PhD and MSc by research theses (SATM)
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Item Open Access Active magnetic bearing for ultra precision flexible electronics production system(Cranfield University, 2015-12) Tantau, Mathias; Shore, Paul; Morantz, PaulRoll-to-roll printing on continuous plastic films could enable the production of flexible electronics at high speed and low cost, but the granularity of feature sizes is limited by the system accuracy. Technologies such as gravure printing and nanoimprint lithography demand a level of rotary motion precision that cannot be achieved with rolling element bearings. Manufacturing tolerances of the rotating parts, thermal drift and process forces in combination with structural compliance add up to additional error motions. In this master by research an active magnetic bearing (AMB) solution is designed for a new, super-sized roll-to-roll flexible electronics production machine, which was so far based on hydrostatic bearings. The magnetic bearing could actively compensate the accumulated synchronous error and maintain high accuracy under all conditions. However, the asynchronous error of a conventional AMB with the required size and power is a problem. In order to reduce the relatively high positioning uncertainty of active magnetic bearings an innovative radial position measurement based on linear, incremental encoders with optical conversion principle is proposed. A commercial encoder scanning head faces a round scale with concentric, coplanar lines on its face. By counting these lines the radial position can be measured. Because such a scale is not readily available, it is made by micro-machining. In experiments, different machining methods are compared. Then a magnetic bearing is built to demonstrate the efficacy of the proposed sensor. As a result, the best measurement noise is 3.5nm at 10kHz and a position uncertainty of approximately 0.25µm has been achieved for the magnetic bearing. These promising results are especially interesting for applications with high precision requirements at low speed of rotation.Item Open Access Adhesive joint geometry variation in non-rigid aircraft structures(Cranfield University, 2019-11) Coladas Mato, Pablo; Webb, Phil; Xu, YigengAdhesive bonding is a proven alternative to mechanical fasteners for structural assembly, offering lighter and thus more fuel efficient aircraft and cost-effective manufacturing processes. The effective application of bonded structural assemblies is however limited by the tight fit-up requirement, which is with tolerance ranges of hundreds of microns; this can be a challenge for the industry to meet considering the variability of current part manufacturing methods and the conservative nature of the conventional tolerance stack-up analysis method. Such a (perceived) limitation can discourage effective exploitation of bonding technologies, or lead to development of overengineered solutions for assurance. This work addresses such challenge by presenting an enhanced bondline thickness variation analysis accounting for part deflection of a bonded skinstringer assembly representing a typical non-rigid airframe structure. A semianalytical model accounting for unilateral contact and simplified 1D adhesive flow has been developed to predict bondline thickness variation of the assembly given the adherends’ mechanical properties, adhesive rheological properties, and external assembly forces or boundary conditions. A spectral-analysis method for assembly force requirement estimation has also been tested. The bondline dimensions of several representative test articles have been interrogated, including a reconfigurable test assembly designed specifically to test the input conditions that affect bondline geometry variation. It has been demonstrated that the part deflections need to be accounted for regarding the fit-up requirement of bonded non-rigid structural assembly. The semi-analytical model has been found to more reliable and realistic prediction of bondline thickness when compared to a rigid tolerance stack-up. The analysis method presented can be a major technology enabler for faster, more economical development of the aircraft of the future, as well as of any analogue structures with high aspect ratios where weight savings and fatigue performance may be core objectives.Item Open Access Adoption of product service systems in health care.(2017-10) Mittermeyer, Stephan Alexander; Tomiyama, Tetsuo; Tiwari, AshutoshHealth care systems are constantly challenged to deliver better quality of care at lower cost. Product Services Systems (PSS) aim to output a higher value to a customer, while reducing resource input required to achieve such value and sustainability. In the health care market this could help companies increase their focus on value for the patient, but also for the health care system as such. This focus on value can ultimately help drive down health care cost, which is one of the most pressing issues in health care systems today. The potential of PSS to address some of the major challenges in the health care market was recognised early in PSS research, however adoption in this field is still below expectation. Motivated by the potential of PSS in health care this work aims to explore the current status of adoption as well as drivers and barriers to future adoption in this market and evaluates if and how PSS can be designed and implemented by companies active in this market. This work showed that PSS can be feasible and useful in this sector as they address relevant current challenges. Future changes in the health care market will likely make PSS even more relevant. Certain concepts of PSS are already applied in the market without leveraging the benefits of a fully developed PSS. Limitations in how the value for patients and other market actors is determined and made transparent is a major challenge in the adoption of PSS. An assessment method is proposed to enable companies to evaluate the value generation of their PSS offerings. In addition, a guideline for PSS design is proposed based on results of this work and field observations. This thesis contributes to a better understanding of PSS adoption in health care by investigating mechanisms in the health care market to understand if PSS can be implemented in a useful manner and how PSS can be adopted in health care in the future. As PSS consists of a number of separate concepts that may be used by themselves and also outside a PSS concept, a detailed analysis was performed to evaluate how PSS concepts are already utilized by industry, as such partial implementations may be a good starting point for full PSS adoption. Adoption of a PSS in any industry requires a measure to evaluate the success of a system implementation or the quality of PSS offerings. Given the complex market network in health care, metrics for evaluations have been identified, linking different dimensions of clinical utility to PSS. Those metrics enable companies to assess PSS systems or scenarios, but also enable development teams to focus their PSS design efforts, as those assessment metrics provide a framework for PSS requirements engineering in this market. Based on the results of the work outlined above, design guidelines were defined to support the development process of PSS in health care.Item Open Access Advanced carbon/flax/epoxy composite material for vehicle applications: vibration testing, finite elements modelling, mechanical and damping characterization.