Materials Selection for Flywheels Fly Whe Kinetic energy: U=Ia=pR102 Mass 兀R··p er unit mass: U_Ro 3+V Stress:0,8 Ro Maximum energy densit s Want maximum op p(3+v See Fig 10 in M. F. Ashby, Materials Selection in Mechanical Design, Pergamon Press, Oxford, 1992