Columbus, OH 43210, USA
http://www.mecheng.osu.edu/adl/files/adl/J187.pdf

[jim beam]

On 02/15/2013 05:44 PM, Joe Mastroianni wrote:
> On Fri, 15 Feb 2013 16:48:16 -0800, jim beam wrote:
>
>> "thermo-elastic instability hotspots"?????? if you mean "heat
>> distortion", then say so - don't try to confuse the proles.
>
> The proletariat be damned, I reach out to the literati to explain
> what "really" causes brake judder (because it's not rotor warp)!
>
> Googling, I found these on the bimmer boards so far that I'm reading:
>
> "Aspects of disc brake judder"
> Proceedings of the Institution of Mechanical Engineers,
> Part D: Journal of Automobile Engineering
> http://pid.sagepub.com/content/217/6/419.full.pdf

quickly scanning, i see nothing on caliper asymmetry.

>
> Analysis of the vehicle brake judder problem by employing a simplified source–path–receiver model
> Acoustics and Dynamics Laboratory,
> Department of Mechanical Engineering,
> The Ohio State University, Columbus, Ohio, USA
> http://www.researchgate.net/publication/233988829_Analysis_of_the_vehicle_brake_judder_problem_by_employing_a_simplified_sourcepathreceiver_model/file/79e4150e7d38711887.pdf

that one presumes disk thickness variation, nothing on caliper dynamics.

>
> A Parametric Study of Brake Roughness
> Robert Bosch Corporation
> http://sem-proceedings.com/20i/sem.org-IMAC-XX-Conf-S17P04-A-Parametric-Study-Brake-Roughness.pdf

etc.

i'll try to look at the rest, but seriously, most people who don't know
are chasing their tails. those that do know aren't going to say much
because they're not going to do two things:

1. they're /definitely/ not going to kill a cash cow which is selling
new disks way before they're worn.

2. they're not going to stop using single-sided calipers because they're
essential to macpherson strut suspension being able to have a negative
scrub radius.

so you're just going to have to keep sucking it up and coughing it up.


--
fact check required

[Joe Mastroianni]

On Fri, 15 Feb 2013 18:34:14 -0800, jim beam wrote:

> i'll try to look at the rest, but seriously, most people who don't know
> are chasing their tails. those that do know aren't going to say much
> because they're not going to do two things:
>
> 1. they're /definitely/ not going to kill a cash cow which is selling
> new disks way before they're worn.
>
> 2. they're not going to stop using single-sided calipers because they're
> essential to macpherson strut suspension being able to have a negative
> scrub radius.

I'm reading those papers, as you are, and they talk about hot and cold
judder and they speak of high and low speed judder (mostly we're talking
around 100Hz here so that's low speed judder).

There's a lot of stuff about hot spots (I 'think' that's thermoelastic
instability) and disc thickness variation (I 'think' that's uneven
pad deposition) and axial runout (I think that's plane old runout).

It will also take me a while to read them all, but I don't see anything
(yet) about the single piston caliper design.

[jim beam]

On 02/15/2013 07:06 PM, Joe Mastroianni wrote:

well, it's pretty obvious if you consider the relative masses as a
dynamic system being agitated by a waving disk sat in its middle.


--
fact check required

[dsi1]

On 2/15/2013 5:06 PM, Joe Mastroianni wrote:
>
> I'm reading those papers, as you are, and they talk about hot and cold
> judder and they speak of high and low speed judder (mostly we're talking
> around 100Hz here so that's low speed judder).
>
> There's a lot of stuff about hot spots (I 'think' that's thermoelastic
> instability) and disc thickness variation (I 'think' that's uneven
> pad deposition) and axial runout (I think that's plane old runout).

I believe that what happens is that there's some transference of pad
material onto the iron disk at a molecular level. You can't measure it
because we're not able to measure tolerances to that level. It does,
however effect the frictional coefficients between the two surfaces at
localized areas. This causes the hot spots. Well, that's my
understanding about it anyway.

The pad material transference occurs mostly when the pads are hot. As a
practical matter, I try to ease up on the brake pressure after coming to
a stop after heating up the brakes.

[jim beam]

On 02/15/2013 10:53 PM, dsi1 wrote:
> On 2/15/2013 5:06 PM, Joe Mastroianni wrote:
>>
>> I'm reading those papers, as you are, and they talk about hot and cold
>> judder and they speak of high and low speed judder (mostly we're talking
>> around 100Hz here so that's low speed judder).
>>
>> There's a lot of stuff about hot spots (I 'think' that's thermoelastic
>> instability) and disc thickness variation (I 'think' that's uneven
>> pad deposition) and axial runout (I think that's plane old runout).
>
> I believe that what happens is that there's some transference of pad
> material onto the iron disk at a molecular level.

dude, absolutely there's transference "at the molecular level" - you
can't have friction without it. but to be grasping at straws as if
there's some kind of ghost in the machine that can't be explained any
other way is just ridiculous.

