787 delamination
Engineering vs Manufacturing
If you read the detail on Flightblogger, it details how this is a manufacturing issue and not a design problem.
The industry has been headed toward a philosophy of separating design from manufacturing in order to more easily outsource the latter. And then to lay off the design staff once the drawings are out the door. That comes back to bite them in the
every time. But they keep doing it.
Join Date: Oct 2007
Location: Cumbria
Posts: 170
Likes: 0
Received 0 Likes
on
0 Posts
But it would appear that the cracks in the wingy-bits are caused by a manufacturing process error? and there are several hundred of the little feet so lose 1 presumably you don;t lose them all at the same time?
but the fuselage issue being structural and pressurised menas that if it goes the whole lot goes in one go?
I'm just baffled by the lack of interest in the fuselage issue compared to the wing feet issue.
but the fuselage issue being structural and pressurised menas that if it goes the whole lot goes in one go?
I'm just baffled by the lack of interest in the fuselage issue compared to the wing feet issue.
Join Date: Jan 2005
Location: France
Posts: 2,315
Likes: 0
Received 0 Likes
on
0 Posts
Plywood, in a way, is also a multi-layer carbon fibre composite, no?
Somehow, over the years, some design and material knowledge get lost.....
Just think of the DH Mosquito, or some of the late-WWII German aircraft, or maybe even the "Spruce Goose" ?
No, I'm not suggesting Boeing should have built the DreamyLiner from plywood.
But they could have learned from the experience from those days..... if it had been transmitted through the generations.....
CJ
Join Date: Dec 2007
Location: Cornwall-on-Hudson, New York
Posts: 875
Likes: 0
Received 0 Likes
on
0 Posts
It admittedly was some years ago, when Boeing first began using composite parts, but a Boeing engineer said to a friend of mine, "The more we learn about composites, the better aluminum looks."
Whether it's the Engineer or the person that pours the glue, there have been so many failures of composites in 'high end' racing yachts that are all due to being unable to properly inspect the finished product.
Pete Goss and 'Philips'. 600mm by several Metres of doubler on each hull - no bond.
Many carbon keels - not completely cured.
Can't remember which, but an Aus or Kiwi AC boat snapped in two.
De-lam from foam cores, so many.
None of which are the fault of the Carbon/Aramid fibre, but most certainly the fault of the manufacturing and inspection process. Which was designed by somebody.
R&D on those was very much limited by budget. Formula One is another big user, and we hear a lot less about their failures, perhaps because we expect the cars to break from time to time, and that a wheel falling off seems a lot less frightening than a keel. (To the spectator). Budget is less of a problem, but we just don't hear about the failures, of which there must be many.
Others please chip in - I don't go much further than the Beeb for F1, and am not aware of any pprune-type motor racing sites.
Carbon (or even Graphene) composites are quite obviously the future, but I'd really like to have more confidence than I do currently.
This a reply to a 787 thread, but, A380, alloy spar in the horizontal stab, with a Carbon skin? Alloy contracts with reducing temps, Carbon expands. Hmm.
Pete Goss and 'Philips'. 600mm by several Metres of doubler on each hull - no bond.
Many carbon keels - not completely cured.
Can't remember which, but an Aus or Kiwi AC boat snapped in two.
De-lam from foam cores, so many.
None of which are the fault of the Carbon/Aramid fibre, but most certainly the fault of the manufacturing and inspection process. Which was designed by somebody.
R&D on those was very much limited by budget. Formula One is another big user, and we hear a lot less about their failures, perhaps because we expect the cars to break from time to time, and that a wheel falling off seems a lot less frightening than a keel. (To the spectator). Budget is less of a problem, but we just don't hear about the failures, of which there must be many.
Others please chip in - I don't go much further than the Beeb for F1, and am not aware of any pprune-type motor racing sites.
Carbon (or even Graphene) composites are quite obviously the future, but I'd really like to have more confidence than I do currently.
