Self-healing is receiving an increasing amount of worldwide interest as a method to autonomously address damage in materials. The incorporation of a self-healing capability within fibre-reinforced polymers has been investigated by a number of workers previously. The use of functional repair components stored inside hollow glass fibres (HGF) is one such bioinspired approach being considered. This paper considers the placement of self-healing HGF plies within both glass fibre/epoxy and carbon fibre/epoxy laminates to mitigate damage occurrence and restore mechanical strength. The study investigates the effect of embedded HGF on the host laminates mechanical properties and also the healing efficiency of the laminates after they were subjected to quasi-static impact damage. The results of flexural testing have shown that a significant fraction of flexural strength can be restored by the self-repairing effect of a healing resin stored within hollow fibres.

Fused filament fabrication (FFF) 3D printing of thermoplastic polyurethanes (TPUs) offers a unique capability to manufacture tailorable, flexible cellular structures which can be designed and optimised for specific energy absorbing applications. This paper describes the first application of this methodology in the creation and experimental analysis of 3D printed cellular structures, which are capable of undergoing repeated compressions to densification without failure. A parametric study has been undertaken, capturing the energy absorbing capability of hexagonal arrays manufactured from two types of TPU, with relative densities 0.18–0.49. Arrays were subject to compressions at strain rates 0.03–0.3 s− 1 and were capable of absorbing energies over the range of 0.01–0.34 J/cm3, before recovering elastically. Critically, samples attained a maximum energy absorbing ‘efficiency’ of 0.36, which is comparable to that of traditional expanded closed cell polyurethane foams. The energy absorption behaviour of all structures was found to be dependent on strain rate and cell orientation with respect to the compression direction. This study shows the clear potential of FFF 3D printing for the creation of a new breed of cellular architectures, which are not constrained by existing manufacturing principles, offering the designer the capability to create resilient architectures specifically tailored to operational applications and environmental conditions

Autonomic self-healing materials, where initiation of repair is integral to the material, are being developed for engineering applications. This bio-inspired concept offers the designer an ability to incorporate secondary functional materials capable of counteracting service degradation whilst still achieving the primary, usually structural, requirement. Most materials in nature are themselves self-healing composite materials. This paper reviews the various self-healing technologies currently being developed for fibre reinforced polymeric composite materials, most of which are bioinspired, inspired by observation of nature. The most recent self-healing work has attempted to mimic natural healing through the study of mammalian blood clotting and the design of vascular networks found in biological systems. A perspective on current and future self-healing approaches using this biomimetic technique is offered. The intention is to stimulate debate outside the engineering community and reinforce the importance of a multidisciplinary approach in this exciting field.