If demand for production of next-generation, short-range commercial aircraft is to be profitably met, current methods for composite airframe manufacture must achieve significant increases in material deposition rates at reduced cost. However, improved rates cannot come at the expense of safety or increased airframe mass. This project will enable a fourfold increase in productivity by establishing novel manufacturing techniques that speed up deposition of stiffness tailored material. New continuum mechanics-based forming models will ensure delivery of better products by minimising occurrence of manufacturing defects. In a parallel stream of activity, new methodologies for analysis and design of composite structures in which the ply angle and thickness of fibre-reinforcement is spatially tailored, both continuously and discretely, will reduce the need for stiffening, leading to significant savings in structural mass (by up to 30%) and manufacturing cost (by up to 20%). Potential structural integrity and damage tolerance issues, such as transition in fibre angle and tapering of laminate thickness from one discrete angle to another, will be addressed. The project will engage a multidisciplinary team of engineers and applied mathematicians to develop novel manufacturing and modelling techniques. An embedded university-industry partnership will focus on the creation of new manufacturing and analysis capabilities, supported by fundamental research. Academics at Bath and Exeter will partner with the National Composites Centre and with industrial collaborators that span the airframe supply chain. The project will enable production of high performance composite components at rates suitable for the next generation of short-range aircraft. There are also opportunities for impact in the wider composites manufacturing industry, including automotive and energy sectors.

Smart structures, in which monofunctional devices (e.g. sensors, actuators or batteries) and structural materials are sandwiched together, can provide elegant technical solutions to engineering problems. However, they offer limited space and weight savings: ultimately their efficiency is controlled by the interfaces between the device and the surrounding structure. A radically different concept is one in which the constituents (i.e. fibres and matrices) of the structural material themselves are multifunctional, acting in synergy to give truly multifunctional materials which inherently perform two (or more) functions simultaneously. This proposal focuses on structural supercapacitors, in which the material provides two disparate functions: mechanical load bearing and electrical energy storage. Such devices offer important performance advantages in minimising system weight and volume, and present opportunities for innovative design. It is notable that there are several synergies between energy storage devices and polymer composites: the laminated architecture of such materials mirrors the electrode configuration in supercapacitors. Furthermore, both devices use carbon based reinforcements/electrodes infused with a polymeric matrix/electrolyte. Such parallels provide a strong motivation for wedding these two disparate fields to develop structural power materials. Supercapacitors consist of two high surface area electrodes, an electrolyte and a separator: charge is collected reversibly at the electrolyte/electrode interfaces. Their performance makes them useful as high power sources and, when used in conjunction with batteries, life extension for power sources for electric vehicles. For structural supercapacitors, there are two multifunctional components: a structural reinforcement/electrode, and a structural separator/electrolyte. Through our research in this field we have identified three critical challenges for structural supercapacitors: we will address these in this proposal. We will significantly improve how much electrical energy these devices can store (i.e. energy density), how quickly they can be charged or discharged (i.e. power density) and their mechanical performance. To improve energy density, we will develop reinforcements/electrodes with increased surface areas and electrochemical activity. In parallel, we will formulate matrices/electrolytes which are stiff and robust, thus giving enhanced mechanical performance, but with greater ionic conductivity, and hence power densities. In bringing the best constituents together to form multifunctional composites, we will exploit both existing architectures, developed in our previous work, and develop new ones. The project will culminate in demonstration of the best devices through fabrication and testing of industry inspired components. Once mature, this class of multifunctional structural energy storage materials will have a huge impact on applications such as aerospace, automotive and portable electronics. For instance, imagine future tablet computers with no batteries, in which the electrical energy is stored in the casing material. Consider electric cars, in which the bonnet, doors and roof store all the energy to power the vehicle. Meeting such ambitions will have a profound effect on future engineering structures and will inspire others to work in this exciting field.

Breakthroughs in the development of new materials have historically been achieved largely by trial and error. My vision is that there is a new generation of advanced hierarchical materials that has never been addressed and can be achieved by design. This new generation draws inspiration both from recent experimental observations in existing materials and from biomimetics, and is made possible by recent advances in modelling and manufacturing. The main challenges faced by today's composites industry include (i) damage tolerance, (ii) manufacturability and (iii) sustainability. I argue that (i) hierarchical micro-structural designs for composites will be more damage tolerant and achieve over 100% increase in fracture toughness, (ii) that hierarchical discrete carbon-fibre systems will simultaneously address manufacturing and performance needs of the automotive industry, and (iii) that recycled carbon fibres will find a high-value market as semi-structural parts by also exploiting hierarchical architectures. My proposal is to define these hierarchical micro-structures by design and to then develop suitable manufacturing methods to realise them in practice.

We will launch a new CDT, focused on composite materials and manufacturing, to deliver the next generation of composites research and technology leaders equipped with the skills to make an impact on society. In recent times, composites have been replacing traditional materials, e.g. metals, at an unprecedented rate. Global growth in their use is expected to be rapid (5-10% annually). This growth is being driven by the need to lightweight structures for which 'lighter is better', e.g. aircraft, automotive car bodywork and wind blades; and by the benefits that composites offer to functionalise both materials and structures. The drivers for lightweighting are mainly material cost, fuel efficiency, reducing emissions contributing to climate change, but also for more purely engineering reasons such as improved operational performance and functionality. For example, the UK composites sector has contributed significantly to the Airbus A400M and A350 airframes, which exhibit markedly better performance over their metallic counterparts. Similarly, in the wind energy field, typically, over 90% of a wind turbine blade comprises composites. However, given the trend towards larger rotors, weight and stiffness have become limiting factors, necessitating a greater use of carbon fibre. Advanced composites, and the possibility that they offer to add extra functionality such as shape adaptation, are enablers for lighter, smarter blades, and cheaper more abundant energy. In the automotive sector, given the push for greener cars, the need for high speed, production line-scale, manufacturing approaches will necessitate more understanding of how different materials perform. Given these developments, the UK has invested heavily in supporting the science and technology of composite materials, for instance, through the establishment of the National Composites Centre at the University of Bristol. Further investments are now required to support the skills element of the UK provision towards the composites industry and the challenges it presents. Currently, there is a recognised skills shortage in the UK's technical workforce for composites; the shortage being particularly acute for doctoral skills (30-150/year are needed). New developments within industry, such as robotic manufacture, additive manufacture, sustainability and recycling, and digital manufacturing require training that encompasses engineering as well as the physical sciences. Our CDT will supply a highly skilled workforce and technical leadership to support the industry; specifically, the leadership to bring forth new radical thinking and the innovative mind-set required to future-proof the UK's global competitiveness. The development of future composites, competing with the present resins, fibres and functional properties, as well as alternative materials, will require doctoral students to acquire underpinning knowledge of advanced materials science and engineering, and practical experience of the ensuing composites and structures. These highly skilled doctoral students will not only need to understand technical subjects but should also be able to place acquired knowledge within the context of the modern world. Our CDT will deliver this training, providing core engineering competencies, including the experimental and theoretical elements of composites engineering and science. Core engineering modules will seek to develop the students' understanding of the performance of composite materials, and how that performance might be improved. Alongside core materials, manufacturing and computational analysis training, the CDT will deliver a transferable skills training programme, e.g. communication, leadership, and translational research skills. Collaborating with industrial partners (e.g. Rolls Royce) and world-leading international expertise (e.g. University of Limerick), we will produce an exciting integrated programme enabling our students to become future leaders.