This a reply to a 787 thread, but, A380, alloy spar in the horizontal stab, with a Carbon skin? Alloy contracts with reducing temps, Carbon expands. Hmm.
Last edited by boguing; 9th Feb 2012 at 20:21.
Join Date: Nov 2010
Location: The World
Posts: 69
Likes: 0
Received 0 Likes
on
0 Posts
[quote]boguing
Whether it's the Engineer or the person that pours the glue, there have been so many failures of composites in 'high end' racing yachts that are all due to being unable to properly inspect the finished product. [quote]
Having had some composite experience in motorsport ( not at current F1 level ) boguing raises many valid points. When one sees the protocols and clean room conditions that are used for manufacturing of motorsport components ( which do not have the life cycle expectations of a commercial aircraft, nor the dimensional mass of 787 components ) the probability of issues related to non-compliance of the manufacturing protocols, tooling and material problems, human error and unforseen problems are high in a 787 sized project. Added to this are commercial pressures to delivery schedules and the requirement to be profitable.
No doubt there are very high levels of automation in the 787 manufacturing process, but it's unlikely there are no areas that do not require manual processes to completition. Which raises the question of the experience/training levels of the production staff, again dictated by keeping manufacturing costs to a minimum.
Prototyping is one thing, productionizing is a serious challenge.
Whether it's the Engineer or the person that pours the glue, there have been so many failures of composites in 'high end' racing yachts that are all due to being unable to properly inspect the finished product. [quote]
Having had some composite experience in motorsport ( not at current F1 level ) boguing raises many valid points. When one sees the protocols and clean room conditions that are used for manufacturing of motorsport components ( which do not have the life cycle expectations of a commercial aircraft, nor the dimensional mass of 787 components ) the probability of issues related to non-compliance of the manufacturing protocols, tooling and material problems, human error and unforseen problems are high in a 787 sized project. Added to this are commercial pressures to delivery schedules and the requirement to be profitable.
No doubt there are very high levels of automation in the 787 manufacturing process, but it's unlikely there are no areas that do not require manual processes to completition. Which raises the question of the experience/training levels of the production staff, again dictated by keeping manufacturing costs to a minimum.
Prototyping is one thing, productionizing is a serious challenge.
Join Date: Mar 2001
Location: I wouldn't know.
Posts: 4,499
Likes: 0
Received 0 Likes
on
0 Posts
And on the other hand much more aviation like, there are thousands of glider planes manufactured out of different fibre materials including aramid, polyamid and of course carbon. Very very few manufacturing related incidents or accidents, most stuff that happens is good old human factors stuff. Newer SEP planes like the Diamond Air series, or before that Grob trainers and more recently Cessna 300/400 and of course the Cirrus family. All of them built out of composite materials.
Composite is nothing new, in fact airplanes have been build in composite structure since the 1950iies. However it seems hard to transport the lessons learned onto newer commercial projects, including the 787.
Composite is nothing new, in fact airplanes have been build in composite structure since the 1950iies. However it seems hard to transport the lessons learned onto newer commercial projects, including the 787.
Join Date: Sep 2010
Location: earth
Posts: 1,341
Likes: 0
Received 0 Likes
on
0 Posts
Denti
Tried and proven on light aircraft and certain structure on large aircraft, you can hardly relate this to a large fuscelage. You can make an RC aircraft out of foam and plastic, would it stand up full scale? I know, a bit draumatic but there is NO precedent for the 787 and using standard processes on what we know about this material may fail our expectations as we experience failures in design and manufacturing standards.
The in service test bed is a risky one.
The in service test bed is a risky one.
Denti, I accept that.
If my Pa's Pik 17/19? hadn't had carbon in it he would not have survived the accident that he had.
I will be trusting an Extra 300's Carbon spar soon.
Good products.
It's the flipside - when the bits start to get bigger and more 'engineered' than simple spars and skins.
