Optimal design of press-fitted filament wound composite flywheel rotors

This paper explores the design of press-fitted, cylindrical, filament wound composite flywheel rotor rims using two-dimensional plane stress anisotropic elasticity solutions and an optimization method based on simulated annealing. A method of accounting for residual stresses in press-fitted composite rims is proposed and demonstrated. The starting point for the designs is an open core rotator motor/generator with a pre-determined, fixed pair of concentric rotor rings, upon which several carbon/epoxy rings with different structural properties are press-fitted. For certain assumed sequences of carbon fiber types versus radius, optimal designs are determined with the objective of maximizing specific energy of the rotor subject to constraints defined by expected operating speeds and temperatures as well as material strengths. The optimal solutions suggest that specific energies of 40–50 W · h/kg and tip speeds of 800–900 m/s are feasible with 5–8 press-fitted carbon/epoxy rings.