> You can't measure it
> because we're not able to measure tolerances to that level.

nothing personal to you, but that's complete b.s.

> It does,
> however effect the frictional coefficients between the two surfaces at
> localized areas.

only in some cases, with some kinds of pads. maybe 10% at most. all
the rest is plain old mechanical misalignment coupled [literally] to
poor dynamics of an unevenly weighted caliper.

> This causes the hot spots. Well, that's my
> understanding about it anyway.

it seems this is another one of those hose flap and antifreeze
electrolysis topics - a knowledge gap into which some people feel
compelled to inject good old underinformed guessing.

>
> The pad material transference occurs mostly when the pads are hot. As a
> practical matter, I try to ease up on the brake pressure after coming to
> a stop after heating up the brakes.
>
>>
>> It will also take me a while to read them all, but I don't see anything
>> (yet) about the single piston caliper design.
>>
>>
>>
>

--
fact check required

[dsi1]

On 2/16/2013 5:29 AM, jim beam wrote:
> On 02/15/2013 10:53 PM, dsi1 wrote:
>> On 2/15/2013 5:06 PM, Joe Mastroianni wrote:
>>>
>>> I'm reading those papers, as you are, and they talk about hot and cold
>>> judder and they speak of high and low speed judder (mostly we're talking
>>> around 100Hz here so that's low speed judder).
>>>
>>> There's a lot of stuff about hot spots (I 'think' that's thermoelastic
>>> instability) and disc thickness variation (I 'think' that's uneven
>>> pad deposition) and axial runout (I think that's plane old runout).
>>
>> I believe that what happens is that there's some transference of pad
>> material onto the iron disk at a molecular level.
>
> dude, absolutely there's transference "at the molecular level" - you
> can't have friction without it. but to be grasping at straws as if
> there's some kind of ghost in the machine that can't be explained any
> other way is just ridiculous.
>
>
>> You can't measure it
>> because we're not able to measure tolerances to that level.
>
> nothing personal to you, but that's complete b.s.

I'll regret it but OK, I'll bite - how would you measure rotor runout
that's only a few molecules thick?

[jim beam]

On 02/16/2013 08:40 AM, dsi1 wrote:
> On 2/16/2013 5:29 AM, jim beam wrote:
>> On 02/15/2013 10:53 PM, dsi1 wrote:
>>> On 2/15/2013 5:06 PM, Joe Mastroianni wrote:
>>>>
>>>> I'm reading those papers, as you are, and they talk about hot and cold
>>>> judder and they speak of high and low speed judder (mostly we're
>>>> talking
>>>> around 100Hz here so that's low speed judder).
>>>>
>>>> There's a lot of stuff about hot spots (I 'think' that's thermoelastic
>>>> instability) and disc thickness variation (I 'think' that's uneven
>>>> pad deposition) and axial runout (I think that's plane old runout).
>>>
>>> I believe that what happens is that there's some transference of pad
>>> material onto the iron disk at a molecular level.
>>
>> dude, absolutely there's transference "at the molecular level" - you
>> can't have friction without it. but to be grasping at straws as if
>> there's some kind of ghost in the machine that can't be explained any
>> other way is just ridiculous.
>>
>>
>>> You can't measure it
>>> because we're not able to measure tolerances to that level.
>>
>> nothing personal to you, but that's complete b.s.
>
> I'll regret it but OK, I'll bite - how would you measure rotor runout
> that's only a few molecules thick?

there's lots of ways, but that's not the point. the point is that
runout only a few molecules thick has absolutely no effect - surface
roughness alone of the disk is many orders of magnitude larger.

>
>>
>>
>>> It does,
>>> however effect the frictional coefficients between the two surfaces at
>>> localized areas.
>>
>> only in some cases, with some kinds of pads. maybe 10% at most. all
>> the rest is plain old mechanical misalignment coupled [literally] to
>> poor dynamics of an unevenly weighted caliper.
>>
>>
>>> This causes the hot spots. Well, that's my
>>> understanding about it anyway.
>>
>> it seems this is another one of those hose flap and antifreeze
>> electrolysis topics - a knowledge gap into which some people feel
>> compelled to inject good old underinformed guessing.
>>
>>
>>>
>>> The pad material transference occurs mostly when the pads are hot. As a
>>> practical matter, I try to ease up on the brake pressure after coming to
>>> a stop after heating up the brakes.
>>>
>>>>
>>>> It will also take me a while to read them all, but I don't see anything
>>>> (yet) about the single piston caliper design.
>>>>
>>>>
>>>>
>>>
>>
>>
>

