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Effect of the combined use of cryogenic + aging treatment on mechanical and damping property of Mn-Cu alloy based on response surface model
Get PDFIn this paper, the response surface method (RSM) is used to model the response surface between the target values and the cryogenic + aging treatment parameters. The effects of cryogenic + aging treatment on microstructures, mechanical, and damping properties of Mn-20Cu-5Ni-2Fe alloy are then investigated. The outcome indicates cryogenic + aging treatment can effectively enhance both mechanical and damping properties, and the optimum parameters cryogenic (-196 °C/30 h) + aging (428 °C/2 h) were obtained. The associated microstructural changes caused by the precipitated phase after the compound treatment resulted in an increase in the tensile strength from 358.3 MPa to 396.7 MPa, 38 MPa higher compared to that of the as-cast alloy. Meanwhile, it has the best damping property within a wide temperature range. At 50 °C, the internal friction value increased from 0.033 to 0.074, which was increased by 124 %. The damping strengthening mechanisms were discussed mainly from the perspective of the change in formation of {101} twins and motionable interface induced by fcc-fct transformation after the compound treatment. The obtained results provide a new reference for simultaneously improving mechanical and damping behaviors of Mn-Cu based alloys.The project was supported by the National Natural Science Foundation of China (Grant No. 52175410), Natural Science Research Program for Higher Educational Institutions in Jiangsu Province (Grant No.18KJB430009), Zhenjiang Basic Research Special Project (Grant No. JC2004010).Materials Today Communication
Advancing the synergy between models and experiments to investigate environmentally and mechanically driven crack propagation
Get PDFAero-gas turbine running temperatures are rapidly increasing in order to improve their
efficiency, and as a consequence components are subjected to more extreme environ-
ments. With higher operational temperatures and improved reliability, there is an in-
creased chance of both corrosion and mechanical degradation. In addition to operational
temperatures, the environment in which an aircraft flies has a significant effect on the
material life. Many contaminants are ingested by the engine and deposited on the turbine
blades, which often leads to surface degradation. Depending on the ingested contami-
nants, temperature, and applied stresses, cracking can be initiated and propagated rapidly.
This is particularly evident in the lower-shank regions of single-crystal nickel-based su-
peralloy blades, which have recently experienced significant cracking.
This study aims to understand the mechanisms behind crack propagation in single-
crystal nickel alloys exposed to intermediate temperatures, and when this propagation is
either mechanically or chemically driven. This research started by assessing crack inter-
action mechanisms that were hypothesised to be both stagnating and accelerating crack
growth, depending on specific length scales and crack formations. This was performed by
integrating available experimental data to calibrate a phase field model that could predict
the extension of cracks for different crack separations and layouts. The modelling results
clearly characterised the length scales needed to encourage crack shielding, and which
crack formations would see a stress intensification and consequently crack coalescence.
These results informed the decision to revisit the experimental setup to optimise which
experiments were performed. Using this newly developed methodology, the salt deposi-
tion method was amended with the aim of isolating the deposition sites to minimise crack
interaction mechanisms. The hypothesis was that significantly longer cracks would be ob-
ii
served if this could be achieved. This was performed for both the C-ring (at 550°C), and
corrosion-fatigue (at 700°C) tests. In the case of CMSX-4, the results were striking, with
the C-ring seeing cracks as much as ten times the size of those previously seen. CMSX-10
however, did not show a significant difference, as such, a microstructural characterisation
analysis was conducted, whereby the γ/γ′ structure for the two alloys was replicated from
microscopy data and further phase field models were run. The results showed that a more
regular structure was more resistant to crack propagation owing to the misalignment of
γ′ , which caused stress relaxation in the γ channel and at the interface.
