Prediction of the Tensile Load Capability of Co-cured Steel-Composite Tubular Single Lap Joints Considering Thermal Degradation

Co-cured joints composed of composite and steel structures are realized by the excess resin extracted during cure of composite prepreg and the coupling pressure due to residual thermal stresses generated by the difference of coefficients of thermal expansion between the two materials. Although the excess resin from the composite prepreg is less dependent on the environmental temperature compared to conventional epoxy adhesives in which rubber is added to strengthen toughness, the coupling pressure is much dependent on the environmental temperature. In this study, the tensile load capability of co-cured joints composed of carbon fiber epoxy composite and steel adherends was experimentally investigated with respect to the stacking sequence of the composite and the environmental temperature. Also, the stress distributions in the composite were calculated by finite element method, from which the failure index of the composite adherend was calculated considering thermal degradation of the composite. The co-cured steel-composite tubular single lap joint under tensile loads might be applied to hybrid structures such as golf clubs and automotive composite propeller shafts which have a conventional adhesively-bonded joint by epoxy adhesives with fillers between a carbon/epoxy shaft and a metal shaft.