--
fact check required

[dsi1]

On 2/17/2013 5:49 AM, jim beam wrote:
> On 02/16/2013 08:40 AM, dsi1 wrote:
>>
>> I'll regret it but OK, I'll bite - how would you measure rotor runout
>> that's only a few molecules thick?
>
> there's lots of ways, but that's not the point. the point is that
> runout only a few molecules thick has absolutely no effect - surface
> roughness alone of the disk is many orders of magnitude larger.
>

If there's lots of ways, please name one of those ways. Just one. My
point is that I'm not talking about surface roughness. Just the
mechanical plating of pad material onto the cast iron surface.

[jim beam]

On 02/17/2013 10:51 AM, dsi1 wrote:
> On 2/17/2013 5:49 AM, jim beam wrote:
>> On 02/16/2013 08:40 AM, dsi1 wrote:
>>>
>>> I'll regret it but OK, I'll bite - how would you measure rotor runout
>>> that's only a few molecules thick?
>>
>> there's lots of ways, but that's not the point. the point is that
>> runout only a few molecules thick has absolutely no effect - surface
>> roughness alone of the disk is many orders of magnitude larger.
>>
>
> If there's lots of ways, please name one of those ways. Just one.

are you serious? i hope not.

> My
> point is that I'm not talking about surface roughness. Just the
> mechanical plating of pad material onto the cast iron surface.

dude, seriously, how do you think adding a "molecular layer" to a disk
surface makes the slightest difference? surface roughness is in the
order of 10 microns. that's at least 10,000 times bigger than even a
huge "molecular layer".

oh, and oem runout tolerance is ~10 times greater than that.


--
fact check required

[dsi1]

On 2/17/2013 4:32 PM, jim beam wrote:
> On 02/17/2013 10:51 AM, dsi1 wrote:
>> On 2/17/2013 5:49 AM, jim beam wrote:
>>> On 02/16/2013 08:40 AM, dsi1 wrote:
>>>>
>>>> I'll regret it but OK, I'll bite - how would you measure rotor runout
>>>> that's only a few molecules thick?
>>>
>>> there's lots of ways, but that's not the point. the point is that
>>> runout only a few molecules thick has absolutely no effect - surface
>>> roughness alone of the disk is many orders of magnitude larger.
>>>
>>
>> If there's lots of ways, please name one of those ways. Just one.
>
> are you serious? i hope not.

Oh yeah, "there's lots of ways" - none of them are serious. Nothing
personal, but you're the dude that full of bs. You don't even know what
the heck I'm talking about. Have a nice life dude.

[jim beam]

On 02/17/2013 11:54 PM, dsi1 wrote:
> On 2/17/2013 4:32 PM, jim beam wrote:
>> On 02/17/2013 10:51 AM, dsi1 wrote:
>>> On 2/17/2013 5:49 AM, jim beam wrote:
>>>> On 02/16/2013 08:40 AM, dsi1 wrote:
>>>>>
>>>>> I'll regret it but OK, I'll bite - how would you measure rotor runout
>>>>> that's only a few molecules thick?
>>>>
>>>> there's lots of ways, but that's not the point. the point is that
>>>> runout only a few molecules thick has absolutely no effect - surface
>>>> roughness alone of the disk is many orders of magnitude larger.
>>>>
>>>
>>> If there's lots of ways, please name one of those ways. Just one.
>>
>> are you serious? i hope not.
>
> Oh yeah, "there's lots of ways" - none of them are serious. Nothing
> personal, but you're the dude that full of bs. You don't even know what
> the heck I'm talking about. Have a nice life dude.

i'm glad i didn't bother! i spent years of my life measuring stuff to
microns and below, so if you think i'm going to try to educate a guy
who's clutching at "molecular layer" straws and being hostile about it
because he can't be bothered to pay attention to fact or can't be
bothered to google, you need to think again.

>
>>
>>
>>> My
>>> point is that I'm not talking about surface roughness. Just the
>>> mechanical plating of pad material onto the cast iron surface.
>>
>> dude, seriously, how do you think adding a "molecular layer" to a disk
>> surface makes the slightest difference? surface roughness is in the
>> order of 10 microns. that's at least 10,000 times bigger than even a
>> huge "molecular layer".
>>
>> oh, and oem runout tolerance is ~10 times greater than that.

just as i suspected, the relevant stuff is way over your head.


--
fact check required