(Cranfield University, 2015-05) Ampatzidis, Theofanis; Blackburn, Kim; Abhyankar, HrushikeshNowadays, research in automotive and construction industries focuses on materials that offer low density along with superior dynamic and static performance. This goal has led to increasing use of composites in general, and carbon fibre (CF) composites in particular. CF composites have been adopted widely in the space industry and motorsports. However, their high stiffness and low density leads to low damping performance, which is responsible for increased levels of noise and reduction in service life. On the other hand, natural fibres (NF) like flax fibres (FF) are capable of delivering a much better damping performance. A hybrid composite comprising of FF and CF can potentially deliver both on strength and higher damping performance. In this study the mechanical and damping properties of CF, FF and their hybrid composites were examined. Composites' anisotropic nature affects their response to vibrations and so traditional damping experimental setups used for metals had to be ruled out. A damping set up based on Centre Impedance Method (CIM) was adopted for the purpose of this study which was based on an ISO standard originally developed for glass laminates. Standard tensile and flexural tests were conducted in order to characterise the performance of the hybrid composite. The experimental work was accompanied by finite elements analysis (FEA). The experimental data and FEA were used to optimize the hybrid structure layup with respect to damping and structural response.Item Open Access Advanced flow technologies for the controlled & continuous manufacture of nanoscale materials(Cranfield University, 2019) Isaev, Svetlin; Makatsoris, Charalampos (Harris)Batch processes have been successfully used in the process industry over two centuries. However, changing customer demands and discovery of novel products have led the scientists and engineers to develop new manufacturing methods for the process industry. High-value products such as nanomaterials, smart and functional materials require precise process control for the entire product. Controlling of particle size and shape becomes more difficult in the large scale batch processes. Therefore, over the past few decades, there has been an increasing interest in the flow processing techniques due to their inherent benefits, such as better heat and mass transfer and small control volumes. Continuous Oscillatory Baffled Reactor (COBR) is a novel type of flow reactor. COBR combines oscillatory motion and periodically placed baffled flow channels to generate plug flow conditions, providing better mixing control similar to microreactors. Plug flow conditions can be achieved with the combination of optimum net flow, oscillatory amplitude and frequency using COBRs. With this new reactor and mixing concept, high-value products can be manufactured more efficiently using uniform mixing conditions and better temperature control. This will decrease the reaction time and production cost of novel products, use less energy, and increase time-to-market of novel products. The aim of this research is to develop a scalable and continuous manufacturing platform using continuous oscillatory baffled reactors to produce high-value products in low cost. The focus of this study includes developing modular oscillatory baffled reactors, characterisation of modular oscillatory baffled reactors using experimental methods, developing scale-up methodology from laboratory scale to industrial production size and demonstration of nanomaterial synthesis using modular oscillatory flow reactor...[cont.]Item Open Access Advanced numerical methods for dissipative and non-dissipative relativistic hydrodynamics(Cranfield University, 2020-05) Townsend, Jamie F.; Konozsy, Laszlo Z.; Jenkins, Karl W.High-energy physical phenomena such as astrophysical events and heavy-ion collisions contain a hydrodynamic aspect in which a branch of fluid dynamics called relativistic hydrodynamics (RHD) is required for its mathematical description. The resulting equations must be, more often than not, solved numerically for scientists to ascertain useful information regarding the fluid system in question. This thesis describes and presents a twodimensional computational fluid dynamics (CFD) solver for dissipative and non-dissipative relativistic hydrodynamics, i.e. in the presence and absence of physically resolved viscosity and heat conduction. The solver is based on a finite volume, Godunov-type, HighResolution Shock-Capturing (HRSC) framework, containing a plethora of numerical implementations such as high-order Weighted-Essentially Non-Oscillatory (WENO) spatial reconstruction, approximate Riemann solvers and a third-order Total Variation Diminishing (TVD) Runge–Kutta method. The base numerical solver for the solution of non-dissipative RHD is extensively tested using a series of one-dimensional test cases, namely, a smooth flow problem and shock-tube configurations as well as the two-dimensional vortex sheet and Riemann problem test cases. For the case of non-dissipative relativistic hydrodynamics the relativistic CFD solver is found to perform well in terms of the orders of accuracy achieved and its ability to resolve shock wave patterns. Numerical pathologies have been identified when the relativistic HLLC Riemann solver is used in multi-dimensions for problems exhibiting strong shock waves. This is attributed to the so-called Carbuncle problem which is shown to occur because of pressure differencing within the process of restoring the missing contact discontinuity of its predecessor, the HLL Riemann solver. To avoid this numerical pathology and improve the robustness of numerical solutions that make use of the HLLC Riemann solver, the development of a rotated-hybrid Riemann solver arising from the hybridisation of the HLL and HLLC (or Rusanov and HLLC) approximate Riemann solvers is presented. A standalone application of the HLLC Riemann solver can produce spurious numerical artefacts when it is employed in conjunction with Godunov-type high-order methods in the presence of discontinuities. It has been found that a rotated-hybrid Riemann solver with the proposed HLL/HLLC (Rusanov/HLLC) scheme could overcome the difficulty of the spurious numerical artefacts and presents a robust solution for the Carbuncle problem. The proposed rotated-hybrid Riemann solver provides sufficient numerical dissipation to capture the behaviour of strong shock waves for relativistic hydrodynamics. Therefore, focus is placed on two benchmark test cases (odd-even decoupling and double-Mach reflection problems) and the investigation of two astrophysical phenomena, the relativistic Richtmyer– Meshkov instability and the propagation of a relativistic jet. In all presented test cases, the Carbuncle problem is shown to be eliminated by employing the proposed rotated-hybrid Riemann solver. This strategy is problem-independent, straightforward to implement and provides a consistent robust numerical solution when combined with Godunov-type highorder schemes for relativistic hydrodynamics...