Advanced materials have increased the capabilities of aircraft relative to aluminum—the status quo material used on commercial airplanes. The 787 was the first commercial airplane to have a structure chiefly constructed of a composite material; the carbon fiber reinforced polymer structure provided the strength of an aluminum airplane with less weight and thereby enabled the 787 to fly farther and more efficiently.
However, this new capability came with a technological challenge: Aluminum, being an isotropic material, is uniformly electrically conductive in all directions. Conversely, CFRP has good electrical conductivity along the length of the fibers, but may have poor conductivity in other directions.
Because airplane wings double as fuel tanks, the wings must protect the potentially flammable environment from be ignited by external threats like lightning.
The 787 design accounted for these conductivity characteristics by layering protection schemes on top of structural elements. However, solutions like this are still confined by the history of applying designs that originated in aluminum aircraft to aircraft manufactured from composite materials.
For future aircraft, advancing our technological understanding will better allow us to take full advantage of advanced materials and methods.
Research being performed in a partnership between Boeing and the King Abdullah University of Science and Technology (KAUST) aims to provide lightning protection in a fundamentally different way from previous designs.
This research is proceeding along two paths that, at first, may seem at odds.
First, we are investigating the physical mechanisms that result in the quenching of deflagration waves. Second, we are investigating minimum electrical current conditions that could result in ignition. Understanding these phenomena is a particularly complex science that requires simultaneous investigation of chemistry, fluid mechanics, thermodynamics and electrodynamics in physical scales that have previously been impossible to measure.
The unique aggregation of multi-disciplinary expertise and state-of-the-art diagnostics makes KAUST an ideal partner for these works.
“These projects develop and apply cutting edge diagnostics in novel facilities to gain fundamental insight into the very real technical issues of flame quenching and ignition phenomena,” describes William Roberts, director of Clean Combustion Research Center at KAUST and professor of mechanical engineering.
Our collaborations have resulted in new data that provide insight into the physical processes that govern combustion behavior to enable tailoring electrical and other properties of carbon fiber reinforced polymer to complement the structural advantages in airplanes and other products. Future aircraft will be designed using a much more holistic approach where the structural elements will either double as protection features or are manipulated to retain the same high level of safety.
By Eddie Kwon and Jason Damazo