Optimal design of hybrid composite flywheel rotors for energy storage

Energy-storage flywheel rotors are preferably made from high-strength and low-density fiber-reinforced polymer composites. In this study the focus was on utility-grade energy storage flywheels. A 3-dimensional numerical model was developed for hybrid composite flywheel rotors. Employing finite element analysis, stresses induced by rotor rotation were calculated. Numerical results were validated using elasticity theory and data from the technical literature. Design optimization was performed in an effort to maximize energy storage capacity and minimize rotor cost. Material properties, fiber orientations, rotor geometry and angular velocity were parameters considered in the optimization process which aimed at either maximizing specific kinetic energy or kinetic energy per unit cost based on maximum stress failure theory. The primary objective was to reduce radial tensile stresses generated during rotor rotation. Different case studies were performed to demonstrate model capabilities. It was shown that the present approach facilitates the development of efficient and cost-effective flywheel rotors.