[cont.]Item Open Access Advanced uncertainty quantification with dynamic prediction techniques under limited data for industrial maintenance applications.(Cranfield University, 2021-07) Grenyer, Alex; Erkoyuncu, John Ahmet; Zhao, YifanEngineering systems are expected to function effectively whilst maintaining reliability in service. These systems consist of various equipment units, many of which are maintained on a corrective or time-based basis. Challenges to plan maintenance accounting for turnaround times, equipment availability and resulting costs manifest varying degrees of uncertainty stemming from multiple quantitative and qualitative (compound) sources throughout the in-service life. Under or over-estimating this uncertainty can lead to increased failure rates or, more often, unnecessary maintenance being carried out. As well as the quality availability of data, uncertainty is driven by the influence of expert experience or assumptions and environmental operating conditions. Accommodating for uncertainty requires the determination of key contributors, their influence on interconnected units and how this might change over time. This research aims to develop a modelling approach to quantify, aggregate and forecast uncertainty given by a combination of historic equipment data and heuristic estimates for in-service engineering systems. Research gaps and challenges are identified through a systematic literature review and supported by a series of surveys and interviews with industrial practitioners. These are addressed by the development of two frameworks: (1) quantify and aggregate compound uncertainty, and (2) predict uncertainty under limited data. The two frameworks are brought together to produce the Multistep Compound Dynamic Uncertainty Quantification (MCDUQ) app, developed in MATLAB. Results demonstrate effective measurement of compound uncertainties and their impact on system reliability, along with robust predictions under limited data with an immersive visualisation of dynamic uncertainty. The embedded frameworks are each validated through implementation in two case studies. The app is verified with industrial experts through a series of interviews and virtual demonstrations.Item Open Access Aeroacoustic simulation of rotorcraft propulsion systems.(Cranfield University, 2019-11) Vouros, Stavros; Pachidis, VassiliosRotorcraft constitute air vehicles with unique capabilities, including vertical take- off and landing, hover and forward/backward/lateral flight. The efficiency of rotorcraft operations is expected to improve rapidly, due to the incorporation of novel technologies into current designs. Moreover, enhanced or even new capabilities are anticipated after the introduction of advanced fast rotorcraft configurations into the future fleet. The forecast growth in rotorcraft operations is essentially associated with an expected increase in adverse environmental impact. With respect to the forthcoming rotorcraft aviation advancements, regulatory and advisory bodies, as well as communities, have focused their attention on reducing pollutant emissions and acoustic impact of rotorcraft activity. Consequently, robust and computationally efficient noise modelling approaches are deemed as prerequisites towards quantifying the acoustic impact of present and future rotorcraft activity. Ultimately, these approaches need to cater for unique operational conditions encompassed by modern rotorcraft across designated flight procedures. Additionally, individual variations of key design variables need to be resolved, in the context of design or operational optimisation, targeted at noise mitigation. This work elaborates on the development and application of a robust and computationally efficient methodology for the aeroacoustic simulation of rotorcraft propulsion systems. A series of fundamental modelling methods is developed for the prediction of helicopter rotor noise at fully-integrated operational level. An extensive validation is carried out against existing experimental data with respect to prediction of challenging aeroacoustic phenomena arising from complex aerodynamic interactions. The robustness of the deployed method is confirmed through a cost-effective uncertainty analysis method focused on aerodynamic sources of uncertainty. A set of generalised modelling guidelines is devised for the case of not available input parameters to calibrate the aerodynamic models. The aspect of multi-disciplinary optimisation of rotorcraft at aircraft level in terms of maximising the potential benefits of novel technologies is also tackled within this work. A holistic schedule of optimal active rotor morphing control is derived, offering simultaneous mitigation of pollutant emissions and acoustic impact across a wide range of the helicopter flight envelope. Finally, the developed noise prediction method is incorporated into an operational-level optimisation algorithm, demonstrating the potential of active rotor morphing with respect to reduction of ground-noise impact. The contribution to knowledge arising from the successful completion of this work comprises both the development of methodologies for helicopter aeroacoustic analysis and the derivation of guidelines and best practices for morphing rotor control. Specifically, a generic operational-level simulation approach is developed which effectively advances the state-of-the-art in mission noise prediction. New insight is provided with respect to the impact of wake aerodynamic modelling uncertainty on the robustness of noise predictions. Moreover, the aeroacoustic aspects of a novel morphing rotor concept are explored and quantifications with respect to the trade-off between environmental and noise disciplines are offered. Finally, a generalised set of optimal rotor control guidelines is derived towards achieving the challenging environmental goals set for a sustainable future rotorcraft aviation.Item Open Access Aerodynamic analysis and experiment of a micro flapping wing rotor(Cranfield University, 2015-03) Li, Hao; Guo, Shijun J.This project