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Printing powerful powders: evaluating static and dynamic behaviour
Get PDFAdditive Manufacturing (AM), commonly referred to as 3D printing, is a promising manufacturing technique, enabling near full control of the final product’s properties. With its unique approach to complex objects manufacturing, AM is investigated for its suitability of manufacturing with a wider range of materials. Despite the global research on AM of Energetic Materials that has already been conducted, final energetic devices often offer poorer product performance, compared to traditional manufacturing techniques.
Reasoning for poorer outcomes could be attributed to the need for adapting and modifying Energetic Materials for AM purposes. To make the materials suitable for AM, there is a need for material modification, such as mixing energetic ingredient with solvent or binder, both of which often result in reducing the desirable outcome: the use of solvent can lead to uneven drying and shrinkage (and therefore producing voids within the product); too much binder is often responsible for low energetic density, therefore causing high burn rates and detonation velocities to be inaccessible. To overcome that, it would be beneficial to use raw, unmodified Energetic Materials – in their powdered form.
Research conducted at Cranfield University, using Dry Powder Additive Manufacturing has proven, that energetic devices can be successfully printed using energetic powders. However, working with powders is often challenging: a lack of continuous flow, powder caking or powder-dispensing nozzle blockages are often experienced. To maximise the final product performance and avoid above issues, it is necessary to understand powder behaviour: its dynamic flow, bulk, shear and process properties. A deep understanding of those properties and their effect on manufacturing process is a crucial step to further developing this AM technique.
Current methods of powder characterisation are typically limited to determination of 3 parameters: Angle of Repose, Carr (Compressibility) Index and Hausner Ratio. Scientific community have, however, proven these methods to be unreliable, proposing more thorough ways of powder studies: powder rheometers. Despite their growing popularity, analysis and interpretation of test results can still pose some challenges.
Current research focuses on gaining better understanding of powder rheology and recognising how investigated powders’ properties translate to their behaviour during the printing process.Defence Equipment & Support (DE&S)Defence and Security Doctoral Symposia 2024 (DSDS24
Atmospheric pressure plasma etching of Ti-6Al-4V using SF₆
Get PDFAtmospheric pressure plasma (APP) etching using SF₆ has been shown to etch Ti-
6Al-4V (Ti64). Operating parameters for input power, SF₆ concentration and standoff
distance were determined through previous work as 1.2 kW, 0.8 L min⁻¹ and 6mm
respectively as the optimum values for etching using the Helios 1200 machine. By using
various surface characterisation techniques, information over a broad range of spatial
frequencies was obtained. By conducting stationary, dynamic and areal etching, the
process has been shown a high degree of precision and material removal rates varying
from 0.5 mm3 min⁻¹ to 2 mm³ min⁻¹ . This process preferentially etches the BCC β phase
of Ti64 over the HPC α phase by∼50 %. It is proposed that this preferential etching
of the β phase is due to both the crystal structure strength being weaker than the α
phase and the BCC crystal structure being less dense than HPC, making it easier to
remove more volume of material. The etching process is highly temperature dependent
and preheating of the samples is required to achieve a clean trench. Significant amounts
of redeposition also remain on the surface <2 µm which comprise of mostly fluorine and
oxygen, but this is easily removed. The surface remains optically opaque after etching
due to significant roughening of the surface, however negligible contamination remains.
