Airplane passengers will see a flash, maybe hear a loud noise, and they might even feel a slight bump if lightning strikes the plane. The one thing the passengers won’t experience is unsafe flying conditions because of the improved lightning protection engineered into the aircraft and its sensory components.
When airplanes are struck by lightning, damage is usually confined to instruments, such as aerials, compasses and avionics. Rarely does the body of the plane suffer damage because the outer shell is constructed with conductive fibers that provide a path for the electric current.
The Federal Aviation Administration estimates that on average, lightning hits each airliner in U.S. service once a year, a statistic that fuels the research of Assistant Professor Dr. Ehsan Barjasteh of the Mechanical and Aerospace department. His goal is to develop even better aerospace materials for the outer skin of airplanes, the first defense against lightning strikes.
When lightning hits a plane, it can send currents of roughly 200,000 watts or volts through the outer skin and frame.
“One of my main areas (of research) is to make a conductive composite to use in airplanes for lightning strike protection,” said Barjasteh, who also has worked on developing lightweight polymers and other composites for electrical lines in recent years.
“So, if lightning strikes the airplane, the conductivity of the structure would help the current dissipate, and not let the lightning burn off or make a hole in the wing or wherever the incident happens.”
To further his research, Barjasteh received a 2017 summer faculty fellowship and attended a hands-on experience through the U.S. Air Force Research Lab. He spent 10 weeks at Wright-Patterson Air Force Base in Ohio testing the applications of graphene, a lightweight composite that is the thinnest and strongest of its kind and measures only one atom in thickness.
Barjasteh looked at how to insert layers of graphene in between the outer layers of airplanes. First discovered by British scientists in 2010, graphene is composed of pure carbon and arranged in hexagonal patterns. The atoms are densely packed in a honeycomb crystal lattice, which makes the material strong but lightweight. Although lightweight, it has been noted to have a breaking strength of more than 100 times greater than a steel film of the same thickness.
Barjasteh said the honeycomb structure in graphene would cause electricity to travel in a “Z” pattern and dissipate quickly, which would be useful if lightning strikes a plane.
“We are still at the very earliest stage of this work,” Barjasteh said. “It’s a very new material, so there’s a lot of challenges and not only that, but how do you want to scale it up. That’s another set of challenges, if you want to go to large-scale production.”
“Eventually it will happen, but this is a very new material and since it’s new, a lot of researchers are working on how to make graphene and how to scale it up (for large production, such as airplanes).”
Ehsan’s previous research included the development and optimization of advanced polymer and composite materials and processes, such as toughening advanced composite materials, lifetime prediction and aging, 3D printing of polymers for high-temperature applications, and progressive damage detection and analysis.
But his focus now is on aerospace and creating a safer environment for travelers around the world, one layer of graphene at a time.