Re: more cfrp bleating

jim beam said:

Peter Cole said:

jim beam wrote:

<snip usual wriggle and squirm>

Whatever.

Quoted message said:

Quoted message said:

Quoted message said:

the "brittle" argument is [censored] if you don't understand the
failure mode - cfrp does not shatter like glass.

No, it shatters like CFRP, which is different than fiberglass or
Kevlar-epoxy composites and certainly very different than aluminum.

it doesn't shatter. we've just seen a thread on that where a fork was
ripped through the head tube. it's evident from the fracture that
failure was gradual and energetic. but you wouldn't admit that since
you don't understand that lack of ductility doesn't mean lack of
toughness. unless there's some defect, cfrp fails just like wood -
piece by piece, and with significant energy absorption.

Brittle failure is a well known characteristic of CF composites. That
said, it is possible to design energy absorbent *structures* with CF
composites. Such structures usually rely on the tearing of fibers from
the composite rather than simple fiber tensile failure. I posted an
example of this in the Audi design for a tubular crash structure. The
example of the steerer tube tearing through the head tube is similar,
but not representative of a more typical failure (in bicycles) of a
tubular beam failing in bending.

In the case of CF composites, lack of ductility does mean lack of
toughness -- by definition. You continue to confuse force and energy.

Quoted message said:

Quoted message said:

Quoted message said:

what? peter cole [censored] on something he doesn't know about? surely
that would never happen!

Whatever.

Quoted message said:

Quoted message said:

You forget, it was the Boeing guy (and anyone else you care to
consult) who used the term.

er, you mean the guy using emotive language designed to stir up
controversy. "brittle" to most lay persons means that something
shatters like glass. this is /not/ the case with this material.

"Brittle" is a term commonly used to describe CF-epoxy composites by
experts in the field. Lack of "toughness" is another.

Quoted message said:

Quoted message said:

Quoted message said:

>> and apparently succeeding if the ridiculous bleating on r.b.t is a
>> gauge.
>
> Nothing in common, actually. The Boeing engineer's primary charge is
> that the testing protocols are insufficient for the new technology.

the "new" 30 year old technology that's been used in mil aps that
whole time. and it's especially ironic given that planes were made
of wood, that natural composite.
http://en.wikipedia.org/wiki/Hughes_H-4_Hercules
http://www.warbirdalley.com/mossie.htm

Quoted message said:

what? ignore facts? peter cole would never do that!

What "facts"? The problem is safety, specifically crashworthiness.

ah, the peter cole ethereal undefined [censored]. just like "impact".

so how much "crashworthiness" does a plane need peter? nose in at
700kts? would that be reasonable?

Boeing tested a fuselage section per existing FAA requirements and
claimed that those tests validated their computer models. The Boeing
employee claims that the tests, which were designed to certify metallic
fuselages, are not sufficient. I think he has a case.

Quoted message said:

undefined emotive sensationalism is so much [censored]. especially from a guy
that calls himself an "engineer".

Quoted message said:

The Boeing engineer argues that the new material in a fuselage
application requires more testing to qualify it. His opinion is that
the design would fail such tests.

but boeing have tested to industry standards. what more do you want?
undefined "impact" testing?

The Boeing engineer said he wanted a fully loaded, full fuselage section
at 30 fps. He would also like to see fire resistance added to the test.

Quoted message said:

Quoted message said:

Quoted message said:

>> still, as part of the old saying goes, "you can fool some people
>> all of the time", and thus it is proved.
>
> Nothing is "proved". You don't even have the facts straight.

typical peter cole. cherry pick the points you want to argue and
ignore the others that make them a crock.

You didn't (as usual) address the points I raised.

Quoted message said:

Quoted message said:

I address every point you raise.

no you don't!!! what about the long and successful history of
composites in a/c over the decades. since the dawn of flight in fact.
you just routinely ignore anything inconvenient, then proceed as if
nothing is wrong.

Yeah, OK, wood was used first. I am aware of that, I've toured the
spruce goose, my dad was flown into London on a mosquito during the war.
I've worked on various boat hulls, wood plank, molded plywood, glassed
plywood, and plain glass. I'm very aware of the relative qualities.