The proposed material removal mechanism is through the formation of volatile VFₓ and
TiF₄ compounds.Engineering and Physical Sciences Research Council (EPSRC)PhD in Manufacturin
WAAM-ViD: towards universal vision-based monitoring for wire arc additive manufacturing
No full textThe dataset generated for this study can be found in the WAAM-ViD repository (https://doi.org/10.57996/cran.ceres-2763), and the source code developed in this study can be found in GitHub (https://github.com/IFRA-Cranfield/WAAM-ViD).In the context of Industry 4.0, autonomous and data-driven manufacturing processes are advancing rapidly, with wire arc additive manufacturing (WAAM) emerging as a promising technique for producing large-scale metal components. Ensuring quality control and part traceability in WAAM remains an area of active research, as existing process monitoring systems often require operator intervention and are tailored to specific machine setups and camera configurations, limiting adaptability across industrial environments. This study addresses these challenges by developing an angle-invariant melt pool analysis pipeline capable of recognising bead features in wire-based directed energy deposition from monitoring images captured using various camera qualities, positions, and angles. A new benchmark dataset, WAAM-ViD, is also introduced to support future research. The proposed pipeline integrates two deep learning models: DeepLabv3, fine-tuned through active learning for precise melt pool segmentation (Dice similarity coefficient of 95.90%), and WAAM-ViDNet, a regression-based multimodal model that predicts melt pool width using the segmented images and camera calibration data, achieving 88.71% accuracy. The results demonstrate the pipeline’s effectiveness in enabling real-time process monitoring and control in WAAM, representing a step toward fully autonomous and adaptable additive manufacturing systems.Frontiers in Manufacturing Technolog
Dynamic Non-Binary Prioritisation for UTM Resource Allocation
Get PDFAdvanced air mobility (AAM) is set to revolutionise aerial operations, with uncrewed aircraft system (UAS) missions varying significantly in societal importance, urgency, and scheduling requirements. Existing regulatory frameworks, however, rely on static and binary prioritisation schemes which fail to address the complexity and diversity of UAS missions. This approach is particularly problematic in federated UAS traffic management (UTM) environments, where no single actor allocates interdependent resources. Notably, such environments often default to a first-come, first-served (FCFS) approach, leading to inefficiencies, delays, and suboptimal scheduling outcomes. This study thereby proposes a dynamic and non-binary prioritisation scheme to address the limitations of conventional static approaches. It defines the requirements and objectives of such a scheme, and contextualises the framework within a federated UTM architecture aligned with global concepts of operations (ConOps). Notably, extensive simulations confirm that non-binary priorities can effectively improve the success rate of socially critical missions in a federated UTM ecosystem. Moreover, focus groups with UTM stakeholders are leveraged to identify generic characteristics that may influence mission priorities, and expert-defined prioritisation functions are derived using a bespoke symbolic regression tool. Supervised learning through a Siamese network is further used to learn priority mappings from pairwise expert decisions. This data-driven technique is identified as a more practical approach to priority mapping, and shown to outperform expert-defined functions even in simple environments.The authors would like to thank the European Commission and the SESAR Joint Undertaking for the initiation and funding of the SAFIR-Ready project. The SAFIR-Ready project has received funding from the European Union's Horizon Europe research and innovation programme under grant agreement No. 101114855.2025 Integrated Communications, Navigation and Surveillance Conference (ICNS
Nacelle aerodynamic design and optimisation
Get PDFTejero Embuena, Fernando - Associate SupervisorFor a required thrust level, the reduction of the specific fuel consumption of an
aero-engine can be achieved through an improvement of the propulsive efficiency.
This is typically enabled by higher bypass ratios and lower fan pressure ratios.
This may result in a larger fan diameter that increases the overall aircraft drag
and weight as well as the interference effects between the engine and the airframe.
Additionally, the next generation of Ultra-High Bypass Ratio (UHBPR) aero-engines
are expected to be installed in a more close-coupled position with the airframe
due to multi-disciplinary constraints such as structural loads or ground clearance.
Consequently, the aerodynamic interference effects of the installation further increase
and the potential benefits of the new UHBPR aero-engine cycles might be eroded. As
a result, new design technologies that consider the engine coupled with the airframe
have to be developed.
The main focus of this project is on the aerodynamic shape design of compact
nacelles in an airframe-installed configuration. This is a challenging design problem
governed by computationally expensive numerical simulations, transonic non-linear
flow physics and a high dimensional design space. Moreover, this design problem
is typically subjected to computational constraints to meet industrial time scales.
