Visoelastic Analysis of Composite Flywheels for Energy Storage

Report No. ARL-TR-2610
Authors: Jerome T. Tzeng
Date/Pages: November 2001; 41 pages
Abstract: A viscoelastic analysis has been developed to investigate stress relaxation and creep in a multilayered composite cylinder subjected to rotation. The analysis accounts for ply-by-ply variation of material properties, fiber orientations, and density gradients through the thickness of cylinders. A closed form solution based on the corresponding elastic problem is derived for a generalized plane strain state in a thick-walled, multilayered cylinder. Laplace transform is then applied to obtain the numerical solution of the viscoelastic problem. This report illustrates the derivation of the analytical model and solution procedure. A numerical simulation shows substantial creep and stress relaxation in thick-walled cylinders at an elevated temperature. Viscoelastic effects of composite can result in a drastic change of stress and strain profiles in a cylinder over a period of time, which is critical in terms of structural durability for applications such as energy storage flywheels.
Distribution: Approved for public release
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Last Update / Reviewed: November 1, 2001