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editorial opinion, steel frames



 
 
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  #61  
Old May 26th 17, 03:09 PM posted to rec.bicycles.tech
[email protected]
external usenet poster
 
Posts: 3,345
Default editorial opinion, steel frames

On Thursday, May 25, 2017 at 5:50:17 PM UTC-7, John B. wrote:
On Thu, 25 May 2017 07:07:18 -0700 (PDT), wrote:

On Thursday, May 25, 2017 at 12:28:55 AM UTC-7, John B. wrote:

Interesting. Of course there is some dissension.

"Carbon composites and manufacturing methods have evolved considerably
since the mid-'80'ss and independent testing has consistently
demonstrated superior fatigue resistance for the material. "The
fatigue tests that we run here are almost a matter of going through
the motions", said Chuck Texiera, a senior engineer at Specialized.
"We just about never see a failure or fatigue. Once you hit expected
ultimate strength, the fatigue is like a gimme. If you subjected any
type of metal frame, including titanium, to the same total cycles,
typically they would not withstand it."

When I put the question of the life span of a carbon bike to Benoit
Grelier, the person in charge of Scott's bicycle engineering, his
answer was clear, "I think it can last your life, actually."

Scott Nielson has worked with carbon fibre for over a decade, starting
with Trek, and is now the vice president of research and development
and engineering at Enve. 'If you look at carbon materials in general",
he said, "they're very good in fatigue, much better than any aluminum
or steel would be. If done properly, a frame could last you forever."


CF is being used because they can make frames and forks lighter. As I said, I have myself seen so many cracks in CF frames that I simply don't trust the material.

I wrote to the UCI because they were talking about dropping the weight limit altogether and suggested that if they take off the 16 lb limit (they presently have) that they will see 10 lb bikes and that the man-on-the-street will be buying them. And that injuries from those sorts of bikes breaking will rapidly give bicycling such a bad name that their audience will turn away just as the doping scandals took away about 20% of their audience.

The letter I got in return said something to the effect that a 10 lb bike might be stronger than a 16 lb bike. So I would expect to shortly see the weight limit completely removed.

What was clear from the data on both the CG patrol boat and the submarine fairwater is that the resins continued to harden with age. The sheer strength dropped 6% between 10 years and 20 years.

The cycling curve showed a FAR more disturbing set of numbers though - more than a 50% loss of strength with increasing flex.

I would guess without any further data that it is just as I've been saying - the failures of these frames are from the resins turning to powder from the continuous vibrations which acts on these light frames as the bending stresses do on those old tests.


You seem to have some sort of fetish about resins. Here is an excerpt
from the conclusions taken from a study, dated 2011, of epoxy resins
as used in bicycle frames:

Physical Aging of Epoxy Polymers and Their Composites
G.M. Odegard and A. Bandyopadhyay
Department of Mechanical Engineering - Engineering Mechanics
Michigan Technological University
1400 Townsend Drive
Houghton, MI 49931, USA

The primary structural application of epoxies is in fiber-reinforced
composites. The long fiber geometry provides for an exceptional amount
of load transfer from the relatively brittle epoxy
matrix to the stiff and strong reinforcement. Because it is imperative
that this load transfer be maintained during the service life of a
composite component, there is considerable interest in
physical aging of these materials. Several studies have been conducted
on the physical aging of fiberous epoxy composites. In general, these
studies indicate that the composite material response to physical
aging is very similar to the corresponding response of neat epoxy
resin. The presence of glass or carbon fibers has little influence on
the physical aging characteristics. It is also clear that physical
aging has little influence on the strength of the fiber/epoxy
interface, which indicates that physical aging does not alter the
load-transfer characteristics of fiber-reinforced composites.


Isn't that what I was saying? The aging of the resin has to do with it's loading. First you have to have complete and total saturation - any bubbles in the lay-up are a source of spot failure. But given that and the fact that CF bicycles are built for light weight - the failure of these resins are constructed into the lay-up.

I would say that these light weight bikes are going to age very rapidly because the forces on the resins will cause degradation.

