End-of-life Design for Composite Rotors

The University of Texas Center for Electromechanics (UT-CEM) is developing flywheel energy storage systems for combat and commercial vehicles and also leads the major U.S. Flywheel Safety and Containment Program, a consortium effort of several leading flywheel developers. Safety for high performance composite flywheel systems on combat vehicles presents special challenges that impact the design of all flywheel components, especially the composite rotor and the bearings. This paper will present an overview of the issues and discuss design strategies and solutions applicable to the combat vehicle environment, using the flywheel energy storage system design recently completed under the Defense Advanced Research Projects Agency (DARPA) Combat Hybrid Power System (CHPS) Program as a case study. In particular, the paper will trace basic design and safety strategy, fatigue cycle development, lifetime design approach, and the resulting design margins.