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aramid fiber



 
 
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  #1  
Old February 1st 18, 04:58 AM posted to rec.bicycles.tech
Emanuel Berg[_2_]
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Posts: 1,035
Default aramid fiber

IIUC aramid fiber is when you not only use
carbon to reinforce the plastic (which is
ordinary carbon or CFRP) you also use aramid
("aromatic polyamide") which is synthetic
polymer perhaps in the nylon rope sense, and
this carbon/aramid reinforcement combination is
what makes the material "composite", and this
material has been commercialized using
para-aramid under the name Kevlar.

Anyone ever make a bike out of it?

I just saw it on a hockey stick, the
CCM RIbcore 40K. Unfathomably, they didn't put
the weight on it (the stick), but I checked it
myself and it weighs 435g, compared to my old
stick, which is wood with glass fiber on the
blade only, and that is 805g (including tape).
Also, the new stick was 1299 SEK
(1299.00 SEK ~= $164.97 | £116.13 | €132.76)
which in the hockey world isn't expensive.

So the material seems to be cheap and light
enough, perfect for bikes in other words?
BTW how much is a typical medium-level CFRP
frame in grams and dollars? We can compare the
expensive bike world with the expensive hockey
world...

--
underground experts united
http://user.it.uu.se/~embe8573
  #2  
Old February 1st 18, 03:24 PM posted to rec.bicycles.tech
AMuzi
external usenet poster
 
Posts: 13,447
Default aramid fiber

On 1/31/2018 9:58 PM, Emanuel Berg wrote:
IIUC aramid fiber is when you not only use
carbon to reinforce the plastic (which is
ordinary carbon or CFRP) you also use aramid
("aromatic polyamide") which is synthetic
polymer perhaps in the nylon rope sense, and
this carbon/aramid reinforcement combination is
what makes the material "composite", and this
material has been commercialized using
para-aramid under the name Kevlar.

Anyone ever make a bike out of it?

I just saw it on a hockey stick, the
CCM RIbcore 40K. Unfathomably, they didn't put
the weight on it (the stick), but I checked it
myself and it weighs 435g, compared to my old
stick, which is wood with glass fiber on the
blade only, and that is 805g (including tape).
Also, the new stick was 1299 SEK
(1299.00 SEK ~= $164.97 | £116.13 | €132.76)
which in the hockey world isn't expensive.

So the material seems to be cheap and light
enough, perfect for bikes in other words?
BTW how much is a typical medium-level CFRP
frame in grams and dollars? We can compare the
expensive bike world with the expensive hockey
world...


Aramid-Kevlar strands in carbon frames was a breakthrough
concept in 1986:

https://en.wikipedia.org/wiki/Kestrel_USA

better known in other products:
https://www.youtube.com/watch?v=Hyn7eKfQXPg


--
Andrew Muzi
www.yellowjersey.org/
Open every day since 1 April, 1971


  #3  
Old February 2nd 18, 02:35 AM posted to rec.bicycles.tech
John B.[_3_]
external usenet poster
 
Posts: 5,697
Default aramid fiber

On Thu, 01 Feb 2018 04:58:54 +0100, Emanuel Berg
wrote:

IIUC aramid fiber is when you not only use
carbon to reinforce the plastic (which is
ordinary carbon or CFRP) you also use aramid
("aromatic polyamide") which is synthetic
polymer perhaps in the nylon rope sense, and
this carbon/aramid reinforcement combination is
what makes the material "composite", and this
material has been commercialized using
para-aramid under the name Kevlar.

Anyone ever make a bike out of it?

I just saw it on a hockey stick, the
CCM RIbcore 40K. Unfathomably, they didn't put
the weight on it (the stick), but I checked it
myself and it weighs 435g, compared to my old
stick, which is wood with glass fiber on the
blade only, and that is 805g (including tape).
Also, the new stick was 1299 SEK
(1299.00 SEK ~= $164.97 | £116.13 | €132.76)
which in the hockey world isn't expensive.

