BAE Systems with the support of EPSRC have launched a challenge to universities to develop novel technologies that can be applied to new and aspirational aircraft programmes. In particular, the Persistent Green Air Vehicle (PERGAVE) concept is a future unmanned air vehicle (UAV), not yet an aircraft design, which can sustain missions of at least months' and ultimately more than a year's duration. In this respect, PERGAVE is a highly flexible HALE (High Altitude Long Endurance) aircraft, with vibration and aeroelastic characteristics specific to each PERGAVE design concept. Methodologies have been developed by NASA to predict flight dynamics of HALE aircraft. An operational profile such as this will require extremely low energy demands from on-board systems to meet both the endurance and environmental targets. It will also require comprehensive condition monitoring of structures and systems (e.g. vibration and loading) as well as environmental parameter measurement (e.g. temperature, ionizing radiation levels and doses) to allow operators to assess the viability of the aircraft at every stage of its mission. This project will respond to the PERGAVE challenge by developing energy harvesting powered wireless data links and real time condition and environmental sensor nodes in an integrated smart composite airframe structure for monitoring. The nodes will operate in an energy autonomous manner, without the need for power supplies or batteries and therefore it is truly energy autonomous. The research has the following five work packages: WP1: Requirement capture and study of the system design specifications and architecture WP2: Integration of the energy harvesting element into the composite structure WP3: Multiphysical modelling and simulation for optimisation of the whole system WP4: Development of low power consumption wireless sensor nodes WP5: Testing of the technology demonstrator The WPs will specifically target design and demonstration of a deployable real time energy autonomous wireless sensing communication systems that can be used for structural health monitoring and environmental parameter measurement aligned to the next generation, unmanned air vehicle programme in BAE Systems. Uniquely in the UK, this work will take a system level specification and design approach combining optimisation with novel energy harvesting technology designed for flexible deployment in manufactured composite structures with wireless sensing, which are all integrated in a novel energy and power management architecture. This provides end-to-end capability that will be suitable not only for the PERGAVE vehicle but also for other applications requiring remote asset condition monitoring in harsh environments (e.g. off-shore wind farms). The principal novelty of the project lies in the implementation of combined materials and structures design, optimisation and manufacturing processes, our enhanced energy harvesting technology and efficient energy-aware and energy-flow control mechanism, which has the potential to be prototyped as a self-powered, light weight and wireless health monitoring system for future air vehicles. The research will build on investigator track records on energy harvesting with wireless sensing, sensors and aerospace monitoring, and composite manufacturing at Cranfield University, aircraft and composite structural modelling and optimization at Lancaster University, and ionizing radiation monitoring at the University of Central Lancashire to undertake this timing and challenging project. The project partners are BAE Systems in Military Air&Information and Advanced Technology Centre, AgustaWestland Ltd, TRW, dstl, EPSRC National Centres for Innovative Manufacturing in Through-life Engineering Services. These partners represents aerospace, defence and automotive sectors. There are Aerospace, Aviation & Defence KTN and Zartech organisations as dissemination partners to support the impact activities.

Adaptive Aerostructures for Power and Transportation Sustainability (AdAPTS) is an Early Career Fellowship research project which will advance an ambitious new approach to the design of aerostructures by harnessing the adaptability of compliance-based morphing to continuously optimise aerodynamic performance. This will allow for greener and more sustainable fixed and rotary wing transportation and wind turbine power generation through reduced aerodynamic drag, increased efficiency and improved resilience to changing operating conditions. Compliance-based adaptive aerostructures are designed to exhibit structural and material flexibility that allows them to change their shape in a smooth and continuous manner. These changes in shape are isolated to certain desired motions in specific areas of an aerodynamic surface, for example the amount of curvature at the rear of an aerofoil, to allow for targeted changes in shape while retaining overall strength. These changes in shape improve the ability of the wing or blade to produce lift, minimise the amount of drag generated, and allow for continuous adaptation to changing operating conditions. Initial work has shown that the family of compliance-based morphing devices developed by the PI can provide significant improvements in performance of 5-25%. While the potential benefits are promising, much work remains to make compliance-based morphing a viable solution. These types of structures are poorly understood, and the underlying technologies need significant development. The poor understanding of the performance and behaviour of these structures is due to their compliant nature, which means that the structural, aerodynamic, and actuation characteristics are all highly coupled - with the aerodynamic loading affecting the actuated shape, which in turn affects the aerodynamics. This coupling requires simulation of all of the physics involved in a cohesive, coupled manner. Furthermore, the structural, material, and actuation technologies used to achieve these smooth and continuous deformed shapes are novel, and therefore significant effort is needed to mature them to the point where they can be used in real-world applications. Finally, industry partners in the fixed wing, rotary wing, and wind turbine fields see the potential in these technologies, but because they are so novel and different from current approaches, work needs to be done to show the specific, quantitative improvements in performance that these technologies can achieve for their applications. To address the three sides of this problem, AdAPTS will undertake an ambitious research programme with three parallel streams of work that will: 1.) create a fully comprehensive analysis framework to better understand the hierarchical, coupled performance of compliance-based morphing structures from the bottom up, 2.) rapidly mature the proposed morphing technologies, and 3.) work directly with industry to analyse and design adaptive structures for their products, and to predict the achievable improvements in performance.