is aimed at developing a bio-inspired flyable micro/nano aerial vehicle (MAV) of high agility and performance capable of vertical take-off and landing and hovering (VTOLH). To achieve the aim, a novel flapping wing rotor (FWR) concept invented by Dr. Guo has been adopted, which is ideal for MAVs of sub 60 gm and especially for nano scale of sub 5 gm according to aerospace industry’s definition. The advantages and potential of the FWR concept for MAV development has been studied consistently by Dr. Guo’s research team in the last five years. However making a flyable micro FWR model especially in sub 5gm and demonstrate its VTOLH feasibility remains as a big challenge and has not been achieved in previous projects. To meet the above objective, the first achievement in the project is the successful design, build and test of a flyable micro FWR model (FWR-EX1) of only 3 gm based on off-the-shelf available micro motor. The key breakthrough is to achieve the necessary large aeroelastic twist of the flapping wing during the upstroke in an adaptive manner for structural and aerodynamic efficiency. To achieve the next objective for design and performance improvement, study has also been focused on deeper scientific understanding and analysis of the FWR mechanisms. Attention has therefore been paid to a systematic study on aerodynamic modelling and efficiency of the FWR. The method is based on a revised quasi-steady aerodynamic model that combines the theoretical method and experimental data. The numerical results of the revised quasi-steady aerodynamic model are in agreement with existing results obtained via CFD methods. Based on the model and analysis, the optimal kinematics for the FWR has been determined. Subsequently a comparison of the FWR aerodynamic efficiency was made with two other most studied configurations of MAVs, the insect flapping wing and rotorcraft ... [cont.].Item Open Access Aerodynamic analysis of large wind farms using two-scale coupled modelling approaches.(2021-08) Ma, Lun; Tsoutsanis, Panagiotis; Antoniadis, AntoniosThe effects of turbine aerodynamics and response characteristics of the atmospheric boundary layer on the overall wind farm efficiency are investigated in this research. Various wind farm modelling strategies, which include a theoretical and several CFD models, are presented. This study consists of three main parts: (i) improve and validate an existing theoretical wind farm model, (ii) infinitely large wind farm modelling with actuator-disc and fully-resolved turbine models, and (iii) finite-size wind farm modelling with a numerical weather prediction model. In the first part, an extended theoretical model based on a two-scale coupled momentum balance method is proposed to estimate aerodynamic effects of wind turbine towers on the performance of large wind farms. The modified theoretical model predicts that the optimal turbine spacing should increase with the value of normalised support-structure drag, as well as additional parameters describing the response characteristics of the atmospheric boundary layer to the total farm drag. The Detached-Eddy simulations of a periodic array of fully staggered actuator discs (AD) show a reasonably good agreement (within 10% in the prediction of power) with the modified theoretical model. In the second part, a fully resolved (FR) NREL 5MW turbine model is employed in two URANS simulations (with and without the turbine tower) of a fully developed wind farm boundary layer. The FR-URANS results show stronger tower effects than both AD-RANS and theoretical model predictions, which is a strong indication of the necessity of considering turbine support structure within large wind farm models. The possibility of performing DDES is also investigated with the same FR turbine model and periodic domain setup. The results show complex turbulent flow characteristics within a large wind farm, where typical hairpin and hub vortices have been clearly captured. In addition, the computational cost of DDES has been found to be similar to URANS (for a given number of rotations), which is a positive sign for conducting DDES in future studies. In the third part, a numerical weather prediction model is used as a realistic farm-scale flow model to investigate how the streamwise pressure gradient, Coriolis force and acceleration/deceleration terms in the farm-scale momentum balance equation tend to change in time. The results suggest that the streamwise pressure gradient may be enhanced substantially by the resistance caused by the wind farm, whereas its influence on the other two terms appears to be relatively minor. These results suggest the importance of modelling the farm-induced pressure gradient accurately for various weather conditions in future studies of large wind farmsItem Open Access Aerodynamic and cost modelling for aircraft in a multi-disciplinary design context.(Cranfield University, 2015-12) Di Pasquale, Davide; Savill, Mark A.; Kipouros, Timoleon; Holden, CarrenA challenge for the scientific community is to adapt to and exploit the trend towards greater multidisciplinary focus in research and technology. This work is concerned with multi-disciplinary design for whole aircraft configuration, including aero performance and financial considerations jointly for an aircraft program. A Multi-Disciplinary (MD) approach is required to increase the robustness of the preliminary design data and to realise the overall aircraft performance objectives within the required timescales. A pre-requisite for such an approach is the existence of efficient and fully integrated processes. For this purpose an automatic aero high-speed analysis framework has been developed and integrated using a commercial integration/building environment. Starting from the geometry input, it automatically generates aero data for loads in a timescale consistent with level requirement, which can afterwards be integrated into the overall multi-disciplinary process. A 3D Aero-solution chain has been implemented as a high-speed aerodynamic evaluation capability, and although there is not yet a complementary fully automated Aerodynamic design process, two integrated systems to perform multi-objective optimisation have been developed using different optimisation approaches. In addition to achieving good aircraft performance, reducing cost may be essential for manufacturer survival in today's competitive market. There is thus a strong need to understand the cost associated with different competing concepts and this could be addressed by incorporating cost estimation in the design process along with other analyses to achieve economic and efficient aircraft. For this reason a pre-existing cost model has been examined, tested, improved, and new features added. Afterwards, the cost suite has been integrated using an integration framework and automatically linked with external domains, providing a