Finally, this thesis shows how the model, once calibrated for one material and species,
can be used to approximate the response expected for another single-crystal nickel alloy
or a change in the embrittling species, while accounting for a degree of uncertainty. This
is not to say that modelling can or should replace experiments but rather to highlight
that preliminary modelling results can be used to build a test matrix that can reduce the
number of experiments that are run. It should be noted that this thesis does not focus on
the chemical/corrosive aspects in much detail, but rather investigates the importance of
stress. This thesis summarises the importance of integrating modelling, microscopy, and
experiments to set and answer hypotheses more efficiently.Engineering and Physical Sciences Research Council (EPSRC)PhD in Manufacturin
Techno-economic and environmental assessment of battery integrated wind farm siting across offshore Nigeria
Get PDFThis study investigates the economic, technical, and environmental impacts of integrating a battery energy storage system (BESS) with an offshore wind farm near Koko Sea Port, Nigeria. As renewable energy curtailment increases and Nigeria’s energy demand grows, energy storage systems (ESS) are essential for ensuring a firm power supply. While offshore wind farms have advanced globally, Nigeria remains underrepresented in related research. This study addresses this gap by presenting a comprehensive techno-economic and environmental assessment (TEEA) of an ESS-integrated wind farm along Nigeria's coast. The system includes 477 Siemens Gamesa SG 2.1-114 turbines, producing 930 GWh annually with an instantaneous output of 0.35 GW. Vanadium Redox Flow Batteries (VRFB) were identified as the most suitable ESS, providing 528 MWh of storage to maintain power during wind variability. Economic analysis indicates a Levelised Cost of Energy (LCOE) of 393.35 $/MWh, comparable to global 2020 benchmarks for newly commissioned offshore wind farms. Environmental analysis reveals significant carbon savings, with emissions reduced by over 107% and 74% relative to coal and gas power plants. This study highlights the potential of battery-integrated offshore wind farms to advance Nigeria’s clean energy transition, offering insights for policymakers and stakeholders pursuing sustainable development and Paris Agreement commitments.African Journal of Science, Technology, Innovation and Developmen
Intelligent multi-fault diagnosis for a simplified aircraft fuel system
Get PDFMachine learning (ML) techniques are increasingly used to diagnose faults in aerospace applications, but diagnosing multiple faults in aircraft fuel systems (AFSs) remains challenging due to complex component interactions. This paper evaluates the accuracy and introduces an innovative approach to quantify and compare the interpretability of four ML classification methods—artificial neural networks (ANNs), support vector machines (SVMs), decision trees (DTs), and logistic regressions (LRs)—for diagnosing fault combinations present in AFSs. While the ANN achieved the highest diagnostic accuracy at 90%, surpassing other methods, its interpretability was limited. By contrast, the decision tree model showed an 82% consistency between global explanations and engineering insights, highlighting its advantage in interpretability despite the lower accuracy. Interpretability was assessed using two widely accepted tools, LIME and SHAP, alongside engineering understanding. These findings underscore a trade-off between prediction accuracy and interpretability, which is critical for trust in ML applications in aerospace. Although an ANN can deliver high diagnostic accuracy, a decision tree offers more transparent results, facilitating better alignment with engineering expectations even at a slight cost to accuracy.Algorithm
Multi-agent deep reinforcement learning-based key generation for graph layer security
Get PDFAll research work was conducted whilst all authors were at Cranfield University.Recently, the emergence of Internet of Things (IoT) devices has posed a challenge for securing information and avoiding attacks. Most of the cryptography solutions are based on physical layer security (PLS), whose idea is to fully exploit the properties of wireless channel state information (CSI) for generating symmetric keys between two communication nodes. However, accurate channel estimation is vulnerable for attackers and relies on powerful signal processing capability, which is not suitable for low-power IoT devices. In this paper, we expect to apply graph layer security (GLS) to exploit the common features of physical dynamics detected by IoT sensors placed in networked systems to generate keys for data encryption and decryption, which we believe is a new frontier to security for both industry and academic research. We