Future Jet Engines May Be Plastic, Researchers Say

In the aerospace industry, the quest continues for the ideal material -- one that is "light as a feather but stiff as a board" -- for building aircraft, says Dr. Samit Roy, an assistant professor of mechanical engineering and aerospace engineering and engineering mechanics at UMR and a senior investigator at UMR's Rock Mechanics and Explosives Research Center. In recent years, the military has used strong, lightweight carbon-reinforced composite materials for aircraft fuselages, wings and other parts, Roy says.

"They boost performance because they're a lot lighter but stiffer than steel," he adds. They also do not reflect radar well, making these materials indispensable for use in aircraft that rely on stealth technology, such as the F-117 fighter and the B-2 bomber.

Now, the government is looking at whether those same materials can be used as components for the jet engines that power those aircraft. Through a $448,671 grant from Pratt & Whitney Aircraft, Roy will help determine how well such materials hold up under adverse conditions.

Roy and Dr. Lokesh Dharani, associate dean of UMR's School of Engineering and a professor of mechanical and aerospace engineering and engineering mechanics, will test fiber-reinforced composite materials under various conditions. They will then use the data from these short-term laboratory tests and run mathematical models to predict how the materials might hold up over a 15-year period.

The research, which began last July and will continue through October 1999, is being conducted through NASA's Advanced Subsonic Technology (AST) Program. UMR is one of three universities involved in the research with Pratt & Whitney. The others are Georgia Tech and Virginia Tech.

Pratt & Whitney is the leading designer, developer and manufacturer of gas turbine engines for commercial, military and general aviation aircraft.

The researchers will test panels of the composite materials in UMR's Graduate Center for Materials Research, where Dharani is a senior investigator. They will subject the materials to various temperatures and other environmental conditions, simulating circumstances a military aircraft might find itself in on a regular basis. An aircraft might be parked on a tarmac in sweltering heat and humidity one minute, and taking off for the cold and dry conditions of high altitudes the next, Roy says.

The researchers also will test the composite materials for aging. When polymer materials age, Roy says, they tend to become brittle.

Polymer-based composite materials are similar to plastic. "To use polymer technology in an engine is groundbreaking," Roy says. He adds that the advances in polymer science make it realistic to test these materials for possible use as components in "the most hostile environment of all," the jet engine.

"Polymer technology has been advancing rapidly," Roy says, "and there are polymers that can sustain very high temperatures over short periods of time.

"What we don't know yet," he adds, "is how those materials perform over longer periods of time. That's what our research will address."