capability to take input from other domain tool sets. In this way the cost model could be implemented in a multi-disciplinary process allowing a trade-off between weight, aero performance and cost. Additionally, studies have been performed that link aerodynamic characteristics with cost figures and reinforce the importance of considering aerodynamic, structural and cost disciplines simultaneously. The proposed work therefore offers a strong basis for further development. The modularity of the aero optimisation framework already allows the application of such techniques to real engineering test cases, and, in future, could be combined with the 3D aero solution chain developed. In order to further reduce design wall-clock time the present multi- level parallelisation could also be deployed within a more rapid multi-fidelity approach. Finally the 3D aero-solution chain could be improved by directly incorporating a module to generate aero data for performance, and linking this to the cost suite informed by the same geometrical variables.Item Open Access The aerodynamics of aero-engine Nacalles.(2018-02) Robinson, Matthew H.; MacManus, David G.This thesis deals with the aerodynamics of aero-engine nacelles with a focus on the influence of a short and slim nacelle design on the drag performance. As turbofan engines are designed with increasingly reduced specific thrusts in order to improve propulsive efficiency, the fan diameter tends to grow. With a larger fan, the engine weight and nacelle drag grow which may offset the benefit from the reduced specific thrust. It is imperative to determine if a reduced length and thickness nacelle, compared to a conventional design, will enable the viable use of these reduced specific thrust aero-engine designs. The research aims to answer this question with a focus on cruise drag, spillage drag, drag rise and windmill performance of isolated and installed short, and slim nacelles. An innovative optimisation process was developed with a computational fluid dynamics process included as a means to evaluate nacelle drag. This was applied to different nacelle designs in a novel design space to optimise for cruise and off-design performance with a multi-objective genetic algorithm. The optimisation routine was extensively tested and verified against a number of analytical functions to ensure it could adequately approximate optimal Pareto sets. The optimisation of both axisymmetric and non-axisymmetric nacelles was carried out on drag, spillage and drag rise Mach number as well as on two metrics which control the pressure distribution of the nacelle. Optimal nacelles were then chosen to study the influence of nacelle incidence, the windmill condition and installation onto an aircraft on the drag performance and to provide a new quantification of these impacts. The optimisation demonstrated that under cruise conditions it is possible to have compact nacelle designs that offer reductions in drag. For example, a nacelle with a 23% reduction in length resulted in a 22% reduction in nacelle drag. However, these compact designs are more sensitive to off design condition. Specifically the spillage drag at a required drag rise Mach number of 0.87 could be 9 times higher for the reduced length nacelle. Nonetheless, it is possible to create a nacelle at the shortest length tested which had spillage of less than 6% of the cruise drag and met all requirements on drag rise to cruise at a Mach number of 0.85. This was enabled by an increase in the trailing edge radius such that it was equal to the highlight radius which improved the wave drag characteristics. Whilst the shortened nacelle was viable at low incidence, the increased wave drag resulted in the drag benefit relative to the conventional design being negated by an incidence of 6 degrees. In addition, this reduced length nacelle experienced separation at the end of runway windmill condition at 22 degrees, which is below the requirement of 30 degrees. Once installed on an aircraft the impact of reducing the nacelle length was a decrease in overall cruise aircraft drag of 3%. These studies demonstrate that there is a significant cruise benefit available from a short nacelle but that the off design conditions, most notably windmill requirements, will need to be addressed.Item Open Access Aeroelastic analysis on a multi-element composite wing in ground effect using fluid-structure interaction.(Cranfield University, 2021-08) Bang, Chris Sungkyun; Temple, Chris; Konozsy, Laszlo Z.The present research focuses on an advanced coupling of computational fluid dynamics (CFD) and structural analysis (FEA) on the aeroelastic behaviour of a multi-element inverted composite wing with the novelty of including the ground effect. Due to the elastic properties of composite materials, Formula One (F1) car’s front wing may become flexible under fluid loading, modifying the flow field and eventually affecting overall aerodynamics. This research investigates the influence of elastic behaviour of the wing in ground proximity on the aerodynamic and structural performance by setting up an accurate the Fluid-Structure Interaction (FSI) modelling framework. A steady-state two-way coupling method is exploited to run the FSI simulations using ANSYS, which enables simultaneous calculation by coupling CFD with FEA. A grid sensitivity study and turbulence model study are preferentially performed to enhance confidence of the numerical approach. The FSI study encompasses everything from basic examination and measurement of the interaction phenomena using a single and double element inverted wing to the creation of a multi-objective wing design optimisation procedure. The computational results obtained from FSI simulations are assessed and compared with the experimentation with respect to surface pressure distribution, aerodynamic associated forces, and wake profiles. Concerning structure layups, ply orientation and core materials, the effect of various composite structure configurations on the wing performance is extensively studied. An efficient and unique decomposition-based optimisation framework utilising the response surface model is provided based on the aero-structural coupled analysis in order to enhance the wing design process' accuracy and efficiency while tackling aeroelastic phenomena.Item Open Access Aeroelastic investigation of conventional fixed wings and bio-inspired flapping wings by analysis and experiment.