Sponsor Message:
Civil Aviation Forum
My Starred Topics | Profile | New Topic | Forum Index | Help | Search 
Boeing Completes Destructive Testing On 787  
User currently offlinePhilSquares From , joined Dec 1969, posts, RR:
Posted (5 years 9 months 1 week 1 day 22 hours ago) and read 14911 times:

FYI

http://biz.yahoo.com/prnews/081115/clsa901.html?.v=11

36 replies: All unread, showing first 25:
 
User currently offlineStitch From United States of America, joined Jul 2005, 30865 posts, RR: 86
Reply 1, posted (5 years 9 months 1 week 1 day 22 hours ago) and read 14905 times:
Support Airliners.net - become a First Class Member!

So I take it this was the "150%" test of the wings themselves? Or is that test still to come? The article text implies the former.

User currently offlineJAAlbert From United States of America, joined Jan 2006, 1573 posts, RR: 1
Reply 2, posted (5 years 9 months 1 week 1 day 22 hours ago) and read 14849 times:

Although the article mentions the 150% minimum for wings, the article is specifically discussing in detail the wing box, not the wings. Wing testing always seems a big event, so I think Boeing would have announced wing destructive testing had it occurred.

How exactly does one perform destructive testing on a wing box?


User currently offlineKaneporta1 From Greece, joined May 2005, 739 posts, RR: 12
Reply 3, posted (5 years 9 months 1 week 1 day 22 hours ago) and read 14808 times:

The article is not very informative but I think what was tested was not the wing but one of the structural demontrator boxes. It is mentioned in the article that it was half the span of the wing and I'm not sure if this is enough to satisfy the certification authorities. On the other hand, it would be more than enough to give Boeing and indication on the behaviour of a composite "box" structure under ultimate load conditions and allow them to make modifications (if needed) to the wing design, before it's tested for certification.


I'd rather die peacefully in my sleep, like my grandfather, not terrified and screaming, like his passengers
User currently offlineOldAeroGuy From United States of America, joined Dec 2004, 3499 posts, RR: 66
Reply 4, posted (5 years 9 months 1 week 1 day 21 hours ago) and read 14737 times:



Quoting JAAlbert (Reply 2):
the article is specifically discussing in detail the wing box,

This is the piece of structure that in earlier releases had been described as having a known under strength problem. Giving it a clean bill of health is the most significant thing about this announcement.

It appears that the full wing loading test is still to come.



Airplane design is easy, the difficulty is getting them to fly - Barnes Wallis
User currently offlinePhilSquares From , joined Dec 1969, posts, RR:
Reply 5, posted (5 years 9 months 1 week 1 day 21 hours ago) and read 14654 times:

Just a further update:



http://www.flightglobal.com/articles...-destructive-test-on-787-wing.html


User currently offlineAlessandro From , joined Dec 1969, posts, RR:
Reply 6, posted (5 years 9 months 1 week 1 day 18 hours ago) and read 14197 times:

Finally some good news, hope the wings will be as good as the wingbox.

User currently offlineTdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 7, posted (5 years 9 months 1 week 1 day 16 hours ago) and read 13717 times:



Quoting Stitch (Reply 1):
So I take it this was the "150%" test of the wings themselves? Or is that test still to come?

Still to come. That's the last test you can do, since it can destroy the static test frame.

Tom.


User currently onlineRuscoe From Australia, joined Aug 1999, 1557 posts, RR: 2
Reply 8, posted (5 years 9 months 1 week 1 day 15 hours ago) and read 12836 times:

Did I miss something?

It does not say anywhere I read, that the structure met it's design loads.

The fact that the article does not, leads me to believe that it may not have, or alternatively they have lost the plot on Press releases.

Ruscoe


User currently offlinePhilSquares From , joined Dec 1969, posts, RR:
Reply 9, posted (5 years 9 months 1 week 1 day 15 hours ago) and read 12606 times:



Quoting Ruscoe (Reply 8):
Did I miss something?

It does not say anywhere I read, that the structure met it's design loads.