The specific topic is crashworthiness of composite fuselages. This is a
new application.

Quoted message said:

that's [censored].

Whatever.

Quoted message said:

Quoted message said:

You should return the courtesy -- but I suppose that's an oxymoron.

yeah, and the day you don't [censored] is the one i'm waiting for too.

Whatever.

Quoted message said:

Quoted message said:

Quoted message said:

you're a bullshitter.

Whatever.

but you are.

Whatever.

Peter Cole said:

jim beam said:

Peter Cole said:

jim beam wrote:

<snip usual wriggle and squirm>

Whatever.

Quoted message said:

Quoted message said:

> the "brittle" argument is [censored] if you don't understand the
> failure mode - cfrp does not shatter like glass.

No, it shatters like CFRP, which is different than fiberglass or
Kevlar-epoxy composites and certainly very different than aluminum.

it doesn't shatter. we've just seen a thread on that where a fork was
ripped through the head tube. it's evident from the fracture that
failure was gradual and energetic. but you wouldn't admit that since
you don't understand that lack of ductility doesn't mean lack of
toughness. unless there's some defect, cfrp fails just like wood -
piece by piece, and with significant energy absorption.

Brittle failure is a well known characteristic of CF composites.

what? that it shatters like glass??? [censored].

Quoted message said:

That
said, it is possible to design energy absorbent *structures* with CF
composites. Such structures usually rely on the tearing of fibers from
the composite rather than simple fiber tensile failure. I posted an
example of this in the Audi design for a tubular crash structure. The
example of the steerer tube tearing through the head tube is similar,

which contradicts your earlier statement. which one do you want peter?
you can't have it both ways.

Quoted message said:

but not representative of a more typical failure (in bicycles) of a
tubular beam failing in bending.

[censored]. you have no experience with this material and have never
tried to make any cfrp bike componentry fail or you'd never be able to
make that statement. not without /knowing/ yourself to be a bullshitter
at any rate.

Quoted message said:

In the case of CF composites, lack of ductility does mean lack of
toughness -- by definition.

finally, the truth starts to dawn...

Quoted message said:

You continue to confuse force and energy.

er, no. you're the one with the fundamental concept problem.

Quoted message said:

Quoted message said:

Quoted message said:

> what? peter cole [censored] on something he doesn't know about?
> surely that would never happen!

Whatever.

Quoted message said:

Quoted message said:

You forget, it was the Boeing guy (and anyone else you care to
consult) who used the term.

er, you mean the guy using emotive language designed to stir up
controversy. "brittle" to most lay persons means that something
shatters like glass. this is /not/ the case with this material.

"Brittle" is a term commonly used to describe CF-epoxy composites by
experts in the field.

er, "brittle" is a term used by self-proclaimed "engineers" that don't
know what they're talking about but want to stir up fear by implying
cfrp shatters like glass.

Quoted message said:

Lack of "toughness" is another.

and that is [censored]. cfrp can be /extremely/ tough. see above for
misapplication of "fear".

Quoted message said:

Quoted message said:

Quoted message said:

>>> and apparently succeeding if the ridiculous bleating on r.b.t is a
>>> gauge.
>>
>> Nothing in common, actually. The Boeing engineer's primary charge
>> is that the testing protocols are insufficient for the new technology.
>
> the "new" 30 year old technology that's been used in mil aps that
> whole time. and it's especially ironic given that planes were made
> of wood, that natural composite.
> http://en.wikipedia.org/wiki/Hughes_H-4_Hercules
> http://www.warbirdalley.com/mossie.htm

> what? ignore facts? peter cole would never do that!

What "facts"? The problem is safety, specifically crashworthiness.

ah, the peter cole ethereal undefined [censored]. just like "impact".

so how much "crashworthiness" does a plane need peter? nose in at
700kts? would that be reasonable?

Boeing tested a fuselage section per existing FAA requirements and
claimed that those tests validated their computer models. The Boeing
employee claims that the tests, which were designed to certify metallic
fuselages, are not sufficient. I think he has a case.

based on what? emotive fear-mongering non-comprehension of the
materials? from the guy that thinks cfrp shatters like glass??? from
the guy that doesn't understand the distinction between elasticity and
plasticity??? yeah, that's a /real/ sound basis for judgment!

