2018-08-07 02:05:46 UTC
Why, for Christs' sake, can't people figure out the difference in the
English language between warp versus runout or disc thickness variation?
There has been a perennial argument since the 70's when someone got the
notion that brake rotor (aka disc) "warp" is the same as "dtv" (which it's
not), where it can't be shaken out of their heads that they are two
completely different things. Likewise with "runout".
Witness this reference posted in good faith to the home-repair group today:
Which referenced this paper:
The Effect of Residual Stress on the Distortion of Gray Iron Brake Disks
In that paper, the Asian authors *continually* appear to callously abuse
the English language by confusing the term "warp" with "disk thickness
variation (DTV)", which is completely different from warp (as in a potato).
For example, you can have a warped sheet of metal where the thickness
variation is zero, and you can have a thickness variation without warp.
If this was a high-school kid equating the two, I'd shrug it off as
ignorance; but this is an engineering paper, for heaven's sake.
Here is the first sentence where they appear to abuse the English language:
"It is known that disk warping or uneven disk thicknesses
induce pulsation during brake applications."
Clearly it is well known that "warp" (as in potato) and "uneven thickness"
are two completely different things - which means that this particular set
of Asian authors (M. W. ShinG. H. JangJ. K. KimH. Y. KimHo Jang) are likely
ignorant of what "warp" actually means - or - they simply assume that it
means something that it doesn't mean (i.e., warp and thickness variation
are completely different things - they just are).
They then compound their abuse of the English language in a sentence not
far from that last horrid sentence, saying:
"When the disk temperature is increased by friction heat during braking,
the heat often causes dimensional instability of the disk,
permanently modifying the runout or disk thickness variation (DTV)
of a disk and producing brake judder."
This sentence clearly appears to indicate the authors have no clue how to
use the English language because it's a fact that runout and DTV are also
two completely different things.
============ terms below ==============
Stop the ¡Warped¢ Rotors Myth and Service Brakes the Right Way
BTW, if you skim the paper, these two definitions may be useful:
"pig or cast iron containing much graphitic carbon which causes
its fracture to be dark gray"
"Residual stresses are stresses that remain in a solid material after
the original cause of the stresses has been removed."