This isn't simply a case of being overly cautious since the effects can be fatal. It's only being smart.
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  #62  
Old May 27th 17, 01:50 AM posted to rec.bicycles.tech
John B.[_3_]
external usenet poster
 
Posts: 5,697
Default editorial opinion, steel frames

On Fri, 26 May 2017 07:09:20 -0700 (PDT), wrote:

On Thursday, May 25, 2017 at 5:50:17 PM UTC-7, John B. wrote:
On Thu, 25 May 2017 07:07:18 -0700 (PDT),
wrote:

On Thursday, May 25, 2017 at 12:28:55 AM UTC-7, John B. wrote:

Interesting. Of course there is some dissension.

"Carbon composites and manufacturing methods have evolved considerably
since the mid-'80'ss and independent testing has consistently
demonstrated superior fatigue resistance for the material. "The
fatigue tests that we run here are almost a matter of going through
the motions", said Chuck Texiera, a senior engineer at Specialized.
"We just about never see a failure or fatigue. Once you hit expected
ultimate strength, the fatigue is like a gimme. If you subjected any
type of metal frame, including titanium, to the same total cycles,
typically they would not withstand it."

When I put the question of the life span of a carbon bike to Benoit
Grelier, the person in charge of Scott's bicycle engineering, his
answer was clear, "I think it can last your life, actually."

Scott Nielson has worked with carbon fibre for over a decade, starting
with Trek, and is now the vice president of research and development
and engineering at Enve. 'If you look at carbon materials in general",
he said, "they're very good in fatigue, much better than any aluminum
or steel would be. If done properly, a frame could last you forever."

CF is being used because they can make frames and forks lighter. As I said, I have myself seen so many cracks in CF frames that I simply don't trust the material.

I wrote to the UCI because they were talking about dropping the weight limit altogether and suggested that if they take off the 16 lb limit (they presently have) that they will see 10 lb bikes and that the man-on-the-street will be buying them. And that injuries from those sorts of bikes breaking will rapidly give bicycling such a bad name that their audience will turn away just as the doping scandals took away about 20% of their audience.

The letter I got in return said something to the effect that a 10 lb bike might be stronger than a 16 lb bike. So I would expect to shortly see the weight limit completely removed.

What was clear from the data on both the CG patrol boat and the submarine fairwater is that the resins continued to harden with age. The sheer strength dropped 6% between 10 years and 20 years.

The cycling curve showed a FAR more disturbing set of numbers though - more than a 50% loss of strength with increasing flex.

I would guess without any further data that it is just as I've been saying - the failures of these frames are from the resins turning to powder from the continuous vibrations which acts on these light frames as the bending stresses do on those old tests.


You seem to have some sort of fetish about resins. Here is an excerpt
from the conclusions taken from a study, dated 2011, of epoxy resins
as used in bicycle frames:

Physical Aging of Epoxy Polymers and Their Composites
G.M. Odegard and A. Bandyopadhyay
Department of Mechanical Engineering - Engineering Mechanics
Michigan Technological University
1400 Townsend Drive
Houghton, MI 49931, USA

The primary structural application of epoxies is in fiber-reinforced
composites. The long fiber geometry provides for an exceptional amount
of load transfer from the relatively brittle epoxy
matrix to the stiff and strong reinforcement. Because it is imperative
that this load transfer be maintained during the service life of a
composite component, there is considerable interest in
physical aging of these materials. Several studies have been conducted
on the physical aging of fiberous epoxy composites. In general, these
studies indicate that the composite material response to physical
aging is very similar to the corresponding response of neat epoxy
resin. The presence of glass or carbon fibers has little influence on
the physical aging characteristics. It is also clear that physical
aging has little influence on the strength of the fiber/epoxy
interface, which indicates that physical aging does not alter the
load-transfer characteristics of fiber-reinforced composites.


Isn't that what I was saying? The aging of the resin has to do with it's loading. First you have to have complete and total saturation - any bubbles in the lay-up are a source of spot failure. But given that and the fact that CF bicycles are built for light weight - the failure of these resins are constructed into the lay-up.


Well, this is a change. First you said "ageing" which is usually
indicative of some period of time passing. Now you are saying that it
is a factor of loading.

