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Reliable composite forming experiments are required to characterize composite formability, to aid material development, and to validate process simulations models. Due to practical reasons, however, typically a limited amount of forming configurations is studied. The objective of this study is, therefore, to develop a methodology for obtaining controlled forming results in a wide range of configurations. Press forming experiments using a dome geometry were used to explore the formability of two commercial unidirectional thermoplastic composite materials. A variety of forming configurations was employed by changing the blank dimensions and layup. The observation of wrinkling defects was simplified by leaving an additional 3 mm tool gap. Blank width and layup had the most influence on the wrinkling severity, followed by blank thickness and length. Quasi-isotropic layups were found to produce wrinkles in nearly all cases, confirming a difficulty in general to form double curved parts. The size and number of wrinkles in these layups were found to change with the stacking sequence. Cross-ply layups showed better formability, but significant wrinkles were still observed depending on the orientation of the blank relative to the layup. The formability experiments using a dome geometry provided a reliable methodology for controlled forming results in many configurations using a generic toolset. Additionally, a comprehensive comparison of formability for two commercial thermoplastic UD materials in a variety of scenarios was provided.

Design and Manufacture of Structural Composites provides an overview of the main manufacturing challenges encountered when processing fibre-reinforced composite materials. Composites are unique in that the material is created at the same time as the structure, forming a very close link between the constituents, the manufacturing process and the resulting mechanical performance. This book takes an in-depth look at material choices and the intermediate steps required to convert different fibre and matrix combinations into finished products. It provides an insight into recent developments for each of the manufacturing processes covered, addressing design, cost, rate and mechanical performance. Topics covered include an introduction to composite materials, material preforming and conversion, moulding, digital design and sustainability, which addresses waste reduction, disassembly and fibre recovery. This book has been developed primarily as a teaching resource with contributions from leading experts in the field. The content has evolved from courses given by the authors to mechanical engineering and materials science students, at both undergraduate and postgraduate levels. It also draws upon experience gained during research projects and from leading industry experts. It therefore provides non-specialists with a valuable introduction to composite manufacturing techniques, helping to determine the most suitable manufacturing routes and to understand the challenges associated with the production of high-performance composite components.

In the over-braiding process, friction at the interlaced points strongly affects the final fibre orientation of the preform [1]. In addition, the frictional behavior appears to be more complex when lubrication agents are applied to the yarn in order to improve processing. This work presents a methodology to investigate the frictional behavior of carbon yarns to better understand the sliding contact mechanisms at yarn levels. The method enables measuring the coefficient of friction as a function of the normal force and inter-angle (the angle between yarns) for both dry and wet conditions. The stick-slip phenomenon is captured well by the method. The results show a strong effect of the inter-angle and the normal force on the friction coefficient. Due to the additional contribution of the capillary force, the friction coefficients of the yarns lubricated with water spray are consistently higher than that of the dry yarns. A model is proposed to capture the influence of anisotropy, normal force and capillary effects on the friction between the two yarns. The model is demonstrated to be capable of accurately predicting the contact force and the coordinates of the contact point.

The emergence of SARS-CoV-2 variants raised questions regarding the durability of immune responses after homologous or heterologous boosters after Ad26.COV2.S-priming. We found that SARS-CoV-2–specific binding antibodies, neutralizing antibodies, and T cells are detectable 5 months after boosting, although waning of antibodies and limited cross-reactivity with Omicron BA.1 was observed.