Patent ID: 6416432
Filing Date: 2002-07-09
Classification: B32B,F16F,Y10T

Abstract:
A sports Racket comprising a frame of an energy absorbing structural laminate, said structural laminate comprising:(a) a first layer of composite material comprising x1 plies; wherein x1 is from 1 to 50; and wherein at least 0.5x1 plies contain fibers arranged in a shape of a continuous curve; wherein said continuous curve is the same or different in different plies; (b) a second layer of composite material comprising x2 plies; wherein x2 is from 1 to 50; and wherein at least 0.5x2 plies contain fibers arranged in a shape of a continuous curve; wherein said continuous curve is the same or different in different plies; and (c) a viscoelastic layer disposed between the first and second layers such that shear strains are substantially distributed in said viscoelastic layer when a load is applied to the apparatus; provided that no more than 0.75x1 plies of said first layer and no more than 0.75x2 plies of said second layer contain fibers arranged in a shape of sine curves in which: (i) angular axes in said 0.75x1 plies and said 0.75x2 plies are substantially parallel and wavelengths and amplitudes are substantially equal; (ii) sine curves within said 0.75x1 plies are substantially in phase, and sine curves within said 0.75x2 plies are substantially in phase; and (iii) a phase difference between said 0.75x1 plies and said 0.75x2 plies is within about 30Â° of 180Â°.