A new paint made of power plant waste and carbon nanotubes can automatically detect structural faults, alerting authorities before damage occurs. It could be a cheaper, easier way to monitor facilities like bridges, mines and even wind turbines.
It's made from aligned carbon nanotubes, which can carry an electric current, and fly ash, which is a byproduct of coal burning. The paint can be sprayed onto any surface, and electrodes are attached to it, according to developers at the University of Strathclyde in Glasgow. If the nanotubes bend, their conductivity will change, which will be detected by the electrodes. Small wireless transmitters placed throughout the structure would receive data from the electrodes. If they detect a change in conductivity, this would be considered a sign of a defect in the structure. Then the system could conceivably alert the company or government body responsible for maintaining said structure.
This would be much cheaper and simpler than current monitoring methods, Strathclyde scientists said — currently, wind turbine foundations are inspected visually, and bridges and tunnels only have monitoring networks in certain areas, not throughout the whole structure. Early defect detection could be cheaper to repair, not to mention safer.
A network of electrode-embedded nanotubes doesn't sound inexpensive, but the researchers say it would be cheap — one percent the cost of alternative inspection methods — in part because of the fly ash component. Fly ash is a byproduct of coal combustion and it's generally stored at power plants and landfills or it's recycled. The nanotube paint could be one new use for it. It also lends the paint some added durability, which means it could last in a wide range of environmental conditions.
For now, the electrode transmitters would be powered by batteries, but other designs could incorporate solar panels, piezoelectrics or other energy-harvesting technology, the researchers say. Strathclyde Ph.D candidate David McGahon and civil engineering professor Mohamed Saafi have built a prototype and it was shown to be effective, according to a Strathclyde news release. They plan to carry out larger-scale tests in Glasgow in the future.
[via Science Daily]
While very high tech, this bears amazing resemblance to the process of magna-fluxing that has been around for nearly 100 years. This new process is probably more precise than MF but it still is a surface rendered test and like MagFlux can't detect internal voids or fractures. It will probably be cheaper than an MagFlux machine though.
I agree that it’s probably still a surface only test, but I doubt that it’s any more precise, the real benefit is that it would be a continuous test, and may be able to detect faults as soon as they happen, instead of the annual inspection. But I also doubt it would save any money from an inspection standpoint, I would bet anyone employing this method would still have an annual inspection, because relying on an automatic inspection system seems dangerously negligent. There are too many defects that can only be found by a competent inspector, even if they are only using a visual NDE method.
NANOTUBES DID IT AGAIN !!! ^^ (c)
bored? lets go mine the stars... ^^
Another question is how sensitive is this way of measuring. Would it detect the bending of a bridge because of wind because nanotubes are small and if bending them changes conductivity then a small amount of bending might be all that is required to raise alarm.
I saw the picture at the lead of this story and my jaw dropped. I had "Professor" Saafi during college, I use the term loosely. While I would concede that he is capable in a research laboratory, He is utterly worthless in a classroom. This guy has no business wasting the tuition money of college students by "teaching". Lock him a lab, pay him as a tech, No tenure, no classrooms. I am glad my university's leaders took the advice of the students and canned him.
Here is a first hand example that I believe many PopSci readers will relate to: In a construction engineering course, a student asked Saafi if, for a calculation, we should use the nominal dimensions of lumber or the actual. eg. 2x4 nominal= 1 1/2"x3 1/2" actual. After repeated attempts to explain to him the difference, his reply was "No, No, No...When I go to Home Depot, It say.. two by four."
If you have been tasked with instilling information and marketable skills to a room full of young construction engineers, many of whom work 2 jobs while attending college, or who will be heavily in debt upon graduation, then I believe a basic understanding of real world application is required.
I have so many other examples, but this rant is already running long. ... Thanks, I feel better now.
So as quantum computing is to modern computing, *insert sci-fi ingeniousness here* is to carbon nano-tube technology?
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Wow, I'm sorry, but when I read the misconceptions in this article/comments thread I felt like I needed to clarify things for all the Pop-Sci readers. First off, I work with Civil Engineers on these sorts of projects, and I actually specialize in CNTs. Having said that, there are a lot of things that we don't know yet, but from engineering this is what I can tell you: MagFlux is an interesting technology, but the advantage that the CNT one has is that it is distributed and cheap, so it can cover entire surfaces and be reapplied as necessary. When it comes to internal voids and cracks, the catch with failures is that cracks form on the SURFACE of a material, and that has been proven. A crack on the inside of a material that is homogeneous and isotropic will do nothing, since there is no stress that will cause it to propagate. Unlike in composites, where an internal flaw can cause delamination, concrete does not have the same problems. Therefore, CNTs in this case are very valid. As for the comment about visual inspectors being necessary because otherwise it would be negligent, that's patently false. The problem is that visual inspectors cannot and do not detect all the flaws in comparison to a system that actively and continuously monitors the structure. Finally, when you have wobbling due to winds on a structure, that will come up and be detected on every sensor, and that is an advantage. The point in that case is to compare the electrical signals before and after the wind, the data in the middle is just cut out for failure analysis. As for the wind data itself, it can be used to determine whether the bridge is experiencing dynamic loads that are higher than what it was designed for (if the initial modeling of the bridge did not account for this). Hope this helps!