Carbon components and sub zero temperatures

Luke said:

This winter I'm commuting on a bike equipped with a (Winwood) CF forks.
Lately this phobia has been bubbling up from my subconcious: subzero
riding (down to -20 C) could embrittle and weaken the 'plastic' forks.

I have premonitions of asphalt face-plants. Admittedly it's a
completely unqualified anxiety, but I need reassurance. Are CF
components more vulnerable to temperature fluctations than Al or CroMo?

Luke

Dude!

C'mon, fighter jets (much CF) at 35,000 feet encounter much more severe
conditions than your fork ever will. My carbon downhill skis have
maintained their integrity for years and take more beating in one run
than your commuter fork ever will in its lifetime.

Paranoid much?

Fugedaboudit. NP!

D'ohBoy

D'ohBoy said:

Luke said:

This winter I'm commuting on a bike equipped with a (Winwood) CF forks.
Lately this phobia has been bubbling up from my subconcious: subzero
riding (down to -20 C) could embrittle and weaken the 'plastic' forks.

I have premonitions of asphalt face-plants. Admittedly it's a
completely unqualified anxiety, but I need reassurance. Are CF
components more vulnerable to temperature fluctations than Al or CroMo?

Luke

Dude!

C'mon, fighter jets (much CF) at 35,000 feet encounter much more severe
conditions than your fork ever will. My carbon downhill skis have
maintained their integrity for years and take more beating in one run
than your commuter fork ever will in its lifetime.

Not really carbon fiber in military jets...boron and other stuff but
not the stuff of your bike frame or wheels.

Quoted message said:

Paranoid much?

Fugedaboudit. NP!

D'ohBoy

D'ohBoy said:

Luke said:

This winter I'm commuting on a bike equipped with a (Winwood) CF forks.
Lately this phobia has been bubbling up from my subconcious: subzero
riding (down to -20 C) could embrittle and weaken the 'plastic' forks.

I have premonitions of asphalt face-plants. Admittedly it's a
completely unqualified anxiety, but I need reassurance. Are CF
components more vulnerable to temperature fluctations than Al or CroMo?

Luke

Dude!

C'mon, fighter jets (much CF) at 35,000 feet encounter much more severe
conditions than your fork ever will. My carbon downhill skis have
maintained their integrity for years and take more beating in one run
than your commuter fork ever will in its lifetime.

Not really carbon fiber in military jets...boron and other stuff but
not the stuff of your bike frame or wheels.

Quoted message said:

Paranoid much?

Fugedaboudit. NP!

D'ohBoy

On Wed, 01 Nov 2006 15:26:20 -0500, Luke <[email hidden]>

Quoted message said:

This winter I'm commuting on a bike equipped with a (Winwood) CF forks.
Lately this phobia has been bubbling up from my subconcious: subzero
riding (down to -20 C) could embrittle and weaken the 'plastic' forks.

I don't know about bike parts, but I've skied at colder temperatures
than that with carbon fiber ski poles. Lots of people do. No
problems with them related to cold.
--
JT
****************************
Remove "remove" to reply
Visit http://www.jt10000.com
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John Forrest Tomlinson said:

On Wed, 01 Nov 2006 15:26:20 -0500, Luke <[email hidden]>

Quoted message said:

This winter I'm commuting on a bike equipped with a (Winwood) CF forks.
Lately this phobia has been bubbling up from my subconcious: subzero
riding (down to -20 C) could embrittle and weaken the 'plastic' forks.

I don't know about bike parts, but I've skied at colder temperatures
than that with carbon fiber ski poles. Lots of people do. No
problems with them related to cold.
--

Agree, I'm not sure what the OP is concerned about, but HEAT, not cold,
would be a bigger enemy for a carbon fork.

Actually, if you want to be phobic about "plastic" forks, the biggest
concern is crashing. Impact resistance is not carbon's "forte."

On Wed, 01 Nov 2006 15:26:20 -0500, Luke <[email hidden]>

Quoted message said:

This winter I'm commuting on a bike equipped with a (Winwood) CF forks.
Lately this phobia has been bubbling up from my subconcious: subzero
riding (down to -20 C) could embrittle and weaken the 'plastic' forks.