Yes you did miss "something"!

"Successful completion of the wing box destruction test marks a major step forward in highlighting the innovation on the 787," said Mark Jenks, vice president of 787 Development.


User currently offlineAirNZ From , joined Dec 1969, posts, RR:
Reply 10, posted (5 years 9 months 1 week 1 day 15 hours ago) and read 12485 times:



Quoting PhilSquares (Reply 9):
Yes you did miss "something"!

Perhaps, but I can also see where Ruscoe is coming from. Your highlighted text is a clear implication yes......but while a test can be successfully completed, such in itself does not mean whatever was being tested passed. I'm not necessarily questioning it, but just pointing that the Boeing press release is most certainly not definitive in what exactly it is meaning.


User currently offlineStitch From United States of America, joined Jul 2005, 30865 posts, RR: 86
Reply 11, posted (5 years 9 months 1 week 1 day 14 hours ago) and read 12265 times:
Support Airliners.net - become a First Class Member!

If it had failed, we can safely assume that it would have been front page news since the media loves misery and Boeing has certainly been wallowing in it's share, as of late.

User currently offlineCARST From Germany, joined Jul 2006, 816 posts, RR: 1
Reply 12, posted (5 years 9 months 1 week 1 day 14 hours ago) and read 12139 times:



Quote:
Boeing has given little additional information, but a spokeswoman for the company says that the structure passed the test.

Read the whole article...


User currently offlinePlaneInsomniac From Canada, joined Nov 2007, 678 posts, RR: 0
Reply 13, posted (5 years 9 months 1 week 1 day 14 hours ago) and read 11961 times:

Hm, sounds more like a sort of full-scale mock-up test on the wing box to me.

From http://biz.yahoo.com/prnews/081115/clsa901.html?.v=11
"Boeing [...] completed destructive testing today on a full-scale composite wing box of the 787 Dreamliner"

From http://www.flightglobal.com/articles...destructive-test-on-787-wing.html:
"In addition to determining the strength of the structure, the test helps us verify the analytical methods we have used to calculate the loads the structure will have to carry."

Not to be too negative, but they are still validating their analytical methods?



Am I cured? Slept 5 hours on last long-haul flight...
User currently offlineStitch From United States of America, joined Jul 2005, 30865 posts, RR: 86
Reply 14, posted (5 years 9 months 1 week 1 day 13 hours ago) and read 11543 times:
Support Airliners.net - become a First Class Member!



Quoting PlaneInsomniac (Reply 14):
Not to be too negative, but they are still validating their analytical methods?

What is so surprising about this? This is the first time they have tested an entire wingbox structure so it builds on the data they have learned from the smaller structural tests they have already completed and makes those methods that much more accurate thanks to new information.


User currently offlineTdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 15, posted (5 years 9 months 1 week 1 day 13 hours ago) and read 11368 times:



Quoting PlaneInsomniac (Reply 14):
Not to be too negative, but they are still validating their analytical methods?

Of course. They'll still be validating analytical methods well after the plane enters service.

Tom.


User currently offlineOsiris30 From Barbados, joined Sep 2006, 3192 posts, RR: 25
Reply 16, posted (5 years 9 months 1 week 1 day 12 hours ago) and read 11041 times:



Quoting PlaneInsomniac (Reply 14):
Not to be too negative, but they are still validating their analytical methods?

Yes, just as Airbus was when they broke their wing at what was it, 147%. It's part of FEM. You're always cross-checking the computed result against reality. FEM is never completely right, it's just varying degrees of wrong that you hope are within design tolerances.

Quoting Ruscoe (Reply 15):
Thankyou., but you know, that could mean anything, in the world of PR.

Oh for the love of god. Boeing is going to post the video and more information on the 18th (as per the article). If they give it all to the press it won't be such a big deal on their site. Once you're on Boeing's site they can plug their product more than they will ever get in a media clipping.

Quoting PlaneInsomniac (Reply 17):
The implication that any sort of testing on the 787 has been completed is just plain wrong.

