The economics of machining aerospace structural components is fundamentally limited by regenerative chatter and process-damping. Harnessing these two phenomena will lead to enormous productivity gains and superior competitive advantage. For example, a recent project at Sheffield was able to avoid chatter and reduce machining times by a factor of 5, resulting in a multi-million pound contract being awarded to the sponsor. However, current scientific understanding of process-damping is inadequate, so that recent research has resorted to intuition, trial and error, or exhaustive experimental testing. This project aims to overcome these barriers by providing new scientific understanding and engineering tools, and to transfer this technology to the manufacturing community.

The RE-Ba-Cu-O (where RE= rare earth element such as Y, Nd, Sm, Gd, etc.) family of bulk, melt processed high temperature superconductors [(RE)BCO] is the subject of extensive world-wide research due primarily to their potential to trap large magnetic fields. This has been demonstrated spectacularly by the Cambridge Bulk Superconductivity Group, which recently set a new world record trapped field of 17.6 T at 26 K using these materials, breaking the previous world record that had stood for more than 10 years. The Cambridge Group has been at the forefront of research in this area for the past 20 years and, in addition to funding from EPSRC and other government sources, has attracted substantial and sustained industry funding. Bulk (RE)BCO superconductors have reached an important and critical stage in their research and development. Their spectacular field generating properties have high potential for a range of sustainable engineering applications, including flywheel energy storage, motors and generators, magnetic separators, bio-medical applications and magnetic levitation devices. This proposal is for a unique and timely combination of fundamental materials research and the development of practical assemblies to generate practical magnetic fields using bulk superconductors that can be used routinely and commercially in engineering devices for the first time. The main objective of the project will be to shape the magnetic field at low temperatures (50 K and 30 K), where critical current, and hence field generating capability, is significantly higher than at 77 K. Materials to improve the mechanical strength and the thermal conductivity for incorporation in the sample and assembly structures will be developed to obtain optimum performance in high field for samples and assemblies magnetised specifically by pulse magnetisation. It is becoming increasingly likely that rapidly developing cryo-cooler technology will enable practical applications at temperatures below 77 K, and this will drive the development of improved materials and new structures. The single grain, (RE)BCO bulk superconductors developed with improved mechanical strength and thermal conductivity will be incorporated into assemblies of different composite shapes of different (RE)BCO materials to enable the control of magnetic field strength and distribution. The properties and performance of these assemblies will be compared with larger sized, individual samples of comparable surface areas at 77 K where the requirement for mechanical strength is relatively modest. Capability developed during our current EPSRC grant on multi-seeding will further enable the fabrication of multi-seeded, quasi-single grains, whose properties will be compared with an assembly of smaller, closely packed samples of similar sizes. The trapped field and levitation force of assemblies of different (RE)BCO superconductors arranged in different orders will be measured at 77 K and compared with the properties of conventional, single grains of the same size. The project, which will continue to support outreach in UK school, colleges and universities, benefits from strong financial support of major international industrial collaborators, including the Boeing Company, Siemens and Bio-med (UK).

Composite materials, such as those based on carbon and glass fibre reinforced polymer play an important role in driving global decarbonisation, through corrosion resistant and high-performance products and light-weighting sectors such as transport that lead to improved fuel economy and so reduce emissions. Our proposal targets sustainability of high value composite components, through embedding ultra-thin glass planar sensors, that can be used during manufacture and through a component's life to assess parameters linked to structural performance. Hence informed decisions can be made to extend useable life and reduce the scrappage associated with manufacture. This makes most efficient use of our limited resource of energy and raw materials. In addition to environmental sustainability, this work will also have economic advantages enabling the UK economy to continue to grow innovative technology and associated highly skilled jobs. Despite the huge lightweighting benefit of composites they are not utilised to their full potential due to variability caused at the manufacturing stage. Composite components and the composite material they are made from are produced together. To achieve the desired material geometry features are included in their laminated structure that generate defects. To realise their full set of advantages new methodologies must be devised that support sustainable deployment integrated during production. At the manufacturing stage, many composite components are consigned to scrap before they go into service because of defect evolution. We are proposing a new non-invasive means to better monitor defect evolution and their affect on the final structural performance of the part. Once a composite component goes into service it is often heavier than necessary due to the design parameters necessary for safety assurance. Having an effective means of monitoring critical regions would motivate a means to reduce structural mass by reducing material usage, which in turn would allow increasing payload and or support a shift to heavier but more efficient designs. We are proposing a sensing methodology that can indicate a reduction in structural performance, as our sensors allow changes in through thickness strain to be captured. A laminated composite structure is designed to carry the load in the plane of the laminations as it is weak through the thickness of laminate. Any change in through thickness strain would be a prime indicator of a reduction in performance. At the end of the composite component's life there are currently limited options for recycling composites with 15% of the 110,000 tonnes of composites produced in the UK each year being reused at their end of life. Our sensors would support reuse and repurposing of large composite structures because a complete history of the component life cycle would be available through monitoring informing designers of the suitability to be deployed in other structural applications. To highlight the advantages of using the novel sensors we have chosen three important case studies/exemplars. The first is in the manufacture of thermosetting composites replacing the costly and time-consuming autoclave with microwave processing, which reduces energy consumption significantly. Our planar glass sensors will be non-conducting and so permit comprehensive in process monitoring, supporting uptake of microwave curing. As described above the through thickness strength of laminated composite materials is limited, hence 3D fibre architectures are being explored. Our second case study focuses on braiding process exploiting the sensor's geometry to fix it into a known position during the consolidation of the 3D fibre architecture in a thermoplastic matrix. Finally, we demonstrate the versatility of our sensors in an infield retrofitting application to extend the life of concrete infrastructure using composite repair patches.

