Anticipated growth in global air passengers by 90% over the next 20 years presents both challenges and opportunities. High fuel costs and environmental pressures mean there has been a real focus on operating economics and this has led to an unprecedented growth in composite materials, which offer a lightweight alternative. Successful production of carbon composites brings its own challenges however, in that it requires the use of autoclaves to minimise gaps (void defects) in the polymer resin material that encapsulates the fibres. This makes the process costly, energy-hungry and slow. Lower capital and operating costs, flexible processing infrastructure, a broader supply chain and a greener manufacturing process represent the big gains that could be made through development of effective out-of-autoclave (OOA) manufacturing processes. Indeed, the High Value Manufacturing Catapult has recently identified OOA manufacturing solutions as a key area for economic growth to ensure a UK presence in next-generation aircraft wings, aero propulsion technologies, and structural light-weighting technologies necessary to help the government achieve carbon-reduction and emissions targets. This project will develop experimental techniques and numerical tools to simulate void processes, in order to produce improved material designs for composite manufacture in out-of-autoclave conditions. The processes we intend to analyse use semi-impregnated carbon fibre reinforcement, where the polymer is applied in such a way that dry and saturated regions are present at the start of processing. Two processes will be studied: (i) vacuum bag processing, where consolidation is by atmospheric pressure (low pressure slowly evacuates entrapped gasses, suitable for larger parts such as wing skins), and (ii) using a mechanical press (high pressure fast process collapses voids, suitable for smaller parts such as automotive structures). The advantage of a semi-impregnated material format is that toughened polymers with higher process viscosity can be used, and once the modelling approach is established, it can be extended to resin infusion processes with minor modifications to the model geometry and boundary conditions. The first stage of this project is to address a fundamental need to be able to understand and model the processes that form and remove voids, so that these processes may be designed quickly in a cost-effective manner in a virtual environment. Once this jump in understanding is made and suitable tools created, the second stage is to create tailored materials to minimise formation of void defects for either the vacuum or press-based routes using manual and automatic optimisation. With the UK currently boasting a £2.3bn composite market, and looking to grow this to £12bn by 2030, the findings of this research will contribute to a vitally important and growing sector of the UK economy.

To reduce society's dependence on petroleum based non-renewable polymers, large scale utilization of naturally occurring, abundantly available polymers such as cellulose needs to be developed. One of the major challenges in large scale utilization of cellulose from biomass is dissolution and processing of cellulose to prepare downstream products such as high performance textile fibres. The Viscose method is the most common way to manufacture cellulose fibres; however, it is a complex, multistep process which involves use of very aggressive chemicals and requires a large volume of fresh water. In the 1970s, petroleum based synthetic polymer fibres such as polyester and nylon were commercialised and were proven to be more economical than producing cellulose fibres via the Viscose method. Hence, the production of cellulose fibres was reduced from over 1.3 million tons per year in 1973 to 0.4 million tons per year by 2008 (Source: International Rayon and Synthetic Fibres Committee). To overcome this issue of processing of cellulose we are proposing to develop an environmentally benign method of manufacturing of high performance cellulose fibres using "Green Solvents". The proposed research will help develop sustainable and high performance cellulose fibres which can in-principle replace heavy glass fibres (which requires high energy during its manufacturing) and non-renewable polymer precursors used for manufacturing of carbon fibres which are widely used in composites for aerospace, auto, sports and wind energy industries in UK and abroad.

The UK composites industry faces an imperative to prioritise sustainability. The urgent need to reduce impact on the environment and ensure the availability of resources for future generations is critical to securing a prosperous and resilient future. Composite materials are crucial for delivering a Net-Zero future but pose several unique technical challenges. Sustainable Composites Engineering defines a holistic means of achieving environmental neutrality for composite products through production, service, and reuse. It incorporates the pursuit of more sustainable composite materials, with a mission of creating inherently sustainable composite solutions, able to perform in diverse environments, and made using new scientific advances, and new energy efficient, waste-free manufacturing procedures. Our proposed CDT in Innovation for Sustainable Composites Engineering will address the challenges by developing a workforce equipped with the skills to become leaders in the future sustainable economy and support UK industry competitiveness. Our CDT is jointly created by the Bristol Composites Institute, the University of Nottingham and the National Composites Centre (NCC). In addition to the EPSRC funding our CDT is also supported by industry and we have received 27 letters of support from companies in the UK Composites sector: Aerospace (Airbus, Rolls-Royce, Dowty, Leonardo, GKN), Defence (QinetiQ, AWE, BAE Systems), Automotive (Gordan Murray, JLR), Wind Energy (Vestas, EDF-Renewables), Marine (Tods), Rail (Network Rail), Oil and Gas (Magma Global), Hydrogen (Luxfer) alongside material suppliers (Hexcel, Solvay, iCOMAT, SHD), and specialist design and manufacturing companies (Pentaxia, Actuation Lab, LMAT, Molydyn), as well as RTOs (NPL, NCC). The total industrial commitment to our CDT is >£10M, with>£4M from NCC. From this it is clear that our CDT fits the Focus Area of Meeting a User Need. The CDT will provide a science-based framework for innovative, curiosity driven research and skills development to facilitate composites as the underpinning technology for a sustainable future. Critically, the CDT will offer an agile doctoral educational environment focused on advanced competencies and skills, tailored to industrial and commercial needs, providing academic excellence and encourage innovation. The ambitious goal of spanning Technology Readiness Levels (TRL 1-4) will be achieved by having a mix of university-based PhDs and industrially-based EngDs . Fundamental industrial sponsored research will be carried out by PhD students based at the Universities. The EngD students will spend 75% of their time in industry conducting a research project that is defined industry. Students will complete their doctoral studies in four years, the doctoral research will run concurrently with the taught component, so students are immersed in the research environment from the outset. The bespoke training programme demands the critical mass of a cohort. A specific role on our Management Board focuses on maximising cohort benefits to students. The cohort continuity across years will be ensured by a peer-to-peer mentoring programme, with all new students assigned a student mentor to support their studies, thereby creating an inclusive environment to provide students with a sense of place and ownership. Methods for developing and maintaining a cohort across multiple sites will be supported by our previous experience with the IDCs strategy and by: -A first year based in Bristol with students co-located to encourage interaction. -In-person workshops in year 2 credit bearing units and professional activities. -Peer-to-peer individual mentoring, as well as in DBT and credit-bearing workshops. -Annual welcome cohort integration event. -Annual conference and student-led networking. -Internal themed research seminars and group meetings -Student-led training and outreach activities.