Prediction of the performance of structural power composites

Structural multifunctional composite materials are a novel class of materials with the ability to perform various non-structural functions in addition to their structural role, for example, sensing and actuation, thermal and electrical transport, energy harvesting and storage, structural health monitoring and self-healing. The benefits of these technologies include improved reliability and lifetime, reduced component count, and reduced emissions in transport applications due to volume and weight saving and associated system level efficiency gains. Multifunctional composite materials and structures are presently drawing much attention in the aviation industry, where conventional structural composite technologies are now reaching maturity, and where it is recognised that emerging disruptive technologies, such as multifunctional materials, will be vital for future-proofing aircraft against increasingly stringent emissions goals. Adoption of these materials, however, implies a step change in engineering design philosophy and manufacturing practices, and a vast amount of research must first be undertaken to develop the material systems and technology frameworks.
On going research efforts led by Imperial College London focus on the development of multifunctional materials and devices which combine structural and electrochemical energy storage functionalities in the form of a structural supercapacitor. The devices are constructed as a hybrid fabric reinforced composite and employ unusual constituents such as carbon aerogel nano-reinforcement and a biphasic multifunctional matrix system, which pose unique implementation challenges. As is common in the field of multifunctional composites, development of the constituents and devices has been exclusively experimental. In these early stages of development total reliance on empirical research can be not only be time-consuming and expensive, but also impractical, since many of the constituents are still under development and therefore continually changing, and only limited quantities are available.
The focus of this PhD project is the development of computational finite element models to predict the performance of structural supercapacitors and to complement empirical research in the design and optimisation of the material for enhanced multifunctional performance. This is in line with the current shift across the engineering industry away from 'prototype and test' and towards 'model and simulate' design approaches. Establishing simulation tools which can accurately predict the mechanical and electrochemical behaviour of the material based on the properties of its constituents will assist in the identification of optimal material microstructures for specific applications, or vice versa, understanding the material's manufacturability and performance limits, and encourage the material's commercial adoption by demonstrating a predictable in-service response. Additionally, development of a multi-physics modelling framework to simulate the mechanical and electrochemical responses simultaneously will provide an integrated approach to multifunctional optimisation and means to investigate possible electro-mechanical coupling. To the author's knowledge there are no such published multi-physics modelling studies in either conventional supercapacitors, or structural supercapacitors, making the proposed work novel. The project is formed of two work packages. Work package 1 will focuses on development of realistic finite element models of the devices at meso-scale and prediction of elastic properties and damage initiation. Work package 2 will couple the mechanical model with an electrochemical model and establish a framework for multifunctional optimisation.