Quoted message said:

Quoted message said:

undefined emotive sensationalism is so much [censored]. especially from a
guy that calls himself an "engineer".

Quoted message said:

The Boeing engineer argues that the new material in a fuselage
application requires more testing to qualify it. His opinion is that
the design would fail such tests.

but boeing have tested to industry standards. what more do you want?
undefined "impact" testing?

The Boeing engineer said he wanted a fully loaded, full fuselage section
at 30 fps. He would also like to see fire resistance added to the test.

why does cfrp have to withstand /more/ than metal???

and the fire resistance is [censored] - the plane is /full/ of toxic
combustibles, not least of which is fuel. if you can't exit the plane
in 90 seconds, you're pork crackling. cfrp won't make any damned
difference to that.

Quoted message said:

Quoted message said:

Quoted message said:

>>> still, as part of the old saying goes, "you can fool some people
>>> all of the time", and thus it is proved.
>>
>> Nothing is "proved". You don't even have the facts straight.
>
> typical peter cole. cherry pick the points you want to argue and
> ignore the others that make them a crock.

You didn't (as usual) address the points I raised.

er, inability to read or understand basic science on your part is /not/
failure to address on mine.

Quoted message said:

Quoted message said:

Quoted message said:

I address every point you raise.

no you don't!!! what about the long and successful history of
composites in a/c over the decades. since the dawn of flight in fact.
you just routinely ignore anything inconvenient, then proceed as if
nothing is wrong.

Yeah, OK, wood was used first. I am aware of that, I've toured the
spruce goose, my dad was flown into London on a mosquito during the war.
I've worked on various boat hulls, wood plank, molded plywood, glassed
plywood, and plain glass. I'm very aware of the relative qualities.

The specific topic is crashworthiness of composite fuselages. This is a
new application.

it's not "new". and it's not inferior - your implication.

Quoted message said:

Quoted message said:

that's [censored].

Whatever.

Quoted message said:

Quoted message said:

You should return the courtesy -- but I suppose that's an oxymoron.

yeah, and the day you don't [censored] is the one i'm waiting for too.

Whatever.

Quoted message said:

Quoted message said:

> you're a bullshitter.
Whatever.

but you are.

Whatever.

get with the program. learn about this stuff /before/ you run about
like chicken little. buy a carbon fork [nashbar, $99, bike swap, much
less] and try to destroy it. go to an r/c model plane store and buy
some cfrp forms and mess about with them. break them. and please
please please /try/ to get the basic science right - you have no basis
for criticism if your fundamentals are wrong.

jim beam wrote:
<snip>

Quoted message said:

you have no basis
for criticism if your fundamentals are wrong.

make that "when", not "if".

An interesting paper on the challenges presented in designing a
crashworthy CF composite aircraft:

<http://nlr.nl/smartsite.dws?id=4366>

A couple of quotes:

"Traditionally, fuselages of fixed-wing transport aircraft
are made mostly of aluminium, a material with
considerable capacity for plastic deformation, hence,
an inherent capability to absorb energy in crash
situations. Since the last two decades, composite
materials are used more extensively to build aircraft
structures, although in civil transport aircraft, applications are
limited mainly to the empennage, the
outer wing and secondary structures. However,
application of composite materials to aircraft fuselages
becomes feasible rapidly, and the crashworthiness
aspect related to composite structures has become a
serious issue. The composites used for aerospace
structures are generally brittle materials with hardly
any capacity for plastic deformation, so
crashworthiness is no longer a materials aspect, but
requires a combined materials/structures/fabrication approach."

"Metals absorb energy by plastic deformation. For
metal structures, this applies to all failure modes:
tension, compression, bending, etc. Composites
absorb energy mainly by fiber breakage. It is important
to break a fiber many times over, rather than once
only. For composite structures, this seems possible only in a
compression mode without buckling, i.e., in a
stabilized configuration. Failure in tension or bending
usually doesn't lead to multiple fiber fractures.
Helicopter technology has indicated that carbon-fibers
are best for energy absorption, and aramid fibers are
best to provide stability and integrity of a crushing
structure. Solutions are therefore sought in mixed
laminates of both fiber types, either as a laminate with
different material plies or as hybrid fabrics."