Therefore, surrogate modelling techniques to accelerate the optimisation process are
a key aspect of the work. Single-fidelity and multi-fidelity surrogate models based
on Artificial Neural Networks and Kriging interpolation were assessed. While a
Reynolds-Averaged Navier-Stokes (RANS) Computational Fluid Dynamics (CFD)
method was used as high-fidelity, an inviscid CFD model was used as a low-cost,
low-fidelity method.
The research quantified the effect of key aspects in the installed nacelle design problem
such as the design variables considered, the surrogate modelling technique, the
sampling size of the design space and the CFD fidelity. From the traditional Eulerbased
method to assess the aerodynamic integration of the aero-engine in the airframe,
a key novel contribution of this research is a systematic evaluation of different
modelling approaches to quantify trades between aerodynamic performance and
computational effort. The work showed that the size of the design space population
for the surrogate models used, even with lower fidelity data, was the most important
parameter to determine the design space gradients and identify the optimum design.
At the same computational cost, the added complexity of multi-fidelity methods
provided no benefits. Overall, for the first time this research established that for
installed nacelle configurations, the industrial design problem is best addressed using
single-fidelity Kriging models based on Euler CFD data with a posteriori RANS
CFD evaluation of the optimal design. It was successfully shown that using this
novel approach the installed nacelle design could be improved to provide a 0.6%
reduction in cruise fuel burn, while also providing the design space maps to enable
trade studies on key nacelle geometric parameters.PhD in Aerospac
Visual-based automated aircraft inspections for 3d skin damage
Get PDFAvdelidis, Nico - Associate SupervisorVisual inspection is the common mean to detect damages on the aircraft skin. Standard maintenance programmes require engineers to perform frequent inspections that are
costly, time consuming, hazardous and subject to human factors. Engineers are required
to inspect all the areas, including crown, wings and vertical stabiliser, and personally
evaluate the damage. Dents, in particular, are flaws that are challenging to detect and
measure due to undefined boundaries, complex geometry and difficult access. Because of
these characteristics, dents cannot be detected by monocular cameras and automation of
their inspection has been lacking momentum, generally limited to manually operated 3D
scanning tools. Moreover, no solution has been explored to replace the human judgement
of the damage. The aim of this work is the design of an automatic system to inspect the
aircraft skin, identify dents, measure and report them to the engineer, thus demonstrating
the feasibility of such autonomous task via unmanned aerial vehicles. After reviewing the
state of the art, data is acquired by means of a single-shot structured-light algorithm for
3D scanning based on Fourier transform profilometry and compatible with the use of un-
manned aerial vehicles, yet delivering submillimetre accuracy. Machine learning is then
considered for the autonomous identification of dents, implemented through a novel point
cloud segmentation algorithm. Finally, a mathematical model is proposed to evaluate
dent shapes, replacing the current reporting standards by allowing accurate and comparable dimensional evaluation. The three main contributions operate together to enable
autonomous aircraft dent inspections, whose feasibility is demonstrated by experiments
with a prototype system. This work paves the way for future automated systems capable to increase safety and advance aircraft inspection reliability, while reducing human
workload, downtime and thus costs.PhD in Transport System
Integrated UAS platform with 5G technology and non-terrestrial networks: Orkney Islands scenario
Get PDFThe integration of fifth-generation (5G) technology with Non-Terrestrial Networks (NTN) holds transformative potential for Beyond Visual Line of Sight (BVLOS) operations of Uncrewed Aerial Systems (UAS) in rural regions. This paper presents a comprehensive architectural design that leverages satellite-enabled 5G networks to enhance connectivity in the Orkney Islands, Scotland, thereby improving the reliability and operational efficiency of UAS missions. By addressing the limitations of terrestrial networks, particularly in remote and underserved areas, the proposed flowchart ensures seamless data communication and transfer, facilitating real-time control and monitoring within the UAS platform. Simulations are conducted to validate the scenario for remote area connectivity. This work underscores the crucial role of NTN in advancing UAS operations, paving the way for innovative services and broader adoption of UAS technologies in rural settings.This work was supported by the Connectivity for Remote Orkney Future Transport (CROFT) project, which is funded by the European Space Agency (ESA) under the Advanced Research in Telecommunications Systems (ARTES) program.2024 IEEE Future Networks World Forum (FNWF
