乘坐直升飞机或搭乘航班的乘客都有过被噪音困扰的经历。北卡罗莱纳州立大学和麻省理工学院的研究人员开发了一种能够植入到飞机上的膜，可以降低穿透机舱的低频噪音。
“这项设计有望用来建造一种牢固的、轻质的而且隔音的结构，”北卡罗莱纳州机械和航空航天工程助理教授也是这篇论文的主要作者Yun Jing说。
飞机设计中机翼和机舱位置使用一种蜂窝结构的轻型材料。这种材料组成了构成机舱大部分结构的地板和天花板。这个蜂窝夹层结构使得飞机更加牢固，而且这种轻质材料也能够令飞机更加省油。
但是这种蜂窝结构在阻断低频噪音(来自飞机引擎的噪音)方面还有待加强。而且添加隔音材料来阻断噪音又会大大增加飞机重量，增加飞机的能耗。
北卡罗莱纳州立大学和麻省理工学院的研究人员已经开发出了一种可能的解决方案。
他们开发了一种轻薄的膜覆盖在蜂窝结构的一侧，就好像一个鼓的外皮。当声波击中薄膜的时候，声音会反弹出去而不是穿透过去。
“这对于低频噪音非常有效，”Jing说。“相比于没有薄膜覆盖的蜂窝板，有薄膜覆盖的蜂窝板都能阻挡100到1000倍的低于500赫兹的低频声音。”
这个膜是用0.25毫米厚的橡胶制成的，而且只增加了蜂窝板总重量6%的。
“这个膜的生产成本低廉，可以由任何材料生产，只要不影响蜂窝板结构的完整性即可，”Jing实验室工作的博士生也是论文的主要作者Ni Sui说。“它可以使飞行经历更愉悦，尤其是对乘坐直升飞机的乘客。”
英文原文：
Lightweight membrane can significantly reduce in-flight aircraft noise
Riding in a helicopter or airplane can be a noisy experience for passengers. But researchers from North Carolina State University and MIT have developed a membrane that can be incorporated into aircraft to drastically reduce the low-frequency noise that penetrates the cabin.
"This design is promising for making structures that are strong, lightweight, and sound-proof," says Yun Jing, an assistant professor of mechanical and aerospace engineering at NC State and senior author of a paper describing the work.
Aircraft designs incorporate light materials with a honeycomb-like structure into their wings and cabins. It's the material that makes up the floor and ceiling of most airplane cabins. The sandwiched honeycomb structuremakes it strong, and the light weight makes the aircraft more fuel efficient.
But these honeycomb structures are very bad at blocking low-frequency noise - like the noise of an aircraft engine. And adding insulation materials to limit the noise would add significant weight to the aircraft, making it much less fuel efficient.
NC State and MIT researchers have developed a possible solution.
They have created a thin, lightweight membrane that covers one side of the honeycomb structure, like the skin of a drum. When soundwaves hit the membrane, they bounce off rather than passing through.
"It's particularly effective against low-frequency noise," Jing says. "At low frequencies - sounds below 500 Hertz - the honeycomb panel with the membrane blocks 100 to 1,000 times more sound energy than the panel without a membrane."
The membrane is made of rubber that is about 0.25 millimeters thick, and adds approximately 6 percent to the overall weight of the honeycomb panel.
"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," says Ni Sui, a Ph.D. student in Jing's lab and lead author of the paper. "It could make flying much more pleasant for passengers -particularly in helicopters."
本篇文章来源于: 中国科技网 www.wokeji.com
原文链接：http://www.wokeji.com/guojipindao/dujiabianyi/201504/t20150428_1104912.shtml