propose a distributed key generation algorithm based on multi-agent deep reinforcement learning (MADRL) approach, which enables communication nodes to cooperatively generate symmetric keys based on their locally detected physical dynamics (e.g., water/gas/oil/electrical pressure/flow/voltage) with low computational complexity and without information exchange. In order to demonstrate the feasibility, we conduct and evaluate our key generation algorithm in both a simulated and real water distribution network. The experimental results show that the proposed algorithm has considerable performance in terms of randomness, bit agreement rate (BAR), and so on.This work has been supported by the PETRAS National Centre of Excellence for IoT Systems Cybersecurity, which has been funded by the UK EPSRC under grant number EP/S035362/1.ACM Transactions on Privacy and Securit
Switched reluctance motor actuating systems for multirotor air vehicles
Get PDFAmong the race to net zero emissions, new vehicle concepts are thriving. Multirotor air
vehicles are popular for consumer-grade applications like sport or photography, but they
are also considered to solve the challenges of Urban Air Mobility. By analysing the multirotor vehicles and their typical faults, the highest severity of faults is attributed to the
actuating system, of which the central component is the electric motor. Comparing avail-
able technologies, switched reluctance (SR) motors are deemed a promising solution due
to their high degree of fault-tolerance, ruggedness, sustainability and the lack of permanent magnets. Therefore, this study presents a process of designing an SR motor actuating
system for use in multirotor vehicle applications. The efforts are focused on achieving
desired functionality and documenting technical challenges, rather than achieving an optimal design.
A pre-study on multirotor vehicle sizing methodology based on databases of off-the-
shelf components is presented. This is then expanded to cover systems with electric motors in general. Based on sizing specifications, a set of SR motors is optimised for a range
of vehicle weights. One design (corresponding to 8 kg quadrotor vehicle) is chosen for
further analysis and manufacture. A PI controller-based control solution is developed and
implemented, along the model of the whole actuating system in a simulator. Simulated
performance is compared with that of a reference BLDC motor actuating system. In addition, system behaviour is analysed in the presence of uncertainties and injected faults.
Results are expressed in terms of Loss of Effectiveness (LOE) metric used for the development of fault-tolerant control. The SR motor actuating system is then verified to be of
adequate performance and good fault-tolerance, especially against open circuit faults in
one or two phases. However, the system was found to be susceptible to position sensing system failure. In a preliminary comparison with BLDC motor actuating systems,
the designed system is comparable in terms of performance, advantageous in terms of
fault-tolerance and of considerably higher weight, which is attributed to immaturity of
the technology. Sources of the SR motor system advantages are identified as reluctance
torque and separation of phases, and recommended for further study.PhD in Aerospac
An experimental investigation of a full-scale aircraft ECS
Get PDFAli, Fakhre - Associate SupervisorAircraft Environmental Control System (ECS) conditions hot bleed air and
regulates to the cockpit, cabin and avionics bay. It consists of multiple
subsystems which are prone to degradation and eventually failure. There has
been a number of incidents reported of sudden cabin pressure loss resulting in
emergency landing. Such incidents at high altitudes can be problematic.
Furthermore, the ECS has been reported to be a major driver for unscheduled
maintenance impacting the operating costs. The development of an accurate
diagnostic solution would identify the degradation early, hence, ensuring safety
and reduction in maintenance costs. Researchers in the past have adequately
studied model-based diagnostic techniques for the ECS at a component level.
However, the ECS being an integrated system, the interdependencies between
components makes the diagnosis difficult, particularly when the valves within the
ECS masks fault occurrences and the fault propagates through the system. For
this reason, IVHM centre has developed an ECS simulation model, SESAC,
which has the capability to perform healthy and component degradation
simulation. This PhD focuses on an experimental investigation on the ECS to
facilitate verification of SESAC. A novel ground test facility (GTF) is developed
on a Boeing 737-400 aircraft. The GTF is used to produce data under different
ambient and operating conditions, which is used for PACK performance analysis.