I have premonitions of asphalt face-plants. Admittedly it's a
completely unqualified anxiety, but I need reassurance. Are CF
components more vulnerable to temperature fluctations than Al or CroMo?

Didn't I read about Iditabike competitors having problems with
embrittlement of aluminium alloy components? Anyway, a quick google
reveals much more data on low temperature embrittlement of steel,
particularly low-alloy steels like your common CroMo, so there doesn't
seem to be cause to worry less about steel than carbon fibre. You're
probably in more danger from falling on the ice than any temperature
induced structural problems.

Kinky Cowboy*

*Batteries not included
May contain traces of nuts
Your milage may vary

Luke said:

This winter I'm commuting on a bike equipped with a (Winwood) CF forks.
Lately this phobia has been bubbling up from my subconcious: subzero
riding (down to -20 C) could embrittle and weaken the 'plastic' forks.

I have premonitions of asphalt face-plants. Admittedly it's a
completely unqualified anxiety, but I need reassurance. Are CF
components more vulnerable to temperature fluctations than Al or CroMo?

Lots of bikes are ridden many miles in very cold temperatures. I have yet
to see someone claim that their carbon component failed because of it.

In addition, many airplanes have carbon parts, and every time they fly,
they are exposed to very cold temperatures.

--

David L. Johnson

__o | Deserves death! I daresay he does. Many that live deserve
_`\(,_ | death. And some that die deserve life. Can you give it to
(_)/ (_) | them? Then do not be too eager to deal out death in judgement.
-- J. R. R. Tolkein

Luke said:

This winter I'm commuting on a bike equipped with a (Winwood) CF forks.
Lately this phobia has been bubbling up from my subconcious: subzero
riding (down to -20 C) could embrittle and weaken the 'plastic' forks.

I have premonitions of asphalt face-plants. Admittedly it's a
completely unqualified anxiety, but I need reassurance. Are CF
components more vulnerable to temperature fluctations than Al or CroMo?

What is the glass transition temperature of the thermoset polymer
matrix used in the carbon fiber composite?

--
Tom Sherman - Here, not there.

"Qui si parla Campagnolo" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

D'ohBoy said:

Luke said:

This winter I'm commuting on a bike equipped with a (Winwood) CF

forks.

Quoted message said:

Quoted message said:

Quoted message said:

Lately this phobia has been bubbling up from my subconcious:

subzero

Quoted message said:

Quoted message said:

Quoted message said:

riding (down to -20 C) could embrittle and weaken the 'plastic'

forks.

Quoted message said:

Quoted message said:

Quoted message said:

I have premonitions of asphalt face-plants. Admittedly it's a
completely unqualified anxiety, but I need reassurance. Are CF
components more vulnerable to temperature fluctations than Al or

CroMo?

Quoted message said:

Quoted message said:

Quoted message said:

Luke

Dude!

C'mon, fighter jets (much CF) at 35,000 feet encounter much more

severe

Quoted message said:

Quoted message said:

conditions than your fork ever will. My carbon downhill skis have
maintained their integrity for years and take more beating in one

run

Quoted message said:

Quoted message said:

than your commuter fork ever will in its lifetime.

Not really carbon fiber in military jets...boron and other stuff but
not the stuff of your bike frame or wheels.

Nope! Carbon fiber composites are very common in aerospace applications.
A lot of other types of composites are also used. Some of them like
honeycomb reinforcements made of aramid (Kevlar) fibers are used in
layers in conjunction with carbon fiber composites for aircraft panels.

Chas.

Qui si parla Campagnolo said:

D'ohBoy said:

Luke said:

This winter I'm commuting on a bike equipped with a (Winwood) CF forks.
Lately this phobia has been bubbling up from my subconcious: subzero
riding (down to -20 C) could embrittle and weaken the 'plastic' forks.

I have premonitions of asphalt face-plants. Admittedly it's a
completely unqualified anxiety, but I need reassurance. Are CF
components more vulnerable to temperature fluctations than Al or CroMo?

Luke

Dude!

C'mon, fighter jets (much CF) at 35,000 feet encounter much more severe
conditions than your fork ever will. My carbon downhill skis have
maintained their integrity for years and take more beating in one run
than your commuter fork ever will in its lifetime.

