AN EXPERIMENTAL AND ANALYTICAL INVESTIGATION OF COMPOSITE DRIVE SHAFTS WITH NONCIRCULAR END CROSS-SECTIONS

An optimization methodology is presented for the selection of the end cross-sectional shape of composite torque tube's (drive shafts) with noncircular end geometries. In a typical application, metal inserts are adhesively bonded in the ends of the tubes to allow for torque transmission. The worst case scenario of bond failure with subsequent torque transmission via insert-tube contact is considered. Optimization of the tube end cross-sectional shape under this worst case situation is the goal of this study. Employing facets of elasticity and the finite element method, a two step methodology is established to predict the failure torque of a tube with a range of selected end cross-sections. This methodology is verified through comparison with experimental data. Results obtained from the analytical and experimental studies indicate a spline-like cross-sectional shape as the optimal design. Failure torques on the order of 70% of the circular cross-sectional failure torque are shown to be possible.