HOME  |  NEWS  |  BLOGS  |  MESSAGES  |  FEATURES  |  VIDEOS  |  WEBINARS  |  INDUSTRIES  |  FOCUS ON FUNDAMENTALS
  |  REGISTER  |  LOGIN  |  HELP
Comments
View Comments: Newest First|Oldest First|Threaded View
Page 1/2  >  >>
Cabe Atwell
User Rank
Blogger
Re: Composite Aircraft Repair Advances
Cabe Atwell   5/28/2014 2:34:51 AM
NO RATINGS
How are the composite materials when it comes to stress fracturing? Believe it or not, with aluminum, airline companies bolt a patch over the cracks until it can be sufficiently repaired, which may take months and in some cases years.

Ann R. Thryft
User Rank
Blogger
Re: Composite Aircraft Repair Advances
Ann R. Thryft   12/13/2011 1:28:04 PM
NO RATINGS

TJ, your points are well taken. The biggest problem of all in composite repair, though, compared to metal repair, is the lack of knowledge to identify damage in the first place, since it's much more difficult to detect. The next biggest problem is figuring out how to repair so many different materials with so many different uses and so many different possible procedures. And, by extension, lack of knowledge there, as well.


TJ McDermott
User Rank
Blogger
Re: Composite Aircraft Repair Advances
TJ McDermott   12/7/2011 9:29:40 PM
NO RATINGS
While repairs require more effort, composites would seem to be more damage resistant than an aluminum structure.

I looked for a video I'd seen several years ago: Boeing demonstrating a large skin section held vertically, and airline executives offered the chance to whack it with a sledge hammer.

I cannot find that video so this one will have to do:

http://www.youtube.com/watch?v=7dtk818WSiU&list=PLE618FBD35463D3BA&index=2&feature=plpp_video

Bombardier may go for traditional repair techniques on the areas in danger of ground support damage, but if composites shrug off the damage that would ding aluminum, then composites would seem to be the better bet.

 

 

Charles Murray
User Rank
Blogger
Re: Beyond material strength
Charles Murray   12/7/2011 3:32:15 PM
NO RATINGS
Follow-up from last night's comment: After I mentioned the American Airlines flight that crashed in 1979 after a design flaw left it vulnerable to maintenance damage, I tried to remember where I had once read about that accident. Here's the answer: Our distinguished columnist, Henry Petroski, wrote about it in his book, "To Engineer Is Human."

Ann R. Thryft
User Rank
Blogger
Re: Composite Aircraft Repair Advances
Ann R. Thryft   12/7/2011 12:54:27 PM
NO RATINGS

Thanks, Alex. The news just keeps coming out on this subject. Regarding standards, that's a really good question. One of the key critiques in the GAO report was the point that you can't base repair standards and best practices for composites on the same ones that were created for metal. There are too many differences across the board, and making the same assumptions or using the same templates would be ineffective and dangerous. That may be another reason why we're not hearing much yet about the details of repair whens and hows. I suspect it's a WIP.


Dave Palmer
User Rank
Platinum
Re: Beyond material strength
Dave Palmer   12/7/2011 10:23:19 AM
NO RATINGS
@Charles: You're absolutely right; materials selection involves many considerations besides the material's response to stress and strain -- which can be complicated enough, since the material may respond very differently at different temperatures and strain rates, and its properties may be different in different directions.  But how a given material will perform in your application also depends on its location in the galvanic series, among other things. Cost and manufacturability are always major concerns, too. Then there are externalities such as recyclability and end-of-life issues, sustainability and lifecycle emissions, etc.  And -- although I may be somewhat biased in this regard! -- this is why having a good materials engineer is a necessity.

Charles Murray
User Rank
Blogger
Beyond material strength
Charles Murray   12/6/2011 10:12:44 PM
NO RATINGS
This is a classic example of the need to beware that what looks good on paper may not always be so. As design engineers, we are often trained to consider matters of stress and strain -- bending, shear, torsional capacity, etc. But here we have a situation where the composite is apparently appropriate in matters of material strength, but not in matters of maintenance. Obviously, maintenance is a huge consideration for aircraft. In 1979, an American Airlines flight leaving Chicago O'Hare crashed, killing 271 people, after a design flaw left the engine pylon vulnerable to maintenance damage.

Alexander Wolfe
User Rank
Blogger
Re: Composite Aircraft Repair Advances
Alexander Wolfe   12/6/2011 2:50:14 PM
NO RATINGS
I'm impressed by the breadth of your recent coverage on composites, Ann. I'm wondering if you see new standards emerging out of the FAA as regards composites repair, or will we see industry-standard practices come into play first, which will become de facto methodologies for both repair and recycling?

Ann R. Thryft
User Rank
Blogger
Re: Is this just a transition period?
Ann R. Thryft   12/6/2011 2:49:46 PM
NO RATINGS
Rob, that's the $64,000 question. I think the answer here is also 'both." Composites are definitely moving forward in aerospace, as shown by all the aircraft makers using them in greater amounts. And detection of at least certain types of damage is difficult, but apparently not impossible. 

Ann R. Thryft
User Rank
Blogger
Re: Composite Aircraft Repair Advances
Ann R. Thryft   12/6/2011 2:45:31 PM
NO RATINGS

I think the answer is a bit of both. Beth, the industry apparently has been working on solving this problem along with the FAA. At least, that's what they all tell us. But it's quite difficult to find out any details. And that's where ScotCan's point comes in. As the report delineates, industry has been extremely secretive regarding the details about their materials--the type of details which must be well known for determining when and how to repair--in the name of trade secrets. 


Page 1/2  >  >>


Partner Zone
Latest Analysis
Do you see a perfectly good design and still insist on changing it? You might be an engineer.
A bold, gold, open-air coupe may not be the ticket to automotive nirvana for every consumer, but Lexus’ LF-C2 concept car certainly turned heads at the recent Los Angeles Auto Show. What’s more, it may provide a glimpse of the luxury automaker’s future.
Perhaps you didn't know that there are a variety of classes, both live and archived, offered via the Design News Continuing Education Center (CEC) sponsored by Digi-Key? The best part – they are free!
Engineer comic Don McMillan explains the fun engineers have with team-building exercises. Can you relate?
The complexity of diesel engines means optimizing their performance requires a large amount of experimentation. Computational fluid dynamics (CFD) is a very useful and intuitive tool in this, and cold flow analysis using CFD is an ideal approach to study the flow characteristics without going into the details of chemical reactions occurring during the combustion.
More:Blogs|News
Design News Webinar Series
12/11/2014 8:00 a.m. California / 11:00 a.m. New York
12/10/2014 8:00 a.m. California / 11:00 a.m. New York
11/19/2014 11:00 a.m. California / 2:00 p.m. New York
11/6/2014 11:00 a.m. California / 2:00 p.m. New York
Quick Poll
The Continuing Education Center offers engineers an entirely new way to get the education they need to formulate next-generation solutions.
Jan 12 - 16, Programmable Logic - How do they do that?
SEMESTERS: 1  |  2  |  3  |  4  |  5  |  67


Focus on Fundamentals consists of 45-minute on-line classes that cover a host of technologies. You learn without leaving the comfort of your desk. All classes are taught by subject-matter experts and all are archived. So if you can't attend live, attend at your convenience.
Learn More   |   Login   |   Archived Classes
Twitter Feed
Design News Twitter Feed
Like Us on Facebook

Sponsored Content

Technology Marketplace

Copyright © 2014 UBM Canon, A UBM company, All rights reserved. Privacy Policy | Terms of Service