Honeycomb-membrane

North Carolina State University and MIT researchers have partnered to develop a lightweight membrane for aircraft, which can reduce low-frequency noise that enters the cabin.

Made of 0.25mm thick rubber, the membrane can be used with honeycomb-like materials that form aircraft wings and floor and ceiling of cabins.

The membrane, which covers one side of the honeycomb structure, blocks the sound waves from passing through it and bounces them back.

North Carolina State University mechanical and aerospace engineering assistant professor and senior author of project Yun Jing said: "It’s particularly effective against low-frequency noise.

"At low frequencies, sounds below 500Hz, the honeycomb panel with the membrane blocks 100 to 1,000 times more sound energy than the panel without a membrane."

"It could make flying much more pleasant for passengers, particularly in helicopters."

Usually, the honeycomb structures do not block low-frequency noise such as noise of an aircraft engine. Using insulation materials to limit the noise will increase the weight of the aircraft.

The new material adds approximately 6% to the overall weight of the honeycomb panel, researchers said.

Lead author of the paper Ni Sui said: "The membrane is relatively inexpensive to produce, and can be made of any material that does not impact the structural integrity of the honeycomb panel.

"It could make flying much more pleasant for passengers, particularly in helicopters."

NC Space Grant has supported the project.


Image: The membrane can be used with honeycomb-like materials that form aircraft wings and floor and ceiling of cabins. Photo: courtesy of NC State University.