As the relevant technologies develop, energy efficient electric power systems are replacing equivalent hydraulic, pneumatic and mechanical systems. This is most apparent in the transportation sector in which energy efficiency is of primary importance, leading to increased range and reduced vehicle emissions and fuel consumption, essential if the UK is to meet EC emissions targets by 2020. Working towards these targets, the current generation of electric technologies are already providing the back-up and auxiliary systems on the newest civil aircraft and motive power on the very latest hybrid and electric vehicles. Looking to the future, the next generation of civil airliners are expected to use electric power as the primary source (except for propulsion) meaning that they will have an on-board electrical generation capacity of around 1MW. Efficient generation, distribution and consumption of this amount of energy in the face of continuously changing power demands of an aircraft during flight requires complex power conversion systems which add mass to the aircraft, reducing the overall system benefits. This has more impact on smaller aircraft such as helicopters as the mass of the extra equipment needed forms a greater proportion of the total vehicle mass. To truly viable in smaller aircraft, the power conversion systems must be lighter, occupy less space and still be capable of delivering the required power safely, operating much closer to the limit of their capabilities.Broadly, this research programme proposes in will investigate two concepts;1. A low mass power conversion system that could be used to drive electric systems in which require a supply frequency that is at a fixed ratio to that of the primary generation system is proposed and analysed in terms of its stability. The resulting converter would be extremely efficient and would increase the likelihood that large electric power technologies (e.g. for propulsion) could be used on helicopters safely.2. A testing method that will allow the critical pieces of equipment (be they software or hardware) to be dynamically loaded and tested in the lab as if they were present in the complete, real system for which they were designed.Specifically the research will take the form of an in-depth analytical study that will determine theoretically and demonstrate experimentally using real-time dynamic substructuring methods, the dynamic stability and control of the proposed power conversion topology. As the topology does not require an intermediate fully rated power electronics stage, it has many benefits including low mass, very high efficiency and little electro-magnetic interference (EMI) which also means heavy EMI filters will not be required.For validation and a reliable assessment of the true stability of the system under loading, a phase of laboratory-based testing will be conducted that will use and assess state-of-the-art control, real-time numerical modelling coupled with load and source emulation techniques (which combine to form a real-time dynamic substructured test) to accurately reproduce the controlled output of a field-wound aircraft generator, and the fan loading of a propeller, with a view to replicating the dynamic conditions observed under true operating conditions.Finally a phase of full laboratory tests will be conduction to demonstrate the accuracy and validity of the implementation of the real-time dynamically substructured test facility.

