Optimum design of hybrid composite multi-ring flywheel rotor based on displacement method

A structure optimum design based on the displacement method has been performed to maximize the energy storage capacity of a hybrid composite multi-ring flywheel rotor. In the process of optimal design, the preload stress generated by interference assembly, the fiber material failure and the delamination between two adjacent rings under high speed rotation are all considered. Four types of the optimal schemes of energy storage capacity, energy per unit mass (EPM), energy per unit volume (EPV), energy per unit cost (EPC) and energy per unit mass and cost (EPMC) are proposed to satisfy the needs of different applications and optimal designs are carried out by using a sequential quadratic programming (SQP). The optimal results show that all composed rings of the hybrid flywheel rotor can nearly reach the limits of strength in both radial and circumferential directions, and simultaneously the rotor is at the critical state of delamination. The radius parameters and the maximum allowed rotational speed of the hybrid composite flywheel are closely related to the optimal schemes. Considering the effects of angular acceleration and gravity on the delamination will result in the decreasing of energy storage capacities for four typical applications.