Exact, integrated and complete solutions for composite flywheels

An integrated general formulation for the analysis and design of flywheel rotors made out of composite material is developed. To have an accurate estimation of stresses in the rotor, all the effects present in the literature and some new ones have been included: axial length (disks vs. cylinders), acceleration (sudden energy releases), hub stiffness and mass (attachment), non-uniform curing (different temperature inside, outside rotor) and moisture absorption (transient, permanent). Through pertinent transformations, these effects are described by a single differential equation that can be directly integrated, giving closed-form expressions for displacements, stresses and failure factors. The new formulation is applied to the study of a standard rotor of the type commonly analyzed in the literature, uni- and multilayer, made out of glass and carbon fiber/epoxy materials. The results are compared with those corresponding to each of the effects, drawing conclusions and design recommendations.