Analysis of the mechanical behavior of composite and metal rivet fasteners in joining of aerospace structures

With the advancement of modern technologies, the use of thermoplastic composite materials has been steadily expanding across various engineering applications. In this study, the mechanical behavior of thermoplastic composite rivets was investigated as an alternative to metallic rivets in structural joints. The primary objective of the research is to determine the most suitable fastener type for aerospace platforms, where low weight and high strength are critical design requirements. In this context, thermoplastic composite rivets manufactured from carbon fiber reinforced poly-ether ketone ketone (CF/PEKK) were compared with aluminum alloy rivets of equivalent geometry. In the experimental program, single-lap shear test specimens were prepared and subjected to tensile loading. The load–displacement data obtained from the tests were converted into stress–strain curves, enabling a comparative evaluation of the mechanical behaviors of CF/PEKK and aluminum rivets. To validate the experimental results, a finite element analysis (FEM) was conducted on the same test specimen configuration using the OptiStruct solver within the Altair HyperMesh environment. Based on both experimental and numerical findings, it was determined that composite rivets exhibit higher yield strength and greater energy absorption capacity compared to metallic rivets. Additionally, the composite rivets demonstrated a progressive damage pattern, displaying pseudo-ductile behavior during loading. Considering these results, it can be concluded that CF/PEKK composite rivets hold strong potential as a robust alternative to traditional metallic rivets.