An Investigation into the Development of Multifunctional Features in Glass-fibre Weft-knitted Structures During and Post Preforming

Abstract

Textile fibre reinforced composite structures have earned their position as a credible material, because of their structural properties as well as the possibility of developing complex designs through the textile preforming process. Despite their structural capabilities, they are prone to damage and the scientific research is trending towards developing advanced multifunctional structures that can outperform their traditional load-bearing role. In this regard, the focal point of the research has been on integrating functional elements within the unidirectional and woven composites. Although, knitted composite structures display high conformability, flexibility, and high impact resistance; their poor mechanical strength place them as the least favourite candidate. This research study is an attempt to incorporate multifunctional features within the glass-fibre weft-knitted preforms, from the perspective of enhancing their functional capabilities. This study increases the prospect of weft-knitted preforms in different sectors such as rigid and flexible composites, as well as wearable technology. The essence of this experimental work relied upon exploring the manufacturing routes and methods for successful integration of multifunctional features, within the glass-fibre preform. Therefore, weft knitting technology has been investigated for the integration of the sensing elements (electroconductive yarns) within glass-fibre preform during the fabric development stage. In this regard, knitting parameters have been explored for the development of rigid and flexible glass-fibre sensing preform fabrics. The electromechanical behaviour of the sensing preform has been analysed as a function of glass-fibre knitted sensor design. It was found that the knitting parameters and the sensing element both significantly influence the responsivity. Similarly, after the knitting phase, multi-walled carbon nanotubes (MWCNT) were employed as functional elements; however, they exhibit agglomeration and poor dispersion. Therefore, an in-depth analysis was carried out to optimise the dispersion process. For this purpose, a robust Matlab based Algorithm was developed to evaluate the degree of dispersion quantitatively. Various dispersion routes were explored in conjunction with the developed image processing technique for optimisation, and high-speed shear mixing was used to prepare MWCNT-epoxy ink formulation that was integrated within knitted preform during Coating and vacuum-assisted resin infusion process. The effect of this integration was evaluated from the tensile characteristics of the MWCNTs-integrated knitted composites. The tensile tests conducted on MWCNT-integrated glass knitted composites, suggested an improvement in tensile modulus by 38 % by employing Coating process and a low viscosity ink.

Date of Award	11 Dec 2019
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Prasad Potluri (Supervisor), Anura Fernando (Supervisor) & Matthieu Gresil (Supervisor)