(2018-09) Li, Hao; Guo, Shijun J.In this thesis, the structure and aeroelastic design, analysis and optimization of conventional fixed wing is firstly addressed. Based on the study results of conventional fixed wing, the study then focuses on the more complicated aerodynamics and aeroelasticity of flapping wing Micro Air Vehicles (MAV). A Finite Element (FE) model of a composite aircraft wing is firstly used as case study for the aeroelasticity of conventional fixed wing. A MATLAB-NASTRAN interfaced optimization platform is created to explore the optimal design of the wing. Optimizations using the developed platform show that 13% of weight reduction can be achieved when the optimization objective is set to minimize wing weight; and 18.5% of flutter speed increase can be achieved when aeroelastic tailoring of composite laminate layups is carried out. The study results further showed that the most sensitive part of the wing for aeroelastic tailoring is near the engine location, which contributes to the majority of flutter speed increment for optimization. In order to facilitate the structural design of non-circular cross section fuselage of Blended-Wing-Body (BWB) aircraft, an analytical model of 2D non-circular cross section is developed, which provides efficient design and optimization of the fuselage structure without referring to FE models. A case study based on a typical BWB fuselage using the developed model shows that by optimizing the fuselage structure, significant weight saving (17%) can be achieved. In comparison with the conventional fixed wing, insect flapping wings demonstrate more complicated aerodynamic and aeroelastic phenomena. A semi-empirical quasi-steady aerodynamic model is firstly developed to model the unsteady aerodynamic force of flapping wing. Based on this model, the aerodynamic efficiency of a Flapping Wing Rotor (FWR) MAV is investigated. The results show that the optimal wing kinematics of the FWR falls into a narrow range of design parameters governed by the dimensionless Strouhal number (St). Furthermore, the results show that the passive rotational of the FWR converges to an equilibrium state of high aerodynamic efficiency, which is a desirable feature for MAV applications. Next, the aerodynamic lift coefficient and efficiency of the FWR are calculated and compared with typical insect-like flapping wings and rotary wing. The results show that the aerodynamic efficiency of FWR in typical wing kinematics is higher than insect-like flapping wings, but slightly lower than the conventional rotary wing; the FWR aerodynamic lift coefficient (CL) surpassed the other wings significantly. Based on the numerical results, the study then continued to experimental investigations of the FWR. A prototype FWR model of weight 2.6g is mounted on a load cell to measure the instantaneous lift production. The kinematics of the wing is captured using high speed camera. Aeroelastic twist of the wing is measured using the resulting wing motion. Analyses by CFD and the quasi-steady aerodynamic model is then carried out and compared with experimental results. The study revealed that passive twist of the FWR wing due to aeroelastic effects forms desirable variations of wing Angle of Attack (AoA), which improves the aerodynamic performance of FWR. The results of the thesis provide guidance for structural, aerodynamic and aeroelastic design, analysis and optimization of conventional fixed wing, as well as bio-inspired flapping wing MAVs.Item Open Access Aeroelastic simulation of rotorcraft propulsion systems(2017) Castillo Pardo, Alejandro; Pachidis, VassiliosA close relationship between the aerospace technology level and the capability to model and simulate the physics involved during the flight has been identified throughout the aviation history. The continuous improvement in physical and mathematical models has provided a further understanding of the behaviour of the different components along with the complete vehicle. As a result, the performance modelling has experienced a large improvement. The aviation industry, which is characterised by the use of cutting edge technology, requires large investments when new concepts are introduced. The application of high fi delity simulation tools reduces considerably the investment carried out prototyping and testing. This fact is also applicable to the rotorcraft industry, where a continuous increase in the employment of helicopters has been observed throughout the last decades, expecting a sharp growth within the next 20 years. The forecasted growth in the number of helicopter operations along with the increasing concern about the environmental impact of aviation, lead the governmental bodies to set up a number of goals to reduce the carbon dioxide, nitrogen oxides, and noise emissions. Three paths were identified to reduce the environmental impact and meet the proposed goals. The fi rst one is the reduction in the number of operations. However, a sharp growth in the number of helicopter operations is expected. The second one is the optimisation of the flight procedures. Nevertheless, the potential improvement is limited. The third one is the introduction of a quieter and more,efficient type of rotorcraft. There exist two new rotorcraft con figurations which show enough potential to be studied. These are the tilt-rotor and compound helicopter. Both designs improve the cruise performance using auxiliary lift and propulsive systems, while they still exploit the vertical flight capability of helicopters. Nevertheless, the lack of reliable high fi delity models has made their development long and highly expensive. Within this context, the necessity of a simulation framework able to simulate and predict the detailed performance of novel rotorcraft con figurations is highlighted. The present work aims to lay the foundations of this comprehensive rotorcraft code by developing a computational framework for the aeroelastic simulation of propulsion systems. The tool is characterised by a high fi delity level able to predict the highly unsteady loads at a low computational cost. The fi rst characteristic makes this tool suitable for the design stage and noise calculations; whilst the second one enables its integration into multidisciplinary optimisation procedures. The development of this framework has required a considerable contribution to the knowledge in different areas of study, these included: structural dynamics, in flow aerodynamics, blade aerodynamics, aeroelasticity, and computational acceleration techniques. The individual models have been integrated into a cost efficient aeroelastic simulation framework, which has been extensively validated with experimental data. Very good and in some cases excellent correlation with the experimental measurements has been observed. The main contribution of this work has been the successful development of a computational framework for the aeroelastic simulation of rotorcraft propulsion systems. It accurately simulates and predicts the aerodynamic flow field and the unsteady loads generated by the rotor and transferred to the fuselage. It is easily expandable to account for interactions with other rotors, auxiliary lift surfaces, and fuselage bodies. The simulation tool estimates high fidelity low and high frequency aerodynamic loading, which enables the calculation of impulsive noise emissions. The framework computes accurate predictions of rotor power required, which enables its use as a validation tool for lower order models. The developed framework approximates the third level of Padfi eld's hierarchical paradigm, providing detailed aeroelastic information necessary for design purposes. The additions of parallel computing and an acceleration scheme results in a highly computationally effcient tool suitable for optimisation methodologies. Moreover, a considerable contribution has been made in terms of modelling of: coupled modal characteristics, aeroelastic simulation; computational enhancements of in flow models and investigation of the effect of the fuselage aerodynamic interference and coupled flexible blade modelling.Item Open Access Aircraft assembly process design for complex systems installation and test integration.