So the material seems to be cheap and light
enough, perfect for bikes in other words?
BTW how much is a typical medium-level CFRP
frame in grams and dollars? We can compare the
expensive bike world with the expensive hockey
world...


I suspect that it may be at least partly to the loading of the device
(the direction and amount of force applied to a device). Kevlar, that
you mention has tremendous tensile strength - The specific tensile
strength (stretching or pulling strength) of both Kevlar 29 and Kevlar
49 is over eight times greater than that of steel wire. But on the
other hand it has very poor compressive strength (resistance to
squashing or squeezing). Rather difficult to design a three
dimensional device using a material that has strength in only one
direction :-)
--
Cheers,

John B.

  #4  
Old February 2nd 18, 03:19 AM posted to rec.bicycles.tech
Emanuel Berg[_2_]
external usenet poster
 
Posts: 1,035
Default aramid fiber

John B. wrote:

I suspect that it may be at least partly to
the loading of the device (the direction and
amount of force applied to a device). Kevlar,
that you mention has tremendous tensile
strength - The specific tensile strength
(stretching or pulling strength) of both
Kevlar 29 and Kevlar 49 is over eight times
greater than that of steel wire. But on the
other hand it has very poor compressive
strength (resistance to squashing or
squeezing). Rather difficult to design
a three dimensional device using a material
that has strength in only one direction :-)


Easy. Make a new composite material,
Kevlar/Kevlar, and put them perpendicular to
each other

--
underground experts united
http://user.it.uu.se/~embe8573
  #5  
Old February 2nd 18, 03:26 AM posted to rec.bicycles.tech
AMuzi
external usenet poster
 
Posts: 13,447
Default aramid fiber

On 2/1/2018 8:19 PM, Emanuel Berg wrote:
John B. wrote:

I suspect that it may be at least partly to
the loading of the device (the direction and
amount of force applied to a device). Kevlar,
that you mention has tremendous tensile
strength - The specific tensile strength
(stretching or pulling strength) of both
Kevlar 29 and Kevlar 49 is over eight times
greater than that of steel wire. But on the
other hand it has very poor compressive
strength (resistance to squashing or
squeezing). Rather difficult to design
a three dimensional device using a material
that has strength in only one direction :-)


Easy. Make a new composite material,
Kevlar/Kevlar, and put them perpendicular to
each other


Kevlar/Aramid excels in tensile strength. Maybe you should
review this:
http://www.instron.us/en-us/our-comp...s/tensile-test

but it's unremarkable in shear.

--
Andrew Muzi
www.yellowjersey.org/
Open every day since 1 April, 1971


  #6  
Old February 2nd 18, 04:09 AM posted to rec.bicycles.tech
Emanuel Berg[_2_]
external usenet poster
 
Posts: 1,035
Default aramid fiber

AMuzi wrote:

Kevlar/Aramid excels in tensile strength.
Maybe you should review this:
http://www.instron.us/en-us/our-comp...s/tensile-test


OK, seems like a lot to digest but no one said
it was supposed to be easy, right?

but it's unremarkable in shear.


One better double-check the direction of the
fibers before pulling on the bulletproof
vest

BTW I wonder if this is why it is used in
hockey sticks, skis, etc. "Hard and flex at the
same time", remember?

The hockey stick for sure cannot be pulled any
longer than its original 60 inches (~152cm) but
one can budge it on the middle leaning on it
and giving it just a small extra push.
This property in the hockey world is called,
with this instance as an example, "flex 85"
(which is pretty hard, for a strong but
medium-sized player). I'm unsure if this is
just a digit the manufacturers use or if it has
some scientific ground as well WRT
the material.

--
underground experts united
http://user.it.uu.se/~embe8573
  #7  
Old February 2nd 18, 02:32 PM posted to rec.bicycles.tech
AMuzi
external usenet poster
 
Posts: 13,447
Default aramid fiber

On 2/1/2018 9:09 PM, Emanuel Berg wrote:
AMuzi wrote:

Kevlar/Aramid excels in tensile strength.
Maybe you should review this:
http://www.instron.us/en-us/our-comp...s/tensile-test


OK, seems like a lot to digest but no one said
it was supposed to be easy, right?

but it's unremarkable in shear.


