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.\ud 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.\ud 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

FibreChain: characterization and modeling of thermoplastic composites processing

Thermoplastic composites feature the advantage of melting and shaping. The material properties during processing and the final product properties are to a large extent determined by the thermal history of the material. The approach in the FP7-project FibreChain for process chain modeling of thermoplastic composites is presented

Braiding take-up speed optimization - case studies

Circular braiding is a composite material manufacturing process for production of bi- and triaxial tubular preforms that are usually impregnated and cured using Resin Transfer Moulding. The process currently lacks automatic generation of optimum machine control data. Helping to solve this problem, a newly developed geometry-based procedure for take-up speed optimization is applied to various complex mandrel shapes to assess its strengths and weaknesses. As a result, the error of the virtual braid angle could be reduced to a few degrees. However, in order to assess the validity of the generated process settings, it is recommended to take into account the manufacturing constraints regarding the prevention of yarn slack and fiber slip