Segway's Wyer used Ansys to spot stress and fatigue "hot spots" in numerous components. On the wheel model, for instance, the software predicted load conditions it would see in regular usage. The predictions were verified by physical tests.

 

The Segway HT chassis has to carry a 250-lb operator and serve as the housing for motors, batteries, transmission, and electronic components. The unit also had to be lightweight, so there was a weight limit on the housing as well.

Engineers designing an unusual two-wheel electric scooter say Ansys/Multiphysics, from Ansys Inc., Canonsburg, Pa. (www.ansys.com), was key to solving knotty design problems because it meshed and analyzed complex geometry without difficulty.

Engineers with Segway LLC, Manchester, N.H. (www.segway.com), also say the FEA program successfully predicted areas of stress and fatigue on numerous components, and then was instrumental in building a fatigue-testing machine. Segway is a two-wheel scooter that uses a complex set of gyros to balance itself and a passenger, even when not moving.

"Because components in the Segway have sudden geometry changes, they have potential for high stress," says Mark Wyer, an analyst with Segway. "For example, the chassis has to carry a 250-lb operator and serve as the housing for motors, batteries, transmission, and electronic components. The unit also had to be lightweight, so there was a weight limit on the housing as well.

One particular area of concern, the connection between the control shaft and chassis, houses the scooter's recharging unit. Design requirements led Wyer's team to produce parts full of "swoopy" curves. Consequently, there was no way to predict performance using pencil-and-paper calculations.Because Wyer's team used the FEA package at the beginning of its design cycle, he anticipates no major changes to the scooter's configuration. It's commercially available this year.

-- Paul Dvorak