The current Volvo Race management have an independent surveyor using ultrasound on all of the boats in Sanya (China) at the moment.
One of the boats suffered some hull delamination early in the first leg, several others have had rig failures, again. The headline sponsor is trying to minimise the risk.
The shock loads put into these boats is way in excess of what the worst pilot could do to his aircraft (short of what Pa did to his anyway..) but the fact that an intrinsically weakened structure (through either misunderstanding of the load at a point, or poor manufacture, again at a point) is brutally punished by the completely unforgiving good structure surrounding it.
Yacht design R&D is heavily restrained by budget, and they have made major errors in the past. Would an Aero Engineer ever suggest a welded keel structure? Simon LeBon's boat Drum was the first casualty. There have been tens more of those, some fatal.
My main point is that Carbon is a fab material. Not necessarily the way it's stuck together though. It's the fact that it is so hard to inspect that gives me:-
Huge concern on a boat.
Not much concern on smaller structures - where the person with the glue/heat/vacuum knows what they are doing in a highly regulated industry.
It's the big composite stuff that I just don't know how to react to - in the same way that I believe fervently in nuclear power. But just how much do we really need to spend on testing?
If my Pa's Pik 17/19? hadn't had carbon in it he would not have survived the accident that he had.
I will be trusting an Extra 300's Carbon spar soon.
Good products.
It's the flipside - when the bits start to get bigger and more 'engineered' than simple spars and skins.
The current Volvo Race management have an independent surveyor using ultrasound on all of the boats in Sanya (China) at the moment.
One of the boats suffered some hull delamination early in the first leg, several others have had rig failures, again. The headline sponsor is trying to minimise the risk.
The shock loads put into these boats is way in excess of what the worst pilot could do to his aircraft (short of what Pa did to his anyway..) but the fact that an intrinsically weakened structure (through either misunderstanding of the load at a point, or poor manufacture, again at a point) is brutally punished by the completely unforgiving good structure surrounding it.
Yacht design R&D is heavily restrained by budget, and they have made major errors in the past. Would an Aero Engineer ever suggest a welded keel structure? Simon LeBon's boat Drum was the first casualty. There have been tens more of those, some fatal.
My main point is that Carbon is a fab material. Not necessarily the way it's stuck together though. It's the fact that it is so hard to inspect that gives me:-
Huge concern on a boat.
Not much concern on smaller structures - where the person with the glue/heat/vacuum knows what they are doing in a highly regulated industry.
It's the big composite stuff that I just don't know how to react to - in the same way that I believe fervently in nuclear power. But just how much do we really need to spend on testing?
Last edited by boguing; 10th Feb 2012 at 18:05.
It's the big composite stuff that I just don't know how to react to
is it volumetric, density per volumn or;
area (the size of a mack truck) or;
weight (something that can't be flown into the air on just one engine)
Damn, picked up on a conveniently loose adjective.
By a trusted ppruner too.
I suppose 'big' as in:-
How much of this cylindrical fuselage can we do in one go?
Since you have the mould (mold) for rib 3 set up, can you knock out 50 by lunchtime?
Or, more technical.
The post cure shape is getting close to limits one way. The bit that it fits with is approaching limits 'tother way. Do we redesign both moulds or just glue them up anyway?
Industrial big.
By a trusted ppruner too.
I suppose 'big' as in:-
How much of this cylindrical fuselage can we do in one go?
Since you have the mould (mold) for rib 3 set up, can you knock out 50 by lunchtime?
Or, more technical.
The post cure shape is getting close to limits one way. The bit that it fits with is approaching limits 'tother way. Do we redesign both moulds or just glue them up anyway?
Industrial big.
Join Date: Nov 2010
Location: The World
Posts: 69
Likes: 0
Received 0 Likes
on
0 Posts
Big ; Some random thoughts . With prepregs, temperature and humidity are critical during the fabrication stage also. The larger the building, the harder it is to maintain control. Some materials are working time critical, if has been kept in cool storage, does it need x time in ambient temp before usage? Then there is the curing process(es).