The aim of this proposal is to transform the design and manufacture of structural systems by relieving the bottleneck caused by the current practice of restricting designs to a linear dynamic regime. Our ambition is to not only address the challenge of dealing with nonlinearity, but to unlock the huge potential which can be gained from exploiting its positive attributes. The outputs will be a suite of novel modelling and control techniques which can be used directly in the design processes for structural systems, which we will demonstrate on a series of industry based experimental demonstrators. These design tools will enable a transformation in the performance of engineering structural systems which are under rapidly increasing demands from technological, economic and environmental pressures. The performance of engineering structures and systems is governed by how well they behave in their operating environment. For a significant number of engineering sectors, such as wind power generation, automotive, medical robotics, aerospace and large civil infrastructure, dynamic effects dominate the operational regime. As a result, understanding structural dynamics is crucial for ensuring that we have safe, reliable and efficient structures. In fact, the related mathematical problems extend to other modelling problems encountered in other important research areas such as systems biology, physiological modelling and information technology. So what exactly is the problem we are seeking to address in this proposal? Typically, when the behaviour of an engineering system is linear, computer simulations can be used to make very accurate predictions of its dynamic behaviour. The concept of end-to-end simulation and virtual prototyping, verification and testing has become a key paradigm across many sectors. The problem with this simulation based approach is that it is built on implicit assumptions of repeatability and linearity. For example, many structural analysis methods are based on the concept of a frequency domain charaterisation, which assumes that response of the system can be characterised by linear superposition of the response to each frequency seperately. But, the response of nonlinear systems is known to display amplitude dependence, sensitivity to transient effects in the forcing, and potential bistability or multiplicity of outcome for the same input frequency. As a result, when the system is nonlinear (which is nearly always the case for a large number of important industrial problems) it is almost impossible to make dynamic predictions without introducing very limiting approximations and simplifications. For example, throughout recent history, there have been many examples of unwanted vibrations; Failure of the Tacoma Narrows bridge (1940); cable-deck coupled vibrations on the DongTing Lake Bridge (1999); human induced vibration on the Millennium Bridge (2000); NASA Helios failure (2003); Coupling between thrusters and natural frequencies of the flexible structure on the International Space Station (2009); Landing gear shimmy. In many cases, the complexity of modern designs has outstripped our ability to understand their dynamic behaviour in detail. Even with the benefit of high power computing, which has enabled engineers to carry out detailed simulations, interpreting results from these simulations is a fundamental bottleneck, and it would seem that our ability to match experimental results is not improving, due primarily to the combination of random and uncertain effects and the failure of the linear superposition approach. As a result a new type of structural dynamics, which fully embraces nonlinearity, is urgently needed to enable the most efficient design and manufacture of the next generation of engineering structures.

The aim of this proposal is to transform the design and manufacture of structural systems by relieving the bottleneck caused by the current practice of restricting designs to a linear dynamic regime. Our ambition is to not only address the challenge of dealing with nonlinearity, but to unlock the huge potential which can be gained from exploiting its positive attributes. The outputs will be a suite of novel modelling and control techniques which can be used directly in the design processes for structural systems, which we will demonstrate on a series of industry based experimental demonstrators. These design tools will enable a transformation in the performance of engineering structural systems which are under rapidly increasing demands from technological, economic and environmental pressures. The performance of engineering structures and systems is governed by how well they behave in their operating environment. For a significant number of engineering sectors, such as wind power generation, automotive, medical robotics, aerospace and large civil infrastructure, dynamic effects dominate the operational regime. As a result, understanding structural dynamics is crucial for ensuring that we have safe, reliable and efficient structures. In fact, the related mathematical problems extend to other modelling problems encountered in other important research areas such as systems biology, physiological modelling and information technology. So what exactly is the problem we are seeking to address in this proposal? Typically, when the behaviour of an engineering system is linear, computer simulations can be used to make very accurate predictions of its dynamic behaviour. The concept of end-to-end simulation and virtual prototyping, verification and testing has become a key paradigm across many sectors. The problem with this simulation based approach is that it is built on implicit assumptions of repeatability and linearity. For example, many structural analysis methods are based on the concept of a frequency domain charaterisation, which assumes that response of the system can be characterised by linear superposition of the response to each frequency seperately. But, the response of nonlinear systems is known to display amplitude dependence, sensitivity to transient effects in the forcing, and potential bistability or multiplicity of outcome for the same input frequency. As a result, when the system is nonlinear (which is nearly always the case for a large number of important industrial problems) it is almost impossible to make dynamic predictions without introducing very limiting approximations and simplifications. For example, throughout recent history, there have been many examples of unwanted vibrations; Failure of the Tacoma Narrows bridge (1940); cable-deck coupled vibrations on the DongTing Lake Bridge (1999); human induced vibration on the Millennium Bridge (2000); NASA Helios failure (2003); Coupling between thrusters and natural frequencies of the flexible structure on the International Space Station (2009); Landing gear shimmy. In many cases, the complexity of modern designs has outstripped our ability to understand their dynamic behaviour in detail. Even with the benefit of high power computing, which has enabled engineers to carry out detailed simulations, interpreting results from these simulations is a fundamental bottleneck, and it would seem that our ability to match experimental results is not improving, due primarily to the combination of random and uncertain effects and the failure of the linear superposition approach. As a result a new type of structural dynamics, which fully embraces nonlinearity, is urgently needed to enable the most efficient design and manufacture of the next generation of engineering structures.