Not really carbon fiber in military jets...boron and other stuff but
not the stuff of your bike frame or wheels.

Quoted message said:

years ago I worked Quality Control for an aerospace firm, we did a LOT
of CF for military and civilian applications.

(a nod to the above poster)My downhill skis are Head Radial Carbon and
they are about 25 years old.

in the early '90s you could still hear bike "Gurus" warn people not to
ride Aluminum in the winter because it would get brittle and shatter
like glass.

Qui si parla Campagnolo said:

D'ohBoy wrote:

Quoted message said:

Quoted message said:

C'mon, fighter jets (much CF) at 35,000 feet encounter much more severe
conditions than your fork ever will. My carbon downhill skis have
maintained their integrity for years and take more beating in one run
than your commuter fork ever will in its lifetime.

Quoted message said:

Not really carbon fiber in military jets...boron and other stuff but not
the stuff of your bike frame or wheels.

Um, yes it is, and in many other aircraft too -- from personal aircraft to
business jets to the latest airliners, to Rutan's Spaceship One.

Matt O.

* * Chas said:

Nope! Carbon fiber composites are very common in aerospace applications.
A lot of other types of composites are also used. Some of them like
honeycomb reinforcements made of aramid (Kevlar) fibers are used in
layers in conjunction with carbon fiber composites for aircraft panels.

Most if not all military jets are simply too old models to have much CF in
it. Eurofighter and JSF, maybe. An F-14 or F-16, I doubt it.

Jasper

Jasper Janssen said:

* * Chas said:

Nope! Carbon fiber composites are very common in aerospace applications.
A lot of other types of composites are also used. Some of them like
honeycomb reinforcements made of aramid (Kevlar) fibers are used in
layers in conjunction with carbon fiber composites for aircraft panels.

Most if not all military jets are simply too old models to have much CF in
it. Eurofighter and JSF, maybe. An F-14 or F-16, I doubt it.

Jasper

Here is a list..
A through L
http://cio.energy.gov/documents/RM06-27-Attachment1.pdf
M through Z
http://cio.energy.gov/documents/RM06-27-Attachment2.pdf

In article <[email hidden]>,

Matt O'Toole said:

Um, yes it is, and in many other aircraft too -- from personal aircraft to
business jets to the latest airliners, to Rutan's Spaceship One.

And some of them CFs do fail and fall out of the sky.
--

Johnny Sunset aka Tom Sherman said:

Luke said:

This winter I'm commuting on a bike equipped with a (Winwood) CF forks.
Lately this phobia has been bubbling up from my subconcious: subzero
riding (down to -20 C) could embrittle and weaken the 'plastic' forks.

I have premonitions of asphalt face-plants. Admittedly it's a
completely unqualified anxiety, but I need reassurance. Are CF
components more vulnerable to temperature fluctations than Al or CroMo?

What is the glass transition temperature of the thermoset polymer
matrix used in the carbon fiber composite?

If it is a 250 cure resin, the Tg is about in that range. Glass
transition is close to the cure temperature. That is the purpose of
higher cures--to push up the Tg. Curing at low temps leads to
vitirfication before full cure, which is what causes the Tg to be low.
Higher temps keeps the resin liquid longer (lowr viscosity) so that the
state of cure at vitrification is more complete.

Room temperature cured polyesters etc are Tg around 120F. That is why
dark colored boats show their fibre patterns more than white ones. The
sun heats the skin above the Tg, the resin cures some more as it
becomes mobile enough for chains to react, and then in so doing it
shrinks and leaves the pattern of the reinforcement.

Luke said:

This winter I'm commuting on a bike equipped with a (Winwood) CF forks.
Lately this phobia has been bubbling up from my subconcious: subzero
riding (down to -20 C) could embrittle and weaken the 'plastic' forks.

I have premonitions of asphalt face-plants. Admittedly it's a
completely unqualified anxiety, but I need reassurance. Are CF
components more vulnerable to temperature fluctations than Al or CroMo?

This is a very good question and with the exception of the one reply
about steels, nobody has given you any useful information.

In fact, composites become stronger as they get colder. The toughness
may or may not reduce, but not by much. Toughness can even increase,
depending on the resin used.

