HOME  |  NEWS  |  BLOGS  |  MESSAGES  |  FEATURES  |  VIDEOS  |  WEBINARS  |  INDUSTRIES  |  FOCUS ON FUNDAMENTALS
  |  REGISTER  |  LOGIN  |  HELP
Page 1/2  >  >>
Ann R. Thryft
User Rank
Blogger
Re: Composits durability in aircraft
Ann R. Thryft   11/29/2011 12:03:38 PM
NO RATINGS
 

Thanks, William and Dave. I'd bet a lot of the articles are in NASA Tech Briefs and Composites World. I'm not sure the subject of structural health monitoring would have arisen before, as it's quite new. The GAO report seems to have galvanized the industry and sparked a lot of coverage of the subject.

 

Dave Palmer
User Rank
Platinum
Re: Composits durability in aircraft
Dave Palmer   11/28/2011 4:03:32 PM
NO RATINGS
I'm sure Design News has covered structural health monitoring of composites in the past, but I couldn't find anything in the archive.  However, here's a good article from Composites World which describes some of the many approaches which have been tried.

The fact that there are so many (radically different) approaches to structural health monitoring of composites suggests to me that none of the approaches is perfect; after all, if any one of them were particularly good, we wouldn't be hearing about the others.  But maybe this field is new enough that these things haven't been sorted out yet.

William K.
User Rank
Platinum
Composits durability in aircraft
William K.   11/28/2011 3:50:54 PM
NO RATINGS
None of the articles are recent, but they were in mainstream publications like Design News and Machine design. Some of them may have appeared in NASA Tech Briefs. The common thread of most articles is that composit parts would include a fiber or a conductor in their construction that would be affected by any strain or delamination in the composite component, and that this effect could be measured by some external system. Glass fibers seem to have had the more recent spotlight as potential stars in the monitoring business, at least that is my recollection. None of the reports went into really extensive details, so I am not able to help much there.  My opinion is that it would hbe a huge challenge to create a composite part and be able to preserve a glass fiber for monitoring purposes. But possibly it could be done.

So now you know as much as I can recall about this means of monitoring the health of composite materials.

Ann R. Thryft
User Rank
Blogger
Re: Composits durability in aircraft
Ann R. Thryft   11/28/2011 12:31:18 PM
NO RATINGS

Actually, composites do have a long history in aircraft, as detailed in this recent DN story:

http://www.designnews.com/document.asp?doc_id=235863&

The were first used in military aircraft, though they've been used in commercial aircraft for nearly as long. The difference in the Dreamliner and other recent planes, such as the Airbus 350, is the sheer amount of composites in the plane, and the amounts in primary structures, ie, wings and fuselage.

As to methods for monitoring their health, I'd like to know more about them, too, since that seems to be a key point in the GAO report. William, can you tell us more about what those methods are, or point us towards some of those articles?


William K.
User Rank
Platinum
Composits durability in aircraft
William K.   11/24/2011 10:54:29 AM
NO RATINGS
Composits do have a bit of history, just not in aircraft, it seems.

I know that for many years I have read about methods for monitoring the health of structural composits that have used a variety of fibers embedded into the composite parts during fabrication. All of the articles claimed that this method was wonderful and quite an improvement upon anything else that had ever been done. So the question becomes one about the actual utilization of these methods of monitoring composite health. Are the methods as good as originally claimed? Do these methods work at all? Are these methods just expensive enough that they are not utilized at all? Does anybody else recall reading all of those wonderful articles? Would anybody have any actual experience with this monitoring approach?

It would be good to hear some comments from those closer to the product than I am.

Ann R. Thryft
User Rank
Blogger
Re: What happened in 20 years?
Ann R. Thryft   11/15/2011 3:00:08 PM
NO RATINGS
Thanks Dave, that's a good summary of the problem. It's only field testing that will show up certain types of problems. A lot of research on very similar materials for military planes exists, but the key word is similar; they're not identical.

Dave Palmer
User Rank
Platinum
Re: What happened in 20 years?
Dave Palmer   11/10/2011 3:38:56 PM
NO RATINGS
Of course previous research is still applicable - but the world of civilian aircraft is very different from the world of military aircraft in terms of duty cycle, inspection frequency, and design lifetime. (The same goes for racing vehicles as compared to street vehicles).

You can do all the research and testing you want, but the only way you really know whether your design works is by putting it out in the field for a long period of time.  This is basically what the GAO report is pointing out.

R.A.Richter
User Rank
Iron
Re: Cost of composites
R.A.Richter   11/4/2011 11:39:46 AM
NO RATINGS
Composites have been used in race cars and racing sailboats for a long time.  Sailboats in many cases have been exstensivly insrumented (particularly during an Americas Cup cycle) to understand fatique cycles and degredation.  There are many carbon fiber based racing sailboats now approacing twenty years old.  These have been subject to high slamming loads, structural stresses and extensive UV/atmospheric exposure.  It would seem that some of the research would certainly cross over into the aviation field.  I also seem to remeber when working on the F14 in the early 1970s that there were a number of Boron composit pieces.

TJ McDermott
User Rank
Blogger
What happened in 20 years?
TJ McDermott   11/4/2011 9:33:47 AM
NO RATINGS
My very first job out of college was in the structural test lab of a military aircraft company.  I got to perform fatigue tests on graphite/ epoxy composite hat / skin sections, and residual strength tests on battlefield damage and subsequent repair.

I know all the other aircraft companies were doing the same type of tests at the time.  Is all of this data unusable?  I'm puzzled why there seems to be a gap in the data as described in these articles.

Ann R. Thryft
User Rank
Blogger
Re: Cost of composites
Ann R. Thryft   11/3/2011 5:10:09 PM
NO RATINGS
Thanks, Alex, that's a good question. For carbon fiber-based composites, the figure I saw quoted most often was that virgin fibers cost about 10 times as much as their recycled equivalents. Since virgin fibers cost more than $10,000 per ton, recycled fibers would represent quite a cost savings. 

Page 1/2  >  >>


Partner Zone
Latest Analysis
An Israeli design student has created a series of unique pieces of jewelry that can harvest energy from default movements of the body and even use human blood as a way to conduct energy.
Made By Monkeys highlights products that somehow slipped by the QC cops.
Artificially created metamaterials are already appearing in niche applications like electronics, communications, and defense, says a new report from Lux Research. How quickly they become mainstream depends on cost-effective manufacturing methods, which will include additive manufacturing.
New software from Carnegie Mellon allows 2D objects -- digital photos, old photos, and even paintings -- to be manipulated in 3D using models found online.
Sharon Glotzer and David Pine are hoping to create the first liquid hard drive with liquid nanoparticles that can store 1TB per teaspoon. They aren't the first to find potential data stores, as Harvard researchers have stored 700 TB inside a gram of DNA.
More:Blogs|News
Design News Webinar Series
7/23/2014 11:00 a.m. California / 2:00 p.m. New York
7/17/2014 11:00 a.m. California / 2:00 p.m. New York
6/25/2014 11:00 a.m. California / 2:00 p.m. New York
5/13/2014 10:00 a.m. California / 1:00 p.m. New York / 6:00 p.m. London
Quick Poll
The Continuing Education Center offers engineers an entirely new way to get the education they need to formulate next-generation solutions.
Aug 18 - 22, Embedded Software Development With Python & the Raspberry Pi
SEMESTERS: 1  |  2  |  3  |  4  |  5  |  6


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.
Last Archived Class
Sponsored by igus
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