Spring constants of filament-wound composite circular rings

Closed-form solutions from complementary strain energy are derived for the spring stiffnesses of mid-surface symmetric, filament-wound, composite circ ular rings under unidirectional loading. A three-dimensional finite element analysis (FEA) including the effects of transverse shear has also been app lied to study the problem. Four +/- 45 degrees and four +/- 75 degrees E-gl ass/epoxy composite rings of odd numbers of covers were tested. Comparisons of the results obtained from the two methods with experimental data are ma de and the results are found to be in good agreement. The FEA prediction of stiffness is always higher than the theoretical result. The relationships between the spring stiffnesses and the winding angles and geometry of the f ilament-wound composite ring are considered and discussed.