Gear Production
Issue link: http://gear.epubxp.com/i/155418
F E AT U R E Hybrid gear fabrication steps, showing a composite web that reconnects the hub, web and teeth in such a way as to maintain dimensional accuracy of the teeth. This was done by placing the hub into the center of a tooling fxture that featured a fat steel plate with a circular cutout the same diameter of the gear's web. Composites in Hybrid Gears Replacing steel with carbon fber composites yields promising results. t goes without saying that the heaviest components on any aircraft are easy targets of weight reduction. It also goes without saying that any effort to reduce weight on an aircraft must not compromise reliability or safety. On a rotorcraft, one of the heaviest modules is the drive system that turns the rotors, accounting for about 10 percent of the total weight of the craft. And the drive system, of course, is a major consumer of gears, which are typically fabricated from steel. The NASA Glenn Research Center (Cleveland, Ohio) has begun an effort to look more closely at material use in gears, and in 2012 reported on evaluations of a hybrid composite/steel gear design that showed the possibility to reduce gear weight by as much as 20 percent without sacrifcing gear performance. The effort was led by Dr. Robert Handschuh at I NASA Glenn, with assistance from Gary Roberts, Ryan Sinnamon, David Stringer and Brian Dykus. They focused their efforts on replacement of steel with carbon fber composites in the web of the gear between the gear teeth and the metallic hub that attaches to the torque-applying shaft. The goal was to fabricate a composite hybrid gear and then test it against its all-steel competitors, checking in particular for vibration, noise and long-term durability. Ultimately, the results proved positive. Testing demonstrates that hybrid gears can operate over a long period of time, with decreased weight, and, given the right manufacturing processes, less noise and vibration. Fabrication The hybrid gear NASA Glenn devised was September 2013—23