Dynamic Analysis of Three-Dimensional Composite Tube Shafts

Three-dimensional (3D) composites have good delamination resistance along with high specific stiffness and high specific strength. Composite tube shafts are modeled with different reinforcement architecture such as multi-axial, stitched, knitted, braided, orthogonal woven, interlock and z-pinned. The in-plane elastic properties at different fiber volume fractions of these composites are obtained from the literature. 3D composite tube shafts are modeled with length: 1 m, internal radius: 25 mm and thickness: 4 mm using modified equivalent modulus beam theory formulation. Modal analysis is carried out, and bending natural frequencies are calculated for different 3D composite tube shafts with E-glass, carbon and kevlar fibers and epoxy as matrix materials. The natural frequency reduces with through thickness reinforcement for orthogonal, knitted, z-pinned and stitched composites. Braided composites tube shafts have higher natural frequencies compared to that of other types.