Speaking of vague, poorly worded statements  Wink SOME destructive testing has been carried out on components of the 787, the 787 being the sum of its components, therefore SOME of the destructive testing has been done. *Your* statement is just plain wrong, the thread statement is at least partially correct.

Quoting PlaneInsomniac (Reply 17):
After having read the linked articles, my impression is more that of a rather hypothetical laboratory test on a single piece of the plane

The *only* way to test *just that* component of the 787 is to test it in isolation. Furthermore, they likely went the extra mile with the wingbox since they had issues with them previously. Finally, the wingbox is one of the most 'loaded' parts of an aircraft's structure IIRC.



I don't care what you think of my opinion. It's my opinion, so have a nice day :)
User currently offlineAmicus From United States of America, joined Mar 2007, 43 posts, RR: 0
Reply 17, posted (5 years 9 months 1 week 1 day 10 hours ago) and read 10017 times:

Clearly, at least in my opinion, the wing box test under discussion is an interim step only. Also note that release from Boeing PR states that the wing ribs are monolithic aluminum whilst the remainder of the structure is CF/epoxy. This is clearly a design error due to the CTE (coefficient of thermal expansion) stresses induced between the CF and aluminum. I would predict that a design change is required to better match CTE's if Boeing isn't already planning for a change on production aircraft. Given the differential CTE stresses involved, the aluminum will be subjected to high rate fully reversed fatigue loadings in addition to any flight loads. I hope Boeing and Mitsubishi have already planned a change or I predict in-service issues arising due to thermal expansion mismatch. I would also suspect that another test of the redesigned wing box will be required.

User currently offlineCaryjack From United States of America, joined May 2007, 321 posts, RR: 0
Reply 18, posted (5 years 9 months 1 week 1 day 10 hours ago) and read 9923 times:

Given the following: "Boeing has completed destructive testing on the 787's all-composite wing box, a process which is part of the aircraft's certification program."

This quote implies that Boeing was required to test the wing box to destruction. Boeing did test it to 150% then destroyed it. I understand that composite pieces of all sorts have been destroyed in this very long process but are certain parts of the airframe required to be destroyed or was this an effort to prove Boeing's computer predictions on a very large and complex assembly? In other words, if Boeing can predict the failure mode on the wing box, they can predict it anywhere.

I understand that if a composite wing were tested to destruction that it would disintegrate into a cloud of carbon shards and dust, but a quick look at the photo provided by the OP indicates none of that. Is the wing box such a different type of design that it won't fail like a wing or have I misunderstood the cloud theory?

Quoting Osiris30 (Reply 20):
the thread statement is at least partially correct.

If Boeing was required to test the wing box to destruction, what other parts must be destroyed? Not the wings. If there are no more parts that are required to be tested to destruction then the thread statement is completely correct.
Thanks,
Cary


User currently onlineRuscoe From Australia, joined Aug 1999, 1557 posts, RR: 2
Reply 19, posted (5 years 9 months 1 week 1 day 10 hours ago) and read 9757 times:



Quoting Amicus (Reply 21):
This is clearly a design error due to the CTE (coefficient of thermal expansion) stresses induced between the CF and aluminum.

However I believe that some of the wing ribs in the 380 are CRP with Aluminium bonded between, or perhaps the other way around, so I suspect it is doable.

Ruscoe


User currently offlineTdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 20, posted (5 years 9 months 1 week 1 day 10 hours ago) and read 9638 times:



Quoting Amicus (Reply 21):
Also note that release from Boeing PR states that the wing ribs are monolithic aluminum whilst the remainder of the structure is CF/epoxy. This is clearly a design error due to the CTE (coefficient of thermal expansion) stresses induced between the CF and aluminum.

Not an error. That's been a public part of the 787 design for quite some time. CFRP spars and skins, metal ribs.

Quoting Amicus (Reply 21):
Clearly, at least in my opinion, the wing box test under discussion is an interim step only.

Of course...they've still go the ultimate strength tests on the full static test frame.

