In addition to repairing composites in aircraft structures, figuring out whether they have been damaged in the first place was a top priority in a GAO report that critiqued the growing use of composites.
We have reported before on this site on self-monitoring adhesives that could predict aircraft structural failures. Now GKN Aerospace, one of Boeing's composite aerostructure suppliers, is researching a class of coatings that may make fractures and other damage visible under certain nonvisible wavelengths.
GKN Aerospace has partnered with a UK university in an 18-month collaborative research venture that's in its first quarter, Max Brown, head of engineering at GKN Aerospace's Filton engineering center, told us.
Inspection of composites used in aircraft such as the A350 XWB, shown here in Getafe, Spain, during
initial horizontal tailplane assembly, may be assisted by research into coatings
that will make damage visible at certain wavelengths.
(Source: Airbus)
"Our collaborative coating research is aimed at supplying inspection techniques for the future maintenance and repairability of composites," said Brown. "Today, it may not be immediately obvious to an inspector of composite material as to what level of damage has been experienced, if any. What we envisage is a more intelligent inspection capability. For example, when inspectors are looking at a wing structure, they could look in the right wavelength range, and any areas that have damage above a certain preset threshold will clearly display that damage."
By the end of the program, GKN expects the coating to reach TRL (technology readiness level) 2 or 3. That would indicate that the research team has proven the basic chemistry and would then be able to move to detailed conversations within the engineering community about development for specific applications. "In an additional 18 to 24 months or so, we would probably be approaching TRL 5 or 6." When a technology reaches TRL 6, it's ready for a demonstration -- in this case, a flight trial.
GKN's goal is to design specific microspheres held within a coating. On impact, if damage has occurred, the microsphere capsule wall fractures, and the chemical reactions produce a signature within the coating that is visible at specific wavelengths.
Dave, You just articulated the point that I was trying to make so much better than I did. It does seem like a no-brainer, especially if the technology has been around for a while. I'm wondering what hurdles there were preventing this from being put to use in any significant form prior to now. Or maybe it's that there wasn't a formal market for something like this given that composite materials are just now becoming so dominant in aerospace design.
Thanks, William and Dave, for sharing your experience in this area. It surprises me that using composites as a repair material for aluminum didn't strike anyone as not a good idea, since their properties are so different. To my limited knowledge so far, repair materials for composites are supposed to pretty closely match the material they are replacing.
The whole subject of using coatings to monitor structural health does seem obvious, doesn't it? I notice that Stresscoat does not appear to address composites. The big deal about them is the fact that damage can be invisible, hence the attempts to make it visible under other wavelengths. And yes, you would think that research such as GKN's would have already occurred, and perhaps it has. Theirs was not easy to find, so it's possible there's other such research going on quietly.
Beth, I understand that designing these different coatings is equally simple, whether one coating detects one energy level or multiple energy levels. Creating the actual coating may be a different story, but that wasn't entirely clear. In any case, GKN said it plans to sell the coatings as an integral part of its composite aircraft structural components, not as a separate product line.
Coatings such as Stresscoat have been used in experimental stress analysis for decades. It seems like a no-brainer to use something like this for structural health monitoring. Of course, it's easy to say that something is a no-brainer after someone else has already come up with it. I'm just surprised that nobody came up with something like this sooner.
Thanks for the article Ann! It is great to see this technology being commercialized and incorporated into engineering materials. I was involved in the development of diagnostic coatings which, when excited and viewed under specific wavelengths, provided surface information of temperature, pressure, strain, and cracks. The coatings were applied to the surface of the completed unit for testing. I'm delighted to learn of continued development of both surface and internal coatings during component manufacturing.
One of our biggest surprises came from using composite repair material when applied to traditional metals (aircraft aluminium). Our coatings were used to inspect the performance of a "composite Band-Aid" that could be used to field dress a fatigue crack until the panel could be replaced. The difficulty was that the mechanical performance of the composite material was so superior to the original alloy that the repair site was often a greater point of additional fatigue cracking in the original metal because of the sharp differences between the materials. I imagine things will be better and far superior when all of the components are made out of advanced composites in the first place.
Very cool piece of development and one that would certainly benefit broader use of composites. The idea that a coating could deliver intelligent inspection capabilities is in some ways out there, but then again, in keeping with steady pace of technological advances. In many ways, the development strategy makes perfect sense. Do you have a sense of how difficult or how unique it is to develop a single coating with different signatures that can appear different depending on different energy levels of impact?
Inspired by the hooks a parasitic worm uses to penetrate its host's intestines, the Karp Lab has invented a flexible adhesive patch covered with microneedles that adheres well to wet, soft tissues, but doesn't cause damage when removed.
Engineers at the University of California, San Diego are designing a robotic arm that takes inspiration from the loose, flexible, yet very strong structure of the armored plates on a seahorse's tail.
Researchers at the Missouri University of Science & Technology have designed a new nanoscale material that can transmit light faster than the 186,000 miles per second it usually takes to travel through air.
It has often been said that as California goes, so goes the nation. This spring, the state's wind power is setting energy generation records and solar energy generation is expected to rise sharply during the second half of 2013.
The latest model of Liquid Robotics' Wave Glider autonomous, unmanned marine vehicle (UMV), the SV3, is reportedly the world's first hybrid wave- and solar-power-propelled unmanned ocean robot.
From Dell / Intel® New Paradigms in Design Work Scott Hamilton, vertical market strategist for Dell Precision workstations, 5/2/2013 3
Early in my career, I worked as a draftsman and remember the days of drawing on vellum with numbered pencils and Mylar with plastic lead. This was a fun experience in the sense that I ...
I've been using workstations for more than 10 years and love finding ways to get more performance from my system. With demanding professional applications that require more power each ...
A lasting memory from my first job as an engineer in an auto assembly plant is standing on hard concrete at six in the morning, vending-machine coffee clutched in hand, listening to ...
A quick look into the merger of two powerhouse 3D printing OEMs and the new leader in rapid prototyping solutions, Stratasys. The industrial revolution is now led by 3D printing and engineers are given the opportunity to fully maximize their design capabilities, reduce their time-to-market and functionally test prototypes cheaper, faster and easier. Bruce Bradshaw, Director of Marketing in North America, will explore the large product offering and variety of materials that will help CAD designers articulate their product design with actual, physical prototypes. This broadcast will dive deep into technical information including application specific stories from real world customers and their experiences with 3D printing. 3D Printing is
To save this item to your list of favorite Design News content so you can find it later in your Profile page, click the "Save It" button next to the item.
If you found this interesting or useful, please use the links to the services below to share it with other readers. You will need a free account with each service to share an item via that service.
Tweet This
8 
