3 – The flywheel

Publisher Summary This chapter discusses the various types and characteristics of flywheels. Flywheels often operate for long periods in conditions of low gear efficiency, while high transmission efficiency is vital for the success of a kinetic accumulator. If the speed is to be kept low, the best approach is to use a geometry with the highest possible radius of gyration. In such a case, the use of a massive rim built with high-density materials and connected to the shaft by spokes or by a thin disc is a reasonable choice. If, however, there is no limitation on the angular velocity, small discs with constant stress profile made from low-density, high-strength materials will yield the maximum energy density. The choice of the flywheel material depends largely on the design requirements and on a variety of constraints. If there is no constraint on the peripheral velocity, the main feature is the specific strength of the material. The more usual choices for composite material flywheels are plastic materials reinforced with glass fiber or carbon or aramid fibers.