It is also interesting to note in light of the Boeing flap, that the
drop test documented here produced results that didn't conform to the
model (for the overall structure), supporting the argument that full
scale drop tests may be the wisest way to go until the engineering is
better understood.

The important point contained in this document, from a bicycle component
point of view, is that CF composites are typically very bad at absorbing
energy, with the contrary sounding reality that CF composite structures
with very good energy absorbency can be designed. Unfortunately, bicycle
components are not made that way, and consequently retain the brittle
characteristics of the base material.

Energy absorbency in the form of gross crashes is probably not nearly as
important as cumulative low impact damage in bicycle components and the
ability to detect it, but it's still a consideration.

Peter Cole said:

An interesting paper on the challenges presented in designing a
crashworthy CF composite aircraft:

<http://nlr.nl/smartsite.dws?id=4366>

A couple of quotes:

"Traditionally, fuselages of fixed-wing transport aircraft
are made mostly of aluminium, a material with
considerable capacity for plastic deformation, hence,
an inherent capability to absorb energy in crash
situations. Since the last two decades, composite
materials are used more extensively to build aircraft
structures, although in civil transport aircraft, applications are
limited mainly to the empennage, the
outer wing and secondary structures. However,
application of composite materials to aircraft fuselages
becomes feasible rapidly, and the crashworthiness
aspect related to composite structures has become a
serious issue. The composites used for aerospace
structures are generally brittle materials with hardly
any capacity for plastic deformation, so
crashworthiness is no longer a materials aspect, but
requires a combined materials/structures/fabrication approach."

that's a fundamental misunderstanding. cfrp absorbs substantial energy
as it breaks - it's extremely tough, remember?

Quoted message said:

"Metals absorb energy by plastic deformation. For
metal structures, this applies to all failure modes:
tension, compression, bending, etc. Composites
absorb energy mainly by fiber breakage. It is important
to break a fiber many times over, rather than once
only. For composite structures, this seems possible only in a
compression mode without buckling, i.e., in a
stabilized configuration. Failure in tension or bending
usually doesn't lead to multiple fiber fractures.
Helicopter technology has indicated that carbon-fibers
are best for energy absorption, and aramid fibers are
best to provide stability and integrity of a crushing
structure. Solutions are therefore sought in mixed
laminates of both fiber types, either as a laminate with
different material plies or as hybrid fabrics."

and?

Quoted message said:

It is also interesting to note in light of the Boeing flap, that the
drop test documented here produced results that didn't conform to the
model (for the overall structure), supporting the argument that full
scale drop tests may be the wisest way to go until the engineering is
better understood.

The important point contained in this document, from a bicycle component
point of view, is that CF composites are typically very bad at absorbing
energy,

absolutely incorrect. they absorb substantial energy - they just do it
differently!

Quoted message said:

with the contrary sounding reality that CF composite structures
with very good energy absorbency can be designed.

how inconvenient to everything you've just said!

Quoted message said:

Unfortunately, bicycle
components are not made that way, and consequently retain the brittle
characteristics of the base material.

says who??? that's a massive presumption, and a completely wrong one if
the torn head tube example is anything to go by.

Quoted message said:

Energy absorbency in the form of gross crashes is probably not nearly as
important as cumulative low impact damage in bicycle components and the
ability to detect it, but it's still a consideration.

what is "impact"??? a 0.1ms^-1 collision with a dead chicken? or a
100ms^-1 collision with a tungsten spike of 60 degree cone tip angle,
0.001mm tip radius and connected to a 2,000kg pendulum? unless you
define "impact", it means _nothing_.

as for "probably" being damaged by "low impact", that's absolutely
contradicted by excellent fatigue characteristics. reaching to the
ethereal "unknown" scare factor is just chicken little trying to be
afraid and wanting to tell everybody else to be the same.

why don't you do the experiments i suggested?

jim beam said:

Peter Cole said:

An interesting paper on the challenges presented in designing a
crashworthy CF composite aircraft:

<http://nlr.nl/smartsite.dws?id=4366>

A couple of quotes:

"The composites used for aerospace
structures are generally brittle materials with hardly
any capacity for plastic deformation, so
crashworthiness is no longer a materials aspect, but
requires a combined materials/structures/fabrication approach."

that's a fundamental misunderstanding. cfrp absorbs substantial energy
as it breaks

You'll have to take that up with the scientists -- all of them.

