Everyone knows that Thomas Edison created the modern lightbulb. But it’s a lesser-known Edison discovery — tied to the bulb’s birth — that’s now enjoying the limelight.
In 1879, the inventor and GE founder exposed thin slices of bamboo to scorching heat at his lab in Menlo Park, New Jersey. The cellulose inside the bamboo quickly carbonized, transforming the splinters into the first carbon fibers. Edison used the fibers, which could conduct electricity and handle intense heat, as filaments in his early lightbulbs. But when his engineers invented the modern tungsten filament in 1906, carbon fiber was quickly forgotten.
It remained dormant for the next 80 years, until NASA engineers rediscovered the material in the 1960s. They were seeking an edge in the space race with the Soviet Union, and carbon fiber’s combination of toughness and light weight made it an ideal space-age material.
Designers were soon crafting composite parts made from “prepregs,” layers of carbon-fiber mats impregnated with resin. These parts were tougher, stronger and lighter than steel and aluminum alloys. Composites quickly started replacing metals in the fuselage and other structural parts of cars, planes and missiles.
Today, BMW and Tesla Motors cars have carbon-fiber bodies, and there are carbon-fiber golf clubs and tennis rackets. Up in the sky, Boeing and Airbus build large portions of their next-generation planes, the Dreamliner and the A350, from the material.
But few companies went further than the one with Edison’s pedigree. GE spent several decades developing a version of carbon-fiber composites that could replace the metal fan blades at the front of jet engines to make them lighter and more efficient.
“We planned to replace titanium with what is essentially plastic,” says Shridhar Nath, who leads the composites lab at GE Global Research. “This was a huge, expensive and risky project. We were starting from scratch and we did not know how carbon-fiber blades will respond to rain, hail, snow and sand, and the large forces inside the engine.”
The bet paid off. It allowed GE engineers to shed hundreds of pounds from the fan and build the GE90, the world’s most powerful jet engine; the GEnx for the Dreamliner and Boeing 747-8 aircraft; and now the GE9X, the world’s largest jet engine, whose diameter matches the width of a Boeing 737.
Where the GE90 has 22 blades and the GEnx holds 18, the GE9X will have only 16, even though it is the largest engine of the three. That’s because the blades will feature several new components, says Nick Kray, a consulting engineer for composite design at GE Aviation. They will use stiffer carbon fibers, so GE can make them longer and thinner. Their trailing edge will be made from a special structural glass-fiber composite that can better absorb impact energy. “Carbon fiber is very stiff and not that flexible, so when a bird or something else hits the blade, it creates a shockwave deep inside it,” Kray told GE Reports. “But the glass composite can deform better and deflect stress on the blade.”
GE engineers are already looking for new applications. They are experimenting with carbon-fiber wind turbine blades, riser pipes for the oil and gas industry, and patient tables for X-ray and CT machines that are transparent to radiation and improve image quality. “Over the next 15 years, you are going to see carbon fiber explode across areas where we have not seen them before,” Nath says. “Everybody is interested in reducing weight and increasing strength. That’s what carbon fiber composites got.”