Quoting Amicus (Reply 21):
Given the differential CTE stresses involved, the aluminum will be subjected to high rate fully reversed fatigue loadings in addition to any flight loads.

True, but that's not necessarily a design problem. I'd be surprised if the ribs are fatigue critical.

Tom.


User currently offlineAmicus From United States of America, joined Mar 2007, 43 posts, RR: 0
Reply 21, posted (5 years 9 months 1 week 1 day 9 hours ago) and read 9514 times:

Tom,
Sorry, but you are wrong and clearly if you chew up around 65% of fatigue allowable caused by CTE stresses without any allowance whatsoever for any in-flight loads, you are going to have fatigue problems in-service. And if your position is that the ribs are not fatigue critical, then that makes no sense either. Most of the time you are accurate, but this time not. Again, this is a Boeing design error and needs to be fixed for production aircraft.


User currently offlineTdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 22, posted (5 years 9 months 1 week 1 day 6 hours ago) and read 8266 times:



Quoting Amicus (Reply 26):
Sorry, but you are wrong

It's happened before, and will again, but which part do you specifically mean I'm wrong about? Or do you mean all of it?

Quoting Amicus (Reply 26):
clearly if you chew up around 65% of fatigue allowable caused by CTE stresses without any allowance whatsoever for any in-flight loads, you are going to have fatigue problems in-service.

That's not clear at all. If your fatigue life is, say, 1 million cycles (not at all unusual for a part that's not fatigue critical) then you can burn a lot more than 65% and still have no fatigue issues.

Quoting Amicus (Reply 26):
And if your position is that the ribs are not fatigue critical, then that makes no sense either.

Why not? I very strongly suspect that the critical load case for a rib is ultimate wing load. If that's the case, the fatigue load is going to be a lot smaller than the ultimate load and, since fatigue life is an extremely non-linear function of stress, low fatigue stresses will drive the fatigue life *way* out, potentially orders of magnitude beyond the airplane's service life.

In addition, there's the fact that the CFRP components (spars and skins) are effectively orthogonal to the ribs...the ribs aren't exposed to anything but a tiny fraction of the thermal expansion of the skins and spars.

Quoting Amicus (Reply 26):
Again, this is a Boeing design error and needs to be fixed for production aircraft.

Out of curiosity, how could such a design error occur? Boeing has certainly not performed 100% on the 787 program, but they know a whole lot about composite manufacturing and have been doing it for a long time...I don't see how something as elementary as material compatibility would slip through so obviously.

If thermal mistmatch between aluminum and CFRP was as big a deal as you're suggesting, 777 floor should be failing all over the place (CFRP beams with aluminum seat tracks).

Tom.


User currently offlinePhilSquares From , joined Dec 1969, posts, RR:
Reply 23, posted (5 years 9 months 1 week 22 hours ago) and read 5722 times:



Quoting PlaneInsomniac (Reply 17):
Discussions about whether the test has succeeded or not aside, the quality of this thread could be improved a lot by including the words "wing box" in the thread title. The implication that any sort of testing on the 787 has been completed is just plain wrong.

Thanks for the suggestion. However, there are only so many characters that will fit into the title thread. I ASSUMED people would be able to figure out things when they read the two press releases. I guess I was wrong.

Further update at http://www.flightglobal.com/articles...-destructive-test-on-787-wing.html

And just to quote "Boeing has given little additional information, but a spokeswoman for the company says that the structure passed the test" So we can lay to rest any further conspiracy theories!


User currently offlineAmicus From United States of America, joined Mar 2007, 43 posts, RR: 0
Reply 24, posted (5 years 9 months 1 week 15 hours ago) and read 5228 times:

