Multi-level analysis of low-cost Z-pinned composite joints

In the framework of the EU program ALCAS (advanced low-cost aircraft structure), a new Z-pinning technique was developed by EADS Innovation Works. It was used to manufacture low-cost Z-pinned junction demonstrators (L and T shaped specimens) typical of aeronautical structures. In order to understand load transfer mechanisms in this kind of assembly, a multi-level analysis was performed. Firstly, tension and shear pin behaviour was investigated as well as pin pull-out from net resin. It was demonstrated that the mechanical transfer is mainly through bonding, even when the pins are twisted. Secondly, an analytical model was proposed which predicts the maximum load capacity of a single pin. Finally this study provides the basis for a design methodology to compute ultimate loads of Z-pinned junctions under complex loading.