The plastic resin (which is what the composite mostly is) is brittle at
room temperature. It only becomes somewhat soft at a temperature
approaching its decomposition temperagture, but because it is fully
"cross-linked" it is still brittle at high temperatures, too.

Basically, outside of residual stress effects, cold is not a problem
for composites.

Residual stress:

When you cure a composite at an elevated temperature, the reinforcement
will be a different size than at room temperature. As the part cures,
the shrinkage of the resin and the fibers are different. These residual
stresses are significant and can be a problem in a poorly designed
part. However, take a 250 degree cure resin system as an example. The
change in stress from 70 degrees to zero is a small fraction of the
change from 250 to 70. Carbon Fiber is especially vexing from a
residual stress standpoint, as the fibers actuall shrink lengthwise
while expanding through their thickness, with increasing temperature.
An unbalanced laminate cured at an elevated temperature will actually
warp markedly on cooling, due to the lengthening of the carbon fibres.

Now, what happens with the residual stresses is the cration of
microcracks in the resin matrix and or separation of the resin from the
fibres. Depending on the nature of this cracking, the damage may be
stable or unstable from a structural standpoint. A few years ago this
was a hot area of research. I haven't checked in 5 years so maybe it is
all figured out (I doubt it).

On the topic of Aluminum Embrittlement:

In fact Aluminum does not embrittle with colder temperatures. Rather,
it gets tougher. Aluminum has a Face Centered Cubic crystal structure,
as des Austenitic stainless steel (example: 316, 304, 18-8, 17-7 PH),
These materials, due to the crystal structure, are the best choice for
cryogenic applications. (400 series stainless is known as ferritic and
has a BCC structure--see below). Any vehicle which carries a chilled
liquid--LPG, LNG (the latter is verrrrry cold) Nitrogen, LOX, Helium,
will be made of either Aluminum or Austenitic Stainless.

On the other hand, the Body Centered Cubic (BCC) crystal structure is
sensitive to cold. This is the crystal structure of most steel (alloy
and carbon steels). There is a Ductile to Brittle Transition
temperature (DBTT) which is a temperature range over which the
toughness (measured in energy) will reduce by a factor of 10 or more!
All BCC steels have this trait, though the temperature at which it
occurs is dependent on the microstructure. Higher carbon content
increases this markedly, and so axles etc are more likely to fail due
to shock at low temps.

Titanium, which has a Hexagonal Close Packed (HCP) structure is also
sensitive to the DBTT phenomenon in the same way as steel. Both HCP and
BCC structures show this trait. Anecdotally, early Campagnolo Super
Record titanium crank spindles failed in winter training. This happened
to someone I knew back in 1980 or thereabouts.

"Jasper Janssen" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

* * Chas said:

Nope! Carbon fiber composites are very common in aerospace

applications.

Quoted message said:

Quoted message said:

A lot of other types of composites are also used. Some of them like
honeycomb reinforcements made of aramid (Kevlar) fibers are used in
layers in conjunction with carbon fiber composites for aircraft

panels.

Quoted message said:

Most if not all military jets are simply too old models to have much

CF in

Quoted message said:

it. Eurofighter and JSF, maybe. An F-14 or F-16, I doubt it.

Jasper

F-18 has a lot of CF and the F-117 is mostly CF. Carbon fiber composites
have been in use in aerospace since the mid 1970's.

Chas.

"Artoi" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

In article <[email hidden]>,

Matt O'Toole said:

Um, yes it is, and in many other aircraft too -- from personal

aircraft to

Quoted message said:

Quoted message said:

business jets to the latest airliners, to Rutan's Spaceship One.

And some of them CFs do fail and fall out of the sky.
--

There have been a number of Airbus crashes due to CF failures in their
tails.

http://whyfiles.org/145composite_materials/2.html

In article <[email hidden]>,

* * Chas said:

"Artoi" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

In article <[email hidden]>,

Matt O'Toole said:

Um, yes it is, and in many other aircraft too -- from personal

aircraft to

Quoted message said:

Quoted message said:

business jets to the latest airliners, to Rutan's Spaceship One.

And some of them CFs do fail and fall out of the sky.
--

There have been a number of Airbus crashes due to CF failures in their
tails.

http://whyfiles.org/145composite_materials/2.html

Learning by trial and error... 🙁
--