Computational fluid dynamics and adjoint-based optimization of a supersonic combustor for improved efficiency
No full textAdjoint-based optimization methods, that were previously in the realm of computational fluid dynamics (CFD) research, are now available in commercial software. This work explores the use of adjoint-based optimization to maximize mixing and combustion efficiencies for a supersonic combustor. To this end, a two-dimensional combustor was considered with parallel hydrogen injection. Simulations were carried out based on the steady Reynolds-Averaged Navier–Stokes equations and optimization was performed using a simplified passive scalar field instead of the full reactive flow problem. The optimization of a triangle-shaped mixing element is considered in addition to a case allowing the entire bottom of the combustor to deform. The relatively small mixing element could not boost efficiency significantly. By comparison, the optimization of the combustor wall resulted in both mixing and combustion efficiency gains accompanied by total pressure loss penalty. The optimization achieved higher efficiency compared to the baseline by extending the total volume of the reaction zone. The presented proof-of-concept results are relevant for the design of hypersonic vehicle propulsion systems, such as scramjets.Fluid
Towards strength–ductility balance in a Ti-6Al-4V alloy through microstructure optimization by composite hot forging and two-step annealing processes
No full textObjectives
Obtaining strength–ductility balance in titanium alloys remains a challenge to this day. In this work, we improve the strength–ductility synergy of a Ti-6Al-4V alloy through specialized hot forging and two-step annealing processes.
Methods
During hot forging, the large equiaxed grains undergo minimal change, while all the lamellar α grains spheroidize to fine equiaxed grains due to severe dynamic recrystallization. During subsequent annealing and water quenching, the large equiaxed grains remain unchanged, and the martensite transformation occurs within fine equiaxed grains, leading to the microstructures composed of large equiaxed grains and nanosized acicular α′ martensite grains in the water quenched (WQ) alloy.
Results and conclusion
Compared to the hot forged (FG) alloy, the WQ alloy exhibited a significantly increased tensile strength and a decreased elongation. The strengthening effect came from the high dislocation density, high-density grain boundaries, and dense twin boundaries in the region of α′ martensite. The short-time annealed (ST) alloy after the second-step short-time annealing then showed a similar grain size and morphology to the WQ alloy. However, the dislocation density in large equiaxed grains dramatically decreased. This caused an increased elongation without sacrificing strength compared with the WQ alloy, implying the superior strength–ductility balance.Composite Design and Manufacturin
Key elements to navigate sustainable product development in aerospace
No full textProduct development is critical for sustainable development, yet sustainable design practices remain under-implemented in the industry. This paper explores the aerospace sector, addressing its specific barriers and enablers to sustainable design. Through a comprehensive literature review, group discussions, and expert group interviews, this study introduces an impact model with essential elements for enabling sustainable product development in aerospace and explains their causal relations. Five key elements were identified: business drive, sustainability implementation, knowledge, ownership, and collaboration. In addition to the impact model, the paper discusses aerospace-specific challenges and opportunities for sustainable product development. Findings from this study offer a practical framework for practitioners and researchers to plan and implement interventions in organizations.We sincerely acknowledge the Swedish Innovation Agency Vinnova for funding this research, the focus group discussion participants at the EASN conference 2024, and GKN Aerospace and SAAB for their active participation.ICED25 - 25th International Conference on Engineering DesignProceedings of the Design Societ