Koratkar said the new crack detection method should eventually be more cost effective and more convenient than ultrasonic sensors commonly used today. His sensor system can also be used in real time as a device or component is in use, whereas the sonic sensors are external units that require a great deal of time to scan the entire surface area of a stationary structure.
Plus, Koratkars system features a built-in repair kit.
When a crack is detected, Koratkar can increase the voltage going through the carbon nanotubes at a particular point in the grid. This extra voltage creates heat, which in turn melts a commercially available healing agent that was mixed into the epoxy. The melted healing agent flows into the crack and cools down, effectively curing the crack. Koratkar shows that these mended structures are about 70 percent as strong as the original, uncracked structure strong enough to prevent a complete, or catastrophic, structural failure. This method is an effective way to combat both microcracks, as well as a less-common form of structural damage called delamination.
Whats novel about this application is that were using carbon nanotubes not just to detect the crack, but also to heal the crack, he said. We use the nanotubes to create localized heat, which melts the healing agent, and thats what cures the crack.
Koratkar said he envisions the new system for detecting cracks to eventually be integrated into the built-in computer system of a fighter jet or large piece of equipment. The system will allow the operator to monitor a structures integrity in real time, and any microcracks or delamination will become obvious by provoking a change in electrical resistance at some point in the structure.
The system should help increase the lifetime, safety, and cost effectiveness of polymer structures, which are commonly used in place of metal when weight is a factor, Koratkar said. There is also evidence tha
|Contact: Michael Mullaney|
Rensselaer Polytechnic Institute