Multi-specimen combinations of large, melt processed YBCO single grains of 25 mm diameter have been shown to trap stable magnetic fields as high as 17 T at 29 K in research-grade samples, which are simply not achievable in conventional iron-based permanent magnets (limited practically to less than ~ 1.5 T). Unfortunately, achieving and maintaining a bulk, superconducting device operating temperature of less than 65 K is difficult from a practical point of view and not particularly cost-effective. It is necessary, therefore, to develop materials with improved flux pinning (and hence field trapping) properties that can be fabricated economically for deployment in industrial applications based either on cryo-cooler technology, or on systems that use liquid nitrogen as a cryogen (boiling point, 77 K). Large single grains can be incorporated directly into existing sustainable engineering applications such as flywheels, magnetic bearings, permanent magnets for MRI/NMR, non-contact magnetic stirrers for high purity biological solutions and magnetic separators provided they can trap at least 2.0 T at 77 K. The closer the operating temperature to the transition temperature of the large single grain (typically ~ 90 K), however, the greater the requirement for effective artificial flux pinning centres in the large grain microstructure that prevent the motion of magnetic flux within the sample. The optimum size of such pinning centres is typically around a few nano-metres at 77 K. The most common method of introducing pinning centres into large YBCO grains involves engineering the size of Y2BaCuO5 (Y-211) phase inclusions in the bulk microstructure, which are produced as part of the Y-123 peritectic decomposition process during melt processing. The technique is limited fundamentally, however, by the tendency of Y-211 particles to ripen at elevated temperature, which conflicts directly with attempts to refine their size to the nano-scale. This results inevitably in a significant reduction in control of the melt process, and hence to limitations in sample performance. The PI has been involved in two important recent developments of the processing of large grain (RE)BCO superconductors. These are the development of a suitable non-211 phase that forms effective nano-scale artificial flux pinning centres, and in the development of an entirely new type of seed crystal that enables every member of the (RE)BCO class of materials to be grown in the form of large single grains by a practical techniques for the first time. The primary objective of this highly challenging project, therefore, is to fabricate mechanically stable, large, state of the art samples of single grain YBCO and other (RE)BCO melt processed superconductors than has been possible previously that contain novel (i.e. non Y-211-based), effective nano-scale artificial flux pinning centres by a practical processing technique. This will enable for the first time the cost-effective application of bulk superconductors in sustainable engineering devices that operate at, or around, 77 K. Additional objectives of this challenging proposal are to fabricate complex-shaped, new nano-phase composites for be-spoke applications for the first time using a novel multi-seeding technique, also underdevelopment at Cambridge by the PI, and to establish for the first time an effective recycling process for multi-grain samples. The project will involve extensive collaboration with four Cambridge science departments (Engineering, Materials Science, Physics and Chemistry) and with three international institutions (ATI Vienna, ICMAB Barcelona and the Boeing Company Seattle).

The SUAAVE consortium is an interdisciplinary group in the fields of computer science and engineering. Its focus is on the creation and control of swarms of helicopter UAVs (unmanned aerial vehicles) that operate autonomously (i.e not under the direct realtime control of a human), that collaborate to sense the environment, and that report their findings to a base station on the ground.Such clouds (or swarms or flocks) of helicopters have a wide variety of applications in both civil and military domains. Consider, for example, an emergency scenarion in which an individual is lost in a remote area. A cloud of cheap, autonomous, portable helicopter UAVs is rapidly deployed by search and rescue services. The UAVs are equipped with sensor devices (including heat sensitive cameras and standard video), wireless radio communication capabilities and GPS. The UAVs are tasked to search particular areas that may be distant or inaccessible and, from that point are fully autonomous - they organise themselves into the best configuration for searching, they reconfigure if UAVs are lost or damaged, they consult on the probability of a potential target being that actually sought, and they report their findings to a ground controller. At a given height, the UAVs may be out of radio range of base, and they move not only to sense the environment, but also to return interesting data to base. The same UAVs might also be used to bridge communications between ground search teams. A wide variety of other applications exist for a cloud of rapidly deployable, highly survivable UAVs, including, for example, pollution monitoring; chemical/biological/radiological weapons plume monitoring; disaster recovery - e.g. (flood) damage assessment; sniper location; communication bridging in ad hoc situations; and overflight of sensor fields for the purposes of collecting data. The novelty of these mobile sensor systems is that their movement is controlled by fully autonomous tasking algorithms with two important objectives: first, to increase sensing coverage to rapidly identify targets; and, second, to maintain network connectivity to enable real-time communication between UAVs and ground-based crews. The project has four main scientific themes: (i) wireless networking as applied in a controllable free-space transmission environment with three free directions in which UAVs can move; (ii) control theory as applied to aerial vehicles, with the intention of creating truly autonomous agents that can be tasked but do not need a man-in-the-loop control in real time to operate and communicate; (iii) artificial intelligence and optimisation theory as applied to a real search problem; (iv) data fusion from multiple, possibly heterogeneous airborne sensors as applied to construct and present accurate information to situation commanders. The SUAAVE project will adopt a practical engineering approach, building real prototypes in conjunction with an impressive list of external partners, including a government agency, the field's industry leaders, and two international collaborators.