Ultrasonic Spectroscopy of Composite Rings for Space Station Flywheel Rotors

摘要

Flywheel energy storage devices consisting of multiple layered compos-ite materials are being studied extensively for utilization in the Interna-tional Space Station. These composite material systems were investigated with a recently developed ultrasonic spectroscopy technique. The system employs a swept frequency approach and performs a fast Fourier transform on the frequency spectrum of the response signal. In addition, the system allows for equalization of the frequency spectrum, providing all frequencies with equal amounts of energy to excite higher order resonant harmonics. Interpretation of the second fast Fourier transform, along with equalization of the frequency spectrum, offers greater assurance in acquiring and ana-lyzing the fundamental frequency or spectrum resonance spacing. The sys-tem can sweep a range of frequencies from an audible range up to 8 MHz, depending on the material and geometry of the component. Single and multiple layered material samples, with and without known discontinu-ities, were tested to determine how the constituents of a composite material ring system affect the resonant frequency.