The importance of appropriate design of control system for ECS simulation model
has been highlighted in this research. Furthermore, aircraft data has been used
to provide understanding of the ECS control system. The control logic within
SESAC has been fine-tuned to support heat exchanger degradation and valve
malfunction simulation studies have been conducted. The ability of the 737-GTF
to capture fault occurrence has also been demonstrated using experimental data.PhD in Transport System
Potential for energy recovery of a nonadiabatic subsonic airfoil
Get PDFThis paper investigates the effect of wall temperature and flow conditions on the potential for energy recovery of the NACA0012 airfoil. A work–energy balance has been derived from the governing equations for moving control volumes for a body in dynamic equilibrium, aerodynamically decoupled from its propulsive source. The formulation has been applied to an extensive test matrix of computational fluid dynamics cases, with steady level flight imposed and wall temperature, angle of attack, Reynolds number, and Mach number varied independently. The decomposition of the wake energy shows explicitly that the near-field work of the body manifests as global energy constituents, viscous dissipation, and baroclinic work. The analysis identifies the conditions and underlying mechanisms that minimize and maximize the potential for energy recovery, revealing that there are synergistic opportunities for tightly coupled airframe and propulsor configurations with waste heat to reject.Journal of Aircraf
Floating solar wireless power transfer system for electric ships: design and laboratory tests
Get PDFThe maritime industry is under increasing pressure to decarbonise, presenting an important pathway of transforming the power systems from conventional marine fuels to electric-based. This study proposes an innovative solution to support maritime decarbonisation through the integration of a floating solar clean energy harnessing and wireless power transfer (WPT) technology for electric vessels. The paper presents the design and experimental tests of the integrated system specifically, based on a model of an electric yacht. This study provides an in-depth analysis of application of floating solar to provides an off-grid wireless power transfer system that can scale for larger vessels such as ferries. The off-grid modularity proposed enables scalable, flexible, and sustainable energy delivery for maritime applications and decarbonisation with specific attention to challenges in WPT alignment and environmental condition. Simulations using ANSYS Maxwell were performed to model the magnetic field interactions and ascertain the optimal power transfer efficiency. Subsequently, a reduced-scale prototype system was designed, built and tested in a wave tank. The experimental results demonstrated efficient wireless charging with an average efficiency of 82 %, and the docking system proved effective in maintaining alignment even when the ship has wave-induced motions. The findings support the feasibility of using floating solar WPT systems for maritime vessels and pave the way to larger-scale studies.This work is part of a project that has received funding Transport Research and Innovation Grants supported by UK Department for Transport and Connected Places Catapult under Grant Agreement No. TRIG2023-30066 - Design of a floating solar charge station for the electric vessels at the Port of Dover.Energy Conversion and Managemen
Navigating barriers to decarbonisation of UK’s aviation sector through green hydrogen: a multi-scale perspective
Get PDFAviation is widely recognised as one of the most carbon-intensive modes of transport and among the most challenging sectors to decarbonise. The use of green hydrogen (H2) in airside operations can help reduce emissions from air transport. While the pace and scalability of technology development, including H2-powered and ground support equipment, will be key factors, other financial, regulatory, legal, organisational, behavioural, and societal issues must also be considered. This paper investigates the key opportunities and challenges of using H2 in the aviation industry through eleven semi-structured interviews and a virtual expert workshop (N = 37) with key aviation industry stakeholders and academia. The results indicate that, currently, decarbonisation of the aviation sector faces several challenges, including socio-technical, techno-economic, and socio-political challenges, with socio-technical challenges being the most prominent barrier. This study shows that decarbonisation will not occur until the UK government is ready to have all the required infrastructure and capacity in place. Governments can play a significant role in directing the necessary ‘push’ and ‘pull’ to develop and promote zero-carbon emission aircraft in the marketplace and ensure safe implementation.This research was funded by the UK Department for Transport (DfT) and the Connected Places Catapult through the Transport Research and Innovation Grants (TRIG) programme as part of the Zero Emission Flight Infrastructure (ZEFI) initiative, under the project “Low Carbon Energy Demand Scenarios for Aviation (LOCESA)”Sustainabilit