This is my last post re this matter, Tom. Please go and do the math instead of guessing and arguing without facts. To help you, the CTE of 2024-T6 aluminum is 13.7 / 10 x 6 in/in/degree F and CF is around zero CTE. If you assemble the wing box at 85 degrees and then you fly it or have a cold soak day, say typically -50 degrees F, then CTE delta length change for 17 foot long aluminum ribs is :
17x12 x (85+50) x 13.7/1 million = 0.377 inches change in length and CF doesn't move much if at all. Hence what are you going to do about nearly 0.4 inches change in length which strains the aluminum in tension and compresses the CF. On hot day soak that reverses and aluminum is put into compression.
This is a repetative fatigue loading independent and totally additional to any flight loads. Guessing at fatigue cycles doesn't hack it with me and nor do some other wishful statements such as "The ribs aren't critical in fatigue' or "Boeing would not make a mistake like that" without offering any supporting evidence. In summary, you have a CTE delta of 0.4 inches to account for and that stresses both the aluminum and CF, but aluminum is more critical in fatigue and is put into tension at both flight and low temperatures. And this is why in most other metallic areas Boeing uses titanium which has a far lower CTE differential. It is always bad design practice to mix CF and Aluminum over long lengths, period due to large CTE strains involved.
Again, run the numbers and please don't just guess at fatigue cycles et al. I worked on a C-130 NASA program which had similar problems and it failed re CTE issues too. Please don't guess, Tom, just run the numbers. I'm finished with this matter.


25 Trystero : I bellieve the video will be avaiable soon. I've seen a couple of wing destruction tests, and it hurts. It's necessary, I know, but it hurts...
26 Stitch : I admit that I find it odd that people continue to believe Boeing and Airbus, with decades of experience and tens of thousands of engineers, are total
27 Tdscanuck : I'm not the one that claimed that there must be a typo in the press release when, in fact, it was completely accurate. For starters, your ignoring th
28 Post contains links Dynamicsguy : The video's up now: http://787milestones.tpninteractive.com/ Amicus, Do you really think Boeing engineers don't account for thermal loads in their an
29 Ecb747 : Great to see some video from the test. However, I liked the video from the 777 wing test better, where you get to see the numbers as they count upward
30 Dynamicsguy : I noticed that they were pretty coy about how much it beat 150% by. And more so than when they talked about how much they beat it by for the barrel t
31 Nomadd22 : Was this test similar to the one where they decided to beef up the spars a little, or would that one have been much more limited in scope? You might t
32 AirTran717 : Boys, boys, BOYS! Please do get your testosterone levels under control and stop arguing. Boeing has been building planes for a long time.... 100 years
33 Nomadd22 : We are. A big one. I gather that the fatique frame will be tortured for years to pile up more cycles than any flying plane ever will, and make sure n
34 Pygmalion : Or the 777 stabilizer which is CFRP and Al ribs... its clear there is a design error there too...
35 United787 : Me too. I guess the 777 wingbreak test set the bar too high so they afraid that anything lower will look inferior...even though it is only required t
36 Tdscanuck : Or the A350! That just occured to me yesterday, but that's CFRP skins over Al/Ti frames. Tom.
Top Of Page
Forum Index

This topic is archived and can not be replied to any more.

Printer friendly format

Similar topics:More similar topics...
Boeing Close To Breakeven On 787 posted Sun May 21 2006 13:29:02 by Lumberton
Boeing Use Of Rfid On 787 Program posted Fri Nov 4 2005 20:25:21 by MrComet
Boeing Insider: F/As On 787/777 Question posted Sun Oct 19 2008 02:30:46 by Speedmarque
787 Horizontal Stab Complete Destructive Testing posted Tue Jul 1 2008 12:19:50 by NYC777
Boeing Provide Update On 787 Program: April 9th posted Mon Apr 7 2008 12:33:52 by Ahtohob346
Leeham: Airbus Sides With Boeing On 787 posted Thu Sep 20 2007 20:27:40 by Ikramerica
Boeing Faces Hurdles, Opportunities On The 787 posted Tue Aug 21 2007 21:57:07 by NYC777
DL/AA In Preliminary Talks With Boeing On 787 posted Sun Jun 17 2007 18:58:37 by Ual747-600
Boeing: No Delays On 787 posted Wed May 16 2007 07:07:44 by Clickhappy
Why Is Boeing Confident On 787 posted Thu Nov 23 2006 20:22:08 by SJCRRPAX