Quoted message said:

- it's extremely tough, remember?

No, it isn't. That's the whole point.

Peter Cole said:

jim beam said:

Peter Cole said:

An interesting paper on the challenges presented in designing a
crashworthy CF composite aircraft:

<http://nlr.nl/smartsite.dws?id=4366>

A couple of quotes:

"The composites used for aerospace
structures are generally brittle materials with hardly
any capacity for plastic deformation, so
crashworthiness is no longer a materials aspect, but
requires a combined materials/structures/fabrication approach."

that's a fundamental misunderstanding. cfrp absorbs substantial
energy as it breaks

You'll have to take that up with the scientists -- all of them.

fortunately, we won't have to take it up with the "engineers" - they'll
all be doing their chicken little thing and bleating that cfrp shatters
like glass.

Quoted message said:

Quoted message said:

- it's extremely tough, remember?

No, it isn't. That's the whole point.

er, who was it admitting /what/ about the energy absorption of cfrp used
in f1 cars??? oh, it was /you/!!!

jim beam said:

Peter Cole said:

jim beam said:

Peter Cole wrote:
> An interesting paper on the challenges presented in designing a
> crashworthy CF composite aircraft:
>
> <http://nlr.nl/smartsite.dws?id=4366>
>
> A couple of quotes:
>
> "The composites used for aerospace
> structures are generally brittle materials with hardly
> any capacity for plastic deformation, so
> crashworthiness is no longer a materials aspect, but
> requires a combined materials/structures/fabrication approach."

that's a fundamental misunderstanding. cfrp absorbs substantial
energy as it breaks

You'll have to take that up with the scientists -- all of them.

fortunately, we won't have to take it up with the "engineers" - they'll
all be doing their chicken little thing and bleating that cfrp shatters
like glass.

Whatever.

Quoted message said:

Quoted message said:

Quoted message said:

- it's extremely tough, remember?

No, it isn't. That's the whole point.

er, who was it admitting /what/ about the energy absorption of cfrp used
in f1 cars??? oh, it was /you/!!!

As I've posted several times (with cites), it is possible to create
energy absorbent structures with composites, but that doesn't mean the
material is inherently energy absorbent, quite the contrary in the case
of CF.

Peter Cole said:

jim beam said:

Peter Cole said:

jim beam wrote:
> Peter Cole wrote:
>> An interesting paper on the challenges presented in designing a
>> crashworthy CF composite aircraft:
>>
>> <http://nlr.nl/smartsite.dws?id=4366>
>>
>> A couple of quotes:
>>
>> "The composites used for aerospace
>> structures are generally brittle materials with hardly
>> any capacity for plastic deformation, so
>> crashworthiness is no longer a materials aspect, but
>> requires a combined materials/structures/fabrication approach."
>
> that's a fundamental misunderstanding. cfrp absorbs substantial
> energy as it breaks

You'll have to take that up with the scientists -- all of them.

fortunately, we won't have to take it up with the "engineers" -
they'll all be doing their chicken little thing and bleating that cfrp
shatters like glass.

Whatever.

Quoted message said:

Quoted message said:

> - it's extremely tough, remember?

No, it isn't. That's the whole point.

er, who was it admitting /what/ about the energy absorption of cfrp
used in f1 cars??? oh, it was /you/!!!

As I've posted several times (with cites), it is possible to create
energy absorbent structures with composites, but that doesn't mean the
material is inherently energy absorbent, quite the contrary in the case
of CF.

typical peter cole b.s. you're just trying to twist facts to suit your
[incorrectly] entrenched position.

oh, and have you done those experiments i asked of you yet? what were
your results?