Is the delamination area single skin, honeycomb or a secondary bond area ; we don't know ( yet ) whether manufacture or design is the cause, but size can present
challenges on large composite component. Protocols should be adhered to but commercial considerations would add pressure to continue in the event of an
" oops ". The $$$ involved are frightening..................
[quote] boguing
Not much concern on smaller structures - where the person with the glue/heat/vacuum knows what they are doing in a highly regulated industry.
[quote]
Very good summation.
Is the delamination area single skin, honeycomb or a secondary bond area ; we don't know ( yet ) whether manufacture or design is the cause, but size can present
challenges on large composite component. Protocols should be adhered to but commercial considerations would add pressure to continue in the event of an
" oops ". The $$$ involved are frightening..................
[quote] boguing
Not much concern on smaller structures - where the person with the glue/heat/vacuum knows what they are doing in a highly regulated industry.
[quote]
Very good summation.
Join Date: Jan 2005
Location: France
Posts: 2,315
Likes: 0
Received 0 Likes
on
0 Posts
I'm following this with interest.
I can write 'aeronautical engineer' behind my name, so I've got some knowledge about structural engineering, even if I sailed off into the flight control world.
As I mentioned earlier..... laminated structures date back to WWII (and before).... the stuff was called plywood. Just remember the Mosquito.
And glue in aviation goes back quite some time too.... may I remind you of Redux, and the Fokker F-27 ?
(And no, the F-27 isn't all glued.... I still remember being taught riveting on F-27 wing panels.)
My point being.... design engineering is one thing, production engineering is another.... and indeed, if the two are not talking to each other enough.... things come apart.
CJ
I can write 'aeronautical engineer' behind my name, so I've got some knowledge about structural engineering, even if I sailed off into the flight control world.
As I mentioned earlier..... laminated structures date back to WWII (and before).... the stuff was called plywood. Just remember the Mosquito.
And glue in aviation goes back quite some time too.... may I remind you of Redux, and the Fokker F-27 ?
(And no, the F-27 isn't all glued.... I still remember being taught riveting on F-27 wing panels.)
My point being.... design engineering is one thing, production engineering is another.... and indeed, if the two are not talking to each other enough.... things come apart.
CJ
boguing
Well your latest post certainly nailed it and have now provided some damn good explanations on this techical forum 
Damn, picked up on a conveniently loose adjective.
Join Date: Nov 2010
Location: The World
Posts: 69
Likes: 0
Received 0 Likes
on
0 Posts
These may be interesting ;
Boeing 787 Dreamliner - Wikipedia, the free encyclopedia
File:787fuselage.jpg - Wikipedia, the free encyclopedia
Boeing 787 Update : Composites World
Boeing 787 Dreamliner - Wikipedia, the free encyclopedia
File:787fuselage.jpg - Wikipedia, the free encyclopedia
Boeing 787 Update : Composites World
Last edited by TZ350; 10th Feb 2012 at 22:53.
Join Date: Feb 2009
Location: Jungles of SW London
Age: 77
Posts: 354
Likes: 0
Received 0 Likes
on
0 Posts
Boquing
ChristiaanJ
A good few years ago now, we had a CT Scanner in the research labs of an oil exploration company. They never used it for people, it was for scanning rock samples. It was actually fascinating stuff for my peers and myself looking after it.
The rock was often repressurised to that which it had been under when drilled from the bottom of a well and, in order to do that, it was encased in a variety of (usually) aluminium or even steel pressure vessels. I remember the really scary one was the size of a dustbin, pressurised to 800psi (I'm sorry, I'm a Chain/Hundredwieght/Fortnight man
) with GAS 
and 'flooded' with live crude oil at about 150C!!
At one time they ran an experiment that used fibre tubes - probably early carbon fibre, this was late eighties - to repressurise 5 inch core samples. These vessels were a (carbon) fibre tube about two feet long with truly massive stainless steel flanges on each end and in use were pressurised to 22 or 23 thousand psi, some even more than that.
