Tackling stress concentrations in polymer composites

: new local approaches

Abstract

This research developed a novel manufacturing method for metal-epoxy Multi-Matrix Continuously-Reinforced Composites (MMCRC) aimed at mitigating stress concentrations in composite materials. The pursued concept substantially differs from any existent approach and offers a number of unique advantages. In particular, this novel approach addresses stress concentrations through local material modifications, without significantly increasing thickness or weight. Additionally, the materials can be produced using conventional consumables and accessible thermal materials.
The method was validated through experimental testing and the mechanisms for improvements are explained through numerical modelling performed with different degrees of fidelity. The modified structural elements exhibited a 15% improvement in strength and a 16.6% increase in failure strain in open-hole tensile tests.
High-fidelity FEA models were developed to investigate the deformation mechanisms and underlying reasons for these improvements. The FEA results show that the butterfly patch demonstrates superior strength improvements in both braided and woven composites, reducing stress in the yarns by up to 40%. This new material offers a practical and scalable approach for enhancing composite structural properties. Future work will focus on refining MMCRC manufacturing, improving the understanding of interface and damage mechanisms, and exploring potential functional applications, such as increased electrical conductivity.

Date of Award	6 May 2025
Original language	English
Awarding Institution	University of Bristol
Supervisor	Dmitry Ivanov (Supervisor), Luiz F Kawashita (Supervisor) & X C Sun (Supervisor)