Effect of He2+ ion irradiation on the mechanical properties of automated fibre placement (AFP) CF-PEEK thermoplastics composites.

Carbon fibre-reinforced polyetheretherketone (CF-PEEK) composites have gained significant usage across diverse industries like automotive and aerospace due to their desirable characteristics. These properties encompass recyclability, low density, high strength, wear resistance and thermal stability. The components made from CF-PEEK composites for space applications will be subjected to a high radiation environment due to the incoming cosmic rays, comprising protons, α particles, electrons, γ rays, etc., once they escape the Earth's atmosphere. The ion irradiation of CF-PEEK is accompanied by radiation-induced effects, which drastically change the structure and properties of irradiated material. Since the resistance of CF-PEEK to radiation damage has not been studied extensively, this study aims to understand the effect of high-energy He2+ ions on the microstructure and properties of CF-PEEK composites manufactured using automated fibre placement (AFP) under different processing conditions. The samples have been radiated with 5 MeV He2+ ions using an energy degrader wheel to create a layer with relatively uniform damage. Then, were characterized using optical and scanning electron microscopy and their hardness was evaluated using nanoindentation. It was observed that, irradiation increases the hardness of the fibres in all cases. Also, fibre orientation affects the hardness in a statistically significant manner in both unirradiated and irradiated conditions.

Micromechanical properties of human trabecular bone: a hierarchical investigation using nanoindentation.

The ability to assess the risk of fracture, evaluate new therapies, predict implant success and assess the influence of bone remodeling disorders requires specific measurement of local bone micromechanical properties. Nanoindentation is an established tool for assessing the micromechanical properties of hard biological tissues. In this study, elastic modulus and hardness were quantified using nanoindentation for human trabecular bone from the intertrochanteric region of the proximal femur. These properties were demonstrated to be heterogeneous and highly correlated at the intraspicule, interspicule, and interspecimen levels. The results of this study have important implications for current understanding of structure-function relationships throughout the trabecular bone structural hierarchy.

AFM nanoindentations of diatom biosilica surfaces.

Diatoms have intricately and uniquely nanopatterned silica exoskeletons (frustules) and are a common target of biomimetic investigations. A better understanding of the diatom frustule structure and function at the nanoscale could provide new insights for the biomimetic fabrication of nanostructured ceramic materials and lightweight, yet strong, scaffold architectures. Here, we have mapped the nanoscale mechanical properties of Coscinodiscus sp. diatoms using atomic force microscopy (AFM)-based nanoindentation. Mechanical properties were correlated with the frustule structures obtained from high-resolution AFM and scanning electron microscopy (SEM). Significant differences in the micromechanical properties for the different frustule layers were observed. A comparative study of other related inorganic material including porous silicon films and free-standing membranes as well as porous alumina was also undertaken.