Unfortunately this doesn't seem to be true either.
An article published in the IOP journal:

IOP Conf. Series: Materials Science and Engineering 115 (2016) 012017
doi:10.1088/1757-899X/115/1/012017
Effect of loading rate on tensile properties and failure
behavior of glass fibre/epoxy composite
K K Mahato*, M Biswal, D K Rathore, R K Prusty, K Dutta, B C Ray
Composite Materials Group, Metallurgical and Materials Engineering
Department, National Institute of Technology, Rourkela-769008, India

4. Conclusions
The investigation on the effect of tensile properties and failure
behavior of glass/epoxy composite comprises the following conclusions

The glass/epoxy composite is found to be loading rate sensitive. As
the loading rate increases the ultimate tensile strength of the
composite is also increasing.

The tensile modulus of the composite is found to be loading rate
in-sensitive.

The strain to failure of the glass/epoxy composite is also increasing
as the loading rate increases.

As for "First you have to have complete and total saturation - any
bubbles in the lay-up are a source of spot failure. But given that and
the fact that CF bicycles are built for light weight - the failure of
these resins are constructed into the lay-up."

It is quite obvious that you don't know what you are talking about as
to the best of my knowledge modern C.F. bicycles are built using molds
and pressure which precludes bubbles in the lay up and areas of resin
starvation.

I would say that these light weight bikes are going to age very rapidly because the forces on the resins will cause degradation.
This isn't simply a case of being overly cautious since the effects can be fatal. It's only being smart.


To be frank it is obvious that either you simply don't know what you
are talking about or that you have access to some obscure data about
composites that isn't available to others so in order to provide some
rationality to this discussion I suggest that you provide references
to support your assertions.
--
Cheers,

John B.

  #63  
Old May 27th 17, 03:09 PM posted to rec.bicycles.tech
[email protected]
external usenet poster
 
Posts: 3,345
Default editorial opinion, steel frames

On Friday, May 26, 2017 at 5:50:55 PM UTC-7, John B. wrote:
On Fri, 26 May 2017 07:09:20 -0700 (PDT), wrote:

On Thursday, May 25, 2017 at 5:50:17 PM UTC-7, John B. wrote:
On Thu, 25 May 2017 07:07:18 -0700 (PDT),
wrote:

On Thursday, May 25, 2017 at 12:28:55 AM UTC-7, John B. wrote:

Interesting. Of course there is some dissension.

"Carbon composites and manufacturing methods have evolved considerably
since the mid-'80'ss and independent testing has consistently
demonstrated superior fatigue resistance for the material. "The
fatigue tests that we run here are almost a matter of going through
the motions", said Chuck Texiera, a senior engineer at Specialized.
"We just about never see a failure or fatigue. Once you hit expected
ultimate strength, the fatigue is like a gimme. If you subjected any
type of metal frame, including titanium, to the same total cycles,
typically they would not withstand it."

When I put the question of the life span of a carbon bike to Benoit
Grelier, the person in charge of Scott's bicycle engineering, his
answer was clear, "I think it can last your life, actually."

Scott Nielson has worked with carbon fibre for over a decade, starting
with Trek, and is now the vice president of research and development
and engineering at Enve. 'If you look at carbon materials in general",
he said, "they're very good in fatigue, much better than any aluminum
or steel would be. If done properly, a frame could last you forever.."

CF is being used because they can make frames and forks lighter. As I said, I have myself seen so many cracks in CF frames that I simply don't trust the material.

I wrote to the UCI because they were talking about dropping the weight limit altogether and suggested that if they take off the 16 lb limit (they presently have) that they will see 10 lb bikes and that the man-on-the-street will be buying them. And that injuries from those sorts of bikes breaking will rapidly give bicycling such a bad name that their audience will turn away just as the doping scandals took away about 20% of their audience.

The letter I got in return said something to the effect that a 10 lb bike might be stronger than a 16 lb bike. So I would expect to shortly see the weight limit completely removed.

What was clear from the data on both the CG patrol boat and the submarine fairwater is that the resins continued to harden with age. The sheer strength dropped 6% between 10 years and 20 years.

