Novel hybrid co-cured carbon/glass fibre composite joints for safety critical structures

Effectively integrating composite materials with different physical and mechanical properties requires novel joining techniques to be developed. In this paper, novel co-cured joints between conductive and dielectric composite materials have been developed for multifunctional load-bearing antenna applications. Joints were fabricated using unidirectional prepregs of carbon/epoxy and glass/epoxy and loaded monotonically to failure in uni-axial tension. Ply rupture and interfacial pull-out were the predominant failure modes observed during experimental testing. Analytical and computational models were developed for predicting joint strength and quantifying the effect of joint length. The analytical models accurately predicted the joint strengths when the joint length was either short (<1mm) or long (>>6mm). Accurately prediction of the transition region between shot and long joint lengths was achieved by modeling the joints with high fidelity Finite Element (FE) models. The analytical and numerical analysis methodology developed in this study will enable the efficient design of large integrated radiofrequency transparent windows into a conductive composite structure.