Intra-yarn Natural/Synthetic Fibre Hybridisation in Woven Composites: A Two-Scale Analysis with Uncertainty Modelling

Abstract

Natural/synthetic fibre reinforced hybrid composites (NFHCs) are innovative materials that combine the benefits of synthetic and natural fibres through intra-yarn fibre hybridisation. By partially replacing synthetic fibres in traditional fibre reinforced composites (FRCs) with natural fibres, NFHCs achieve comparable structural performance while offering advantages such as biodegradability and accessibility. However, the experimental characterisation of the wide variety of fibre and matrix combinations, fibre volume fractions, and weave architectural variations is both time-intensive and costly. Current computational characterisation tools primarily focus on synthetic FRCs or synthetic/synthetic hybrid FRCs, leaving a gap in the study of NFHCs. This study addresses this gap by developing a twoscale computational framework to investigate the effects of intra-yarn fibre hybridisation, weave architectures, and micro-scale uncertainties on the thermomechanical properties and stress distributions in woven composite laminae. The two-scale approach integrates microscale representative volume element (RVE) models and meso-scale repeating unit cell (RUC) models. A modified random sequential expansion (RSE) algorithm generates random fibre distributions for RVEs, while the open-source software TexGen is used to model weave architectures for RUCs. The framework is applied to a range of hybrid composite systems such as S-glass/PP, flax/E-glass, hemp/E-glass, and basalt/E-glass across various weave architectures, including plain weave, 2/2 basket weave, 2/2 twill weave, 5-harness satin, and 3D orthogonal weaves. Moreover, a stochastic modelling approach incorporating Monte Carlo simulations is employed to account for uncertainties in natural fibre geometry and elastic properties. This enables a detailed analysis of how micro-scale variability influences homogenised properties and stress fields at the micro-scale. The results highlight that yarn-level hybridisation significantly alters homogenised properties, stress fields and thermal residual stress distributions, with the degree of hybridisation and fibre type playing a pivotal role. The results reveal that yarn-level fibre hybridisation can significantly alter the thermomechanical properties of NFHCs, offering the ability to tailor material behaviour for specific applications. While weave architecture has a limited effect on homogenised elastic properties, it notably influences stress distributions. Micro-scale uncertainties, particularly in natural fibre properties, exacerbate matrix stress concentrations, increasing the likelihood of damage mechanisms such as matrix cracking. By leveraging intra-yarn fibre hybridisation and variability modelling, NFHCs demonstrate their potential as sustainable alternatives to fully synthetic composites, particularly in applications where lightweight design, durability and environmental considerations are critical.

Date of Award	16 Dec 2024
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Kali-Babu Katnam (Main Supervisor), Prasad Potluri (Co Supervisor) & Zhenmin Zou (Co Supervisor)