Bolted joint method for composite materials using a novel fiber/metal patch as hole reinforcement—Improving both static and fatigue properties

Several joining methods exist, and these are generally categorized as bolted joining methods, adhesive bonding methods, or hybrids of the two. Over the years several joining techniques have been proposed to improve the load transfer between components. This paper presents a new bolted/pinned joining methods for composite applications. This is done by introducing a new patch-type reinforcement. Both static and fatigue test results are presented and compared with unreinforced bolted joint data. Experimental data shows that significant improvements are obtained for both static and fatigue load conditions when this new joining method is utilized. Different metrics are used in the paper to compare the performance of the presented joining methods with existing methods. These metrics are a load transferring efficiency factor, bearing stress, and percentage improvement compared to a reference sample. For most of these metrics, the presented joining method performs similarly or significantly better than existing solutions. In addition, finite element simulations highlight that the advantage of the presented joining method is that the load is not only carried by compressive stresses above the loaded hole but also by tensile stresses below the hole. Therefore a much more efficient load-transferring mechanism is created with the presented joining method.