One better double-check the direction of the
fibers before pulling on the bulletproof
vest

BTW I wonder if this is why it is used in
hockey sticks, skis, etc. "Hard and flex at the
same time", remember?

The hockey stick for sure cannot be pulled any
longer than its original 60 inches (~152cm) but
one can budge it on the middle leaning on it
and giving it just a small extra push.
This property in the hockey world is called,
with this instance as an example, "flex 85"
(which is pretty hard, for a strong but
medium-sized player). I'm unsure if this is
just a digit the manufacturers use or if it has
some scientific ground as well WRT
the material.


I'm sure Frank could discuss tension and compression in a
beam better but here you go:

http://people.virginia.edu/~pjm8f/en...and_strain.htm

--
Andrew Muzi
www.yellowjersey.org/
Open every day since 1 April, 1971


  #8  
Old February 28th 18, 12:14 AM posted to rec.bicycles.tech
Emanuel Berg[_2_]
external usenet poster
 
Posts: 1,035
Default aramid fiber

I have now played a couple of games with the
"composite" stick (CFRP + Kevlar/aramid).

The weight, including tape, stopped at 490g
compared to my old wood/glass fiber which was
809g. This was certainly noticable in many
positive ways.

But in one way, the old wood stick was better
and that was its comfort! With this, new one,
it felt like every blow to it went straight
thru and into my hands and forearms - really
painful!

I suppose the fibers of wood are less straight,
or more circular (?), or something that makes
them not carry thru vibrations the same way?

Is this something one would notice with carbon
bikes as well, compared to steel frames/forks,
or do the wheels absorb most of it before it
finds its way all the way into the body?

--
underground experts united
http://user.it.uu.se/~embe8573
  #9  
Old February 28th 18, 12:34 AM posted to rec.bicycles.tech
AMuzi
external usenet poster
 
Posts: 13,447
Default aramid fiber

On 2/27/2018 5:14 PM, Emanuel Berg wrote:
I have now played a couple of games with the
"composite" stick (CFRP + Kevlar/aramid).

The weight, including tape, stopped at 490g
compared to my old wood/glass fiber which was
809g. This was certainly noticable in many
positive ways.

But in one way, the old wood stick was better
and that was its comfort! With this, new one,
it felt like every blow to it went straight
thru and into my hands and forearms - really
painful!

I suppose the fibers of wood are less straight,
or more circular (?), or something that makes
them not carry thru vibrations the same way?

Is this something one would notice with carbon
bikes as well, compared to steel frames/forks,
or do the wheels absorb most of it before it
finds its way all the way into the body?


What sort of stick? Like a police baton? Wood works pretty
well to ensure the message is received(personal experience).

--
Andrew Muzi
www.yellowjersey.org/
Open every day since 1 April, 1971


  #10  
Old February 28th 18, 02:08 PM posted to rec.bicycles.tech
Duane[_2_]
external usenet poster
 
Posts: 401
Default aramid fiber

On 27/02/2018 6:14 PM, Emanuel Berg wrote:
I have now played a couple of games with the
"composite" stick (CFRP + Kevlar/aramid).

The weight, including tape, stopped at 490g
compared to my old wood/glass fiber which was
809g. This was certainly noticable in many
positive ways.

But in one way, the old wood stick was better
and that was its comfort! With this, new one,
it felt like every blow to it went straight
thru and into my hands and forearms - really
painful!

I suppose the fibers of wood are less straight,
or more circular (?), or something that makes
them not carry thru vibrations the same way?

Is this something one would notice with carbon
bikes as well, compared to steel frames/forks,
or do the wheels absorb most of it before it
finds its way all the way into the body?


Is there any particular reason that you think the parameters for a
hockey stick would be similar to a bike?

One thing noticeable about composite hockey sticks is that they break a
lot more than wooden ones.
 




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