The thing being, it wasn't until they got these things - live - onto the CT scanner and scanned down the length of the tube, that they saw for the first time there were huge voids, about a layer thick, sometimes over a third of the circumference and a big chunk of the length!
They had been manufactured to the highest standards - believe me, this company were class in that respect - and designed for astronomic pressures, but they didn't know there was anything wrong until a new technique (CT imaging) was used for some other purpose.
Just my few penn'orth.
Roger.
None of which are the fault of the Carbon/Aramid fibre, but most certainly the fault of the manufacturing and inspection process. Which was designed by somebody.
My main point is that Carbon is a fab material. Not necessarily the way it's stuck together though. It's the fact that it is so hard to inspect that gives me:-
Huge concern on a boat.
Huge concern on a boat.
My point being.... design engineering is one thing, production engineering is another.... and indeed, if the two are not talking to each other enough.... things come apart.
The rock was often repressurised to that which it had been under when drilled from the bottom of a well and, in order to do that, it was encased in a variety of (usually) aluminium or even steel pressure vessels. I remember the really scary one was the size of a dustbin, pressurised to 800psi (I'm sorry, I'm a Chain/Hundredwieght/Fortnight man
) with GAS and 'flooded' with live crude oil at about 150C!!At one time they ran an experiment that used fibre tubes - probably early carbon fibre, this was late eighties - to repressurise 5 inch core samples. These vessels were a (carbon) fibre tube about two feet long with truly massive stainless steel flanges on each end and in use were pressurised to 22 or 23 thousand psi, some even more than that.
The thing being, it wasn't until they got these things - live - onto the CT scanner and scanned down the length of the tube, that they saw for the first time there were huge voids, about a layer thick, sometimes over a third of the circumference and a big chunk of the length!
They had been manufactured to the highest standards - believe me, this company were class in that respect - and designed for astronomic pressures, but they didn't know there was anything wrong until a new technique (CT imaging) was used for some other purpose.
Just my few penn'orth.
Roger.
But it would appear that the cracks in the wingy-bits are caused by a manufacturing process error? and there are several hundred of the little feet so lose 1 presumably you don;t lose them all at the same time?
but the fuselage issue being structural and pressurised menas that if it goes the whole lot goes in one go?
I'm just baffled by the lack of interest in the fuselage issue compared to the wing feet issue.
but the fuselage issue being structural and pressurised menas that if it goes the whole lot goes in one go?
I'm just baffled by the lack of interest in the fuselage issue compared to the wing feet issue.
Join Date: Oct 2007
Location: Cumbria
Posts: 170
Likes: 0
Received 0 Likes
on
0 Posts
Ah well, so that's alright then?
But presumeably is subject to a whole bunch of stresses in a whole bunch of different directions, and if it were to delaminate in flight?
And if it delaminates somewhere unpressurised does this mean that it could do the same somewhere pressurised?
But presumeably is subject to a whole bunch of stresses in a whole bunch of different directions, and if it were to delaminate in flight?
And if it delaminates somewhere unpressurised does this mean that it could do the same somewhere pressurised?
Join Date: Dec 2001
Location: what U.S. calls Žold EuropeŽ
Posts: 941
Likes: 0
Received 0 Likes
on
0 Posts
but the fuselage issue being structural and pressurised menas that if it goes the whole lot goes in one go?
...
And if it delaminates somewhere unpressurised does this mean that it could do the same somewhere pressurised?
...
And if it delaminates somewhere unpressurised does this mean that it could do the same somewhere pressurised?
As a pressurized fuselage creates tension in the skin, delamination in the pressurized area is not critical. You will probably first have a problem to maintain the fuselage pressurized due to the air leak before you reach any critical strength condition. I would be more worried about delaminations in the upper wing skin where it under extreme compression. And so did Boeing when they found issues there.