Self-healing composites: A review

Self-healing composites are composite materials capable of automatic recovery when damaged. They are inspired by biological systems such as the human skin which are naturally able to heal themselves. This paper reviews work on self-healing composites with a focus on capsule-based and vascular healing systems. Complementing previous survey articles, the paper provides an updated overview of the various self-healing concepts proposed over the past 15 years, and a comparative analysis of healing mechanisms and fabrication techniques for building capsules and vascular networks. Based on the analysis, factors that influence healing performance are presented to reveal key barriers and potential research directions

Sustainable self-healing structural composites

Self-healing composites are composite materials capable of automatic recovery when damaged. They are inspired by biological systems such as the human skin which are naturally able to heal themselves. Over the past two decades, two major self-healing concepts – based respectively on the use of capsules and vascular networks containing healing agents - have been proposed and material property recovery has been enhanced from 60% to nearly 100%. However, this improvement is still not sufficient to allow self-healing composites to be applied in practice because the healing capability varies with many external factors such as ambient temperatures and damage conditions. The key to the practical application of self-healing composites is to promote the sustainability of healing capacity to make the recovery robust. The thesis presents various techniques to enhance the healing capacity of fibre-reinforced composites to realise strong recovery regardless of ambient temperatures or material types. It presents the effects of various popular configurations of vascular networks on the flexural properties and healing performances of fibre-reinforced composites. The thesis demonstrates a design enabling recovery at ultra-low temperatures by using hollow vascular networks and porous heating elements. It also presents a new healing mechanism to repair the broken structural carbon fibres by incorporating conventional healing agents with short carbon fibres which could be aligned in an in situ electric field. The mechanism was also adopted to enable the restoration of the conductivity of a fibre-reinforced composite incorporating a porous conductive element, a carbon nanotube sheet, which could be used as a heating actuator or a sensing component. Thus, the development reported in this thesis have contributed to promoting the sustainability of the recovery of self-healing composites

Research progress in plant molecular systematics of lauraceae

Lauraceae is a large family of woody plants with high ecological and economic value. The tribal and generic division and phylogenetic relationship of Lauraceae have long been contro-versial. Based on morphological and molecular evidence, phylogenetic relationships within the Cinnamomeae, Laureae and Perseeae tribes, also called ‘the Core Lauraceae’, have arisen particular attention. In this review, we comprehensively collated the literatures on the phylogeny of Lau-raceae published in recent years and summarized progress made in molecular systematic researches employing gene fragments, chloroplast genomes and DNA barcodings analyses. We clarified the phylogenetic relationships and main controversies of ‘the Core Lauraceae’, the systemic position of fuzzy genera (Neocinnamomum, Caryodaphnopsis and Cassytha) and the development of chloroplast genome and DNA barcodes. We further suggested and proposed the whole genome analysis and different inflorescence types would be possible to provide more information for further research on phylogenetic relationships and taxonomy of Lauraceae

Designing robust feedback linearisation controllers using imperfect dynamic models and sensor feedback

The paper considers key limitation of the feedback linearisation controller designed for nonlinear systems based on the imperfect nominal dynamics model and sensors. The model-reality differences cause signal leakages in the feedback linearised dynamics. As the leakages are the functions of the process variables, the resulting overall dynamics are again nonlinear with strong additive nonlinearities and the expected decoupling of the system dynamics is missing. In the paper, instead of using advanced control tools, we prove the robustness of the feedback linearisation method can also be significantly enhanced by employing several simple and classical methods cooperatively. For clear description and explanation, the methodology was illustrated based on a two-link manipulator case study, a classical multi-input multi-output coupled nonlinear system. The methods have genetic potential so that they can be applicable to a variety of case study systems and also further developed to become general methodologies