Rim for use in flywheels for kinetic energy storage

A flywheel for storing kinetic energy and comprising:

• a double spider configuration hub having a dome-shaped top surface and a dome-shaped bottom surface, said top and bottom surfaces being spaced apart and interconnected by a plurality of equally spaced legs forming a circumferential surface of said hub;
• and
• a unitary, thick flywheel rim concentrically supported on said circumferential surface and having a combination of fiber and epoxy matrix wound into a substantially cylindrical configuration having an inner radius R1, and an outer radius R2, and having at said outer radius, R2, a mass density per unit volume .rho.0 and a hoop elastic modulus E.sub..theta..sup.* ;
• said rim also having an integral plurality of concentric radial regions between R1 and R2;
• the mass density per unit volume, .rho. (r), of each said rim region being a linear approximation of a non-linear function of rim radius defined as follows:
• .rho. (r)=.rho.0 (r/R2).sup.-2 ;
• and
• the hoop elastic modulus, E.sub..theta. (r), of each said rim region being a constant substantially equal to the average value within each said rim region of the hoop elastic modulus defined as a function of rim radius as follows:
• E.sub..theta. (r)=E.sub..theta..sup.* (r/R2).sup.1+.nu.
• where
• R1.ltoreq.r=rim radius .ltoreq.R2;
• and
• 0.ltoreq..nu.=constant .ltoreq.0.5.