Pull-off strength assessment of co-consolidated AS4/PEEK T-joints

Various joining methods are available for composite structures, with anticipated benefits for the most obvious way of exploiting the nature of thermoplastic materials: melting and reconsolidation. A proper joint selection and detailed design, however, will require quantitative results obtained in an objective and reproducible procedure. The objective of this paper was to develop benchmark procedures and results for the characterization of joining methods for composite materials. AS4 carbon/PEEK joints (UD tape) were manufactured in T-configurations by autoclave processing. Two types of T-joints were co-consolidated on the skin, from a flat strip with an injection molded nugget (“butt joint”) or from a pre-consolidated T-stiffener, respectively. RTD, CTD and HW experiments were performed on both types of configurations. The pre-consolidated T-stiffeners have a higher pull-off load and more gradual damage development than the flat strip/nugget configuration, at the cost of added mass. Also here CTD and RTD performances are similar, whereas the flat strip/nugget configuration shows no significant strength reduction in HW conditions, against 30% for the pre-consolidated T-stiffener configuration.