The cycling curve showed a FAR more disturbing set of numbers though - more than a 50% loss of strength with increasing flex.

I would guess without any further data that it is just as I've been saying - the failures of these frames are from the resins turning to powder from the continuous vibrations which acts on these light frames as the bending stresses do on those old tests.

You seem to have some sort of fetish about resins. Here is an excerpt
from the conclusions taken from a study, dated 2011, of epoxy resins
as used in bicycle frames:

Physical Aging of Epoxy Polymers and Their Composites
G.M. Odegard and A. Bandyopadhyay
Department of Mechanical Engineering - Engineering Mechanics
Michigan Technological University
1400 Townsend Drive
Houghton, MI 49931, USA

The primary structural application of epoxies is in fiber-reinforced
composites. The long fiber geometry provides for an exceptional amount
of load transfer from the relatively brittle epoxy
matrix to the stiff and strong reinforcement. Because it is imperative
that this load transfer be maintained during the service life of a
composite component, there is considerable interest in
physical aging of these materials. Several studies have been conducted
on the physical aging of fiberous epoxy composites. In general, these
studies indicate that the composite material response to physical
aging is very similar to the corresponding response of neat epoxy
resin. The presence of glass or carbon fibers has little influence on
the physical aging characteristics. It is also clear that physical
aging has little influence on the strength of the fiber/epoxy
interface, which indicates that physical aging does not alter the
load-transfer characteristics of fiber-reinforced composites.


Isn't that what I was saying? The aging of the resin has to do with it's loading. First you have to have complete and total saturation - any bubbles in the lay-up are a source of spot failure. But given that and the fact that CF bicycles are built for light weight - the failure of these resins are constructed into the lay-up.


Well, this is a change. First you said "ageing" which is usually
indicative of some period of time passing. Now you are saying that it
is a factor of loading.

Unfortunately this doesn't seem to be true either.
An article published in the IOP journal:

IOP Conf. Series: Materials Science and Engineering 115 (2016) 012017
doi:10.1088/1757-899X/115/1/012017
Effect of loading rate on tensile properties and failure
behavior of glass fibre/epoxy composite
K K Mahato*, M Biswal, D K Rathore, R K Prusty, K Dutta, B C Ray
Composite Materials Group, Metallurgical and Materials Engineering
Department, National Institute of Technology, Rourkela-769008, India

4. Conclusions
The investigation on the effect of tensile properties and failure
behavior of glass/epoxy composite comprises the following conclusions

The glass/epoxy composite is found to be loading rate sensitive. As
the loading rate increases the ultimate tensile strength of the
composite is also increasing.

The tensile modulus of the composite is found to be loading rate
in-sensitive.

The strain to failure of the glass/epoxy composite is also increasing
as the loading rate increases.

As for "First you have to have complete and total saturation - any
bubbles in the lay-up are a source of spot failure. But given that and
the fact that CF bicycles are built for light weight - the failure of
these resins are constructed into the lay-up."

It is quite obvious that you don't know what you are talking about as
to the best of my knowledge modern C.F. bicycles are built using molds
and pressure which precludes bubbles in the lay up and areas of resin
starvation.

I would say that these light weight bikes are going to age very rapidly because the forces on the resins will cause degradation.
This isn't simply a case of being overly cautious since the effects can be fatal. It's only being smart.


To be frank it is obvious that either you simply don't know what you
are talking about or that you have access to some obscure data about
composites that isn't available to others so in order to provide some
rationality to this discussion I suggest that you provide references
to support your assertions.


Fatigue degradation can just as easily be referred to as aging. The degradation in the failure of my fork which I still have is plain. It wasn't a failure in the cloth because as soon as the crack hit and area of resin that wasn't worked as much it halted. Unfortunately that crack was enough to allow the wheel to twist in a turn.

Today this section of the forks is generally constructed much stronger. But the other areas which are more critical are being made thinner. Do you want a top tube failing? There are plenty of pictures of failed top tubes and they are in the areas of highest fatigue. Since the carbon fiber will not fatigue exactly what do you think is occurring?

 




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