9561605 Gorman This Small Business Innovation Research Phase I project will conduct fundamental research into the failure mechanics and fatigue performance of composite materials applied to the high stress rotating environment of energy storage flywheels. Implicit in the work is the premise that manufacturing and/or service induced defects in composite fly wheels are inevitable, and that commercial success requires a comprehensive understanding of the type and extent of defects which may be safely accommodated. A combined program of operational and micromechanical analysis and testing iswill be carried out, leading to both manufacturing quality acceptance standards and methodologies for predicting composite flywheel service life. Unique features of this work are the incorporation of inhomogeneous composite material models into the evaluation of flow criticality and growth, as well as explicit consideration of local loading increments due to flaw growth. Phase I will encompass initial conceptualization of the analysis plus coupon testing. Phase II will continue analytical development including spin test to destruction of several composite flywheels. Phase III will apply the developed methodology to a particular UPS composite flywheel product. The end result of this project will be a database of nominal and intentionally flawed coupon strength and rotor spin tests as well as a computer-based composite flywheel reliability design tool. These data and analyses will be formulated so as to assist designers in choosing among the diverse composite flywheel architectures showing commercial promise. The design tool will also guide choices as to design safety factors, estimated service lives, and operational diagnostic and servicing procedures. This research will redress current deficiencies in the understanding of composite flywheel reliability and service life, which demand either very large design safety factors or exceedingly restrictive standards of fabrication and inspectio n. The results are expensive in either case, diminishing delivered performalce on the one hand, and dramatically increasing scrap rates (and costs) on the other. The development of rational defect acceptance standards and service life predictions will remove one of the most significant barriers to composite flywheel energy storage applications currently pending in the automotive and fixed-base UPS markets.