(Cranfield University, 2019-04) Li, Tao; Lockett, Helen L.; Lawson, CraigThe assembly line planning process connects product design and manufacturing through translating design information to assembly integration sequence. The assembly integration sequence defines the aircraft system components installation and test precedence of an assembly process. From a systems engineering view point, this activity is part of the complex systems integration and verification process. At the early conceptual design phase of assembly line planning, the priority task of assembly process planning is to understand product complexities in terms of systems interactions, and generate the installation and test sequence to satisfy the designed system function and meet design requirements. This research proposes to define these interactions by using systems engineering concept based on traceable RFLP (Requirement, Functional, Logical and Physical) models and generate the assembly integration sequence through a structured approach. A new method based on systems engineering RFLP framework is proposed to generate aircraft installation and test sequence of complex systems. The proposed method integrates aircraft system functional and physical information in RFLP models and considers these associated models as new engineering data sources at the aircraft early development stage. RFLP modelling rules are created to allow requirements, functional, logical and physical modes be reused in assembly sequence planning. Two case studies are created to examine the method. Semi- structured interviews are used for research validation. The results show that the proposed method can produce a feasible assembly integration sequence with requirements traceability, which ensures consistency between design requirements and assembly sequences.Item Open Access Aircraft engine transient performance modelling with heat soakage effects(Cranfield University, 2019-11) Li, Zhuojun; Li, YiguangTransient performance design and assessment is a very crucial step of aircraft engine development, especially for acceleration and deceleration process. Normally, the assessment of transient performance stability would be done during the detained design stage while component design parameters are available. As a result, design iterations might be necessary and costly if the transient performance assessment is not satisfactory. To make engine design more cost and time efficiently, it has become more and more important to assess the transient performance stability at conceptual and preliminary design stage with the inclusion of key impact factors such as fuel control schedule, rotor dynamics, volume dynamics and heat soakage. However, due to the lack of detailed engine structural and geometrical information at the initial design stage, such transient performance simulation and assessment may have to ignore heat soakage effects. Therefore, in this paper, a novel generically simplified heat soakage and tip clearance model for three major gas path components of gas turbine engines including compressors, turbines and combustors and has been developed to support more realistic transient performance simulation of gas turbine engines at conceptual and preliminary design stage. Such heat soakage model including heat transfer and tip clearance only requires thermodynamic design parameters as input, which is normally available during such design stages. This generic heat soakage method has been applied to two engine models to test its effectiveness through an in-house developed performance code. The case study of heat-soakage effects could demonstrate that results are promising and the simplified heat soakage model is satisfactory.Item Open Access Alignment measurements uncertainties for large assemblies using probabilistic analysis techniques.(2017-12) Doytchinov, Iordan; Tonnellier, Xavier P.; Almond, HeatherBig science and ambitious industrial projects continually push forward with technical requirements beyond the grasp of conventional engineering techniques. Example of those are ultra-high precision requirements in the field of celestial telescopes, particle accelerators and aerospace industry. Such extreme requirements are limited largely by the capability of the metrology used, namely, it’s uncertainty in relation to the alignment tolerance required. The current work was initiated as part of Maria Curie European research project held at CERN, Geneva aiming to answer those challenges as related to future accelerators requiring alignment of 2 m large assemblies to tolerances in the 10 µm range. The thesis has found several gaps in current knowledge limiting such capability. Among those was the lack of application of state of the art uncertainty propagation methods in alignment measurements metrology. Another major limiting factor found was the lack of uncertainty statements in the thermal errors compensations applied to assembly’s alignment metrology. A novel methodology was developed by which mixture of probabilistic modelling and high precision traceable reference measurements were used to quantify both measurement and thermal models compensation uncertainty accurately. Results have shown that the suggested methodology can accurately predict CMM specific measurement uncertainty as well as thermal drift compensation made by empirical, FEM and FEM metamodels. The CMM task-specific measurement uncertainties made at metrology laboratory were validated to be of maximum 7.96 µm (1σ) for the largest 2 m assemblies. The analysis of the results further showed how using this method a ‘virtual twins’ of the engineering structures can be calibrated with the known uncertainty of thermal drift prediction behaviour in the micrometric range. Namely, the Empirical, FEM and FEM Metamodels uncertainties of predictions were validated to be of maximum: 8.7 µm (1σ), 11.28 µm (1σ) and 12.24 µm (1σ).Item Open Access Analysis of the effect of impact damage on the repairability of CFRP composite laminates.