On the Structural Behavior of Mechanically Fastened Joints in Composite Structures

This paper will summarize the results of analytical and experimental studies which have been carried out over a number of years, beginning with work previously reported at the Second Conference on Fibrous Composites in Flight Vehicle Design (1974). Analytical approaches including boundary collocation and finite element methods have been developed to deal with important features of pinned or bolted joints. Experimental results included failure studies of pin-bearing test coupons to explore the parametrics of joint geometry, and moire studies to investigate nonlinearity in 0/90° and ±45° layups. The discussion will cover: effects of edge distance and width in single-fastener lugs; comparison of single-fastener and parallel-fastener configurations; methods of achieving equal load distribution in series-fastener configurations; nonlinear interactions between bypass loads and fastener loads; behavior of hybrid materials; application of the Nuismer-Whitney approach for net section failure, and effects of nonlinear response in 0/90° and ±45° laminates.