(2017-02) Alzeanidi, Nasser; Ghasemnejad, HessamPolymer composite materials are common in the aerospace application such as aircraft structures including primary and secondary structures. Therefore, there has been an increasing demand for composites in both the military and civilian aircraft industry. At least 50% of the next generation of military and civil aircraft structures are likely to be made from composites. The most important properties for composite materials in aircraft application was the high strength-to-weight ratios, stiffness-to-weight ratios and easy to repair. However, the composite materials have low resistance for impact damage. Impact can lead to significant strength reduction in aircraft structure about 40% to 60% of an undamaged composite laminate strength. Therefore, establish a numerical methodology to defined the optimum repair joint to restore sufficient strength of damaged aircraft composite structures during some operations and exercise activities with limited resources which will be the main contributions to knowledge in this thesis. To achieve this contribution need to understanding of the behaviour of Carbon Fibre Reinforced Plastic (CFRP) composite laminates subject to high velocity impact and the unrepaired composite laminates and repaired (stepped joint) subject to compression after impact test. Therefore, this study consists of two parts:- first, part a combined of numerical simulation and experimental investigation have been used to evaluate the woven CFRP laminate subject high velocity impact. The selected impact velocities were (140m/s, 183m/s, 200m/s, 225m/s, 226m/s, 236m/s, 270m/s, 305m/s, 354m/s and 368m/s) in order to evaluate the induced impact damage in three different thickness of CFRP composite laminates (6 mm, 4.125 mm and 2.625 mm) these velocities were selected according the gas gun limitation. The woven composite laminate made of Hexcel G0926 Carbon Fabric 5 harness 6K, Areal Weight 370 gsm. The resin used was Hexcel RTM 6, cured for 1 hour 40 minutes at 180° C at a pressure of 100 psi, with an average thickness of 0.375mm. The laminates were comprised of 16 layers, using the following stacking sequence: [(0/90); (±45); (±45); (0/90); (±45); (±45); (0/90); (0/90); (±45); (0/90); (±45); (0/90); (±45); (0/90); (±450); (0/90)], 11 layers, using the following stacking sequence: 0/90; ± 45; 0/90; ± 45; 0/90; ±45; 0/90; ± 45; 0/90; ±45; 0/90 and 7 layers, using the following stacking sequence: ± 45; 0/90; 0/90; ±45; 0/90; 0/90; ±45. The density of woven CFRP laminates was 1.512e-3 ±1e-6 grm/mmÖ³. The penetration process and also change of kinetic energy absorption characteristics have been used to validate the finite element results. The experimental and numerical method in this study show a significant damage occurs, including delamination, compression through thickness failure, out-of-plane shear failure and in-plane tensile failure of the fibres located at the rear surface when the projectile penetrates the laminate. The penetration mechanism of the projectile had a “plugging-type” (shear) failure and the hole that was formed after impact was conical in shape were shown in experimental and also verified in the numerical model. The residual kinetic energy in numerical model is 5.0 % larger than experimental data which is significantly matched in all simulated cases. In part two a finite element model is established to optimise the repair joint to restore sufficient strength of damaged composite laminate and used compression after impact test to compare the compression failure load of the sample. In order to achieve this an optimised repair models of stepped lap joints with variable parameters such as number of steps and length of steps have been experiment the undamaged composite laminate and composite laminate subject to high velocity impact and also created a numerical model for these experimental. The experimental CAI failure load of undamaged 7 Plies CFRP composite laminate higher than the failure load of damaged specimens by approximately 23%. The undamaged 11 Plies CFRP composite laminate failed at approximately 40% higher than the damaged specimens. Moreover, the difference between the experimental and numerical results of above tests was about 10%. The numerical model of repaired composite laminate show the damage initiated at the end of overlap and the average compression failure load of the stepped lap joint increased with the increasing of the number of step and length of step. The 85% and 90% of compressive failure load has been restored.Item Open Access Analysis of the evolution of aerospace manufacturing ecosystems(Cranfield University, 2020-06) Luna Andrade, Jose Junior; Salonitis, Konstantinos; Brintrup, AlexandraThe aerospace manufacturing industry is predicted to continue growing. Understanding its evolution is thus essential to prepare optimal conditions to nurture its growth. This research aims to help the growth of emerging aerospace ecosystems by identifying evolution patterns and categorising key enablers that have encouraged the growth of developed ones. The term aerospace ecosystem is used to embrace all the business activities and infrastructure that are related to the entire aerospace’s supply chain in a specific country. Inspired by studies that have successfully combined economics and network science, in this research, bipartite country-product networks are developed based on trade data over 25 years. The United Kingdom (UK), the United States of America, France, Germany, Canada and Brazil’s are first analysed as evidence suggests that their aerospace ecosystems are within the most developed in the world. Then, China and Mexico’s networks are analysed and compared with developed ones, as these countries have evidenced emergent aerospace ecosystems. Results reveal that developed ecosystems tend to become more analogous, as countries lean towards having a revealed comparative advantage (RCA) in the same group of products. Further analysis shows that manufactured products have a stronger correlation to an aerospace ecosystem than primary products; and in particular, the automotive sector shows the highest correlation with positive aerospace sector evolution. Key enablers related to the growth of the UK and Mexico’s aerospace ecosystems are identified and categorised using interpretive structural modelling (ISM) and cross-impact matrix multiplication applied to classification (MICMAC) methodologies. Results evidence relevant differences in the categorisation of key enablers among a developed and emergent aerospace ecosystems. On the other hand, it was identified that geopolitical factors and the automotive ecosystem are underpinning enablers for both aerospace ecosystem’s evolution. The final aim is that results of this research could be implemented on emerging aerospace ecosystems by emulating the patterns and key enablers that have characterised the evolution of developed aerospace ecosystems.