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ItemReview on properties, physics, and fabrication of two-dimensional material-based metal-matrix composites (2DMMCs) for heat transfer systems(Elsevier, 2025)In the exploration of new materials development, 2D materials have received much attention due to their outstanding properties in terms of e.g. strength, and electrical and thermal conductivities. Graphene and boron nitride, amongst other 2D materials, are renowned for their exceptional thermal conductivity. In this review, we examine the properties, physics, and fabrication techniques of 2D material-based metal-matrix composites (2DMMCs) with a specific focus on heat transfer systems. The on-going demand for better electronic cooling systems in combination with advancements in mass production techniques of 2D materials facilitates the application of 2DMMCs in heat transfer systems. However, currently, the thermal behaviour of 2DMMCs remains largely uncategorized, strengthening the timely context of this review. Next to recent research progress, material properties, production techniques and strategies for improving thermal conductivity of 2DMMCs are addressed in this work. Methods to reliably assess the thermal conductivity of 2D enhanced materials are discussed alongside the fabrication techniques for 2D-material feedstocks for 2DMMCs production. Also, current limitations in the heat transfer capabilities of 2DMMCs, alongside prospects for enhancing thermal properties through emerging technologies, such as additive manufacturing, are addressed.
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ItemThe role of scan strategies in fatigue performance for laser powder bed fusion(Elsevier, 2020)The integrity of additively manufactured components is limited by the number, size, type and location of defects encapsulated in the build. Our ability to manufacture fatigue resistant components by the powder bed fusion process is still nascent as a result. The location of defects within a build volume is known to be of significance but efforts are yet to achieve superior manufacturing strategies resulting in tolerable fatigue performance. In this work the role of laser scan strategies is investigated in determining fatigue performance of printed components. Fractography and X-ray computed tomography data are presented to support this.
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ItemAnalytical LPBF Melt Pool Simulation and Experimentation for Metamaterial Lattices(Scipedia, 2025)Laser Powder Bed Fusion (LPBF) has emerged as a pivotal additive manufacturing technique, enabling the fabrication of complex geometries with high precision. Metamaterial lattices, characterized by architected periodic structures, have garnered significant interest due to their unique mechanical properties and potential applications across various engineering domains. Sizing of the lattice struts requires accurate prediction of the melt pool geometry. In particular, unsupported overhanging struts, exemplary for auxetic lattice structures, are challenging to fabricate with consistent quality. Traditional finite element analysis are computationally intensive and may not be practical for optimization. Analytical models offer a more efficient approach to predict melt pool characteristics, yet their application to the fabrication of complex metamaterial lattices remains underexplored. In this study, we present an analytical model tailored to predict melt pool dimensions specific to the fabrication of metamaterial lattices using LPBF. Our model integrates key process parameters, including laser power, scanning speed and material properties, to estimate melt pool width, depth and length. The model has been validated for stainless steel 316L based on thin-walled structures. To predict the processability of unsupported overhanging structures, the thermal behaviour of consolidating directly on powder has been considered. Results show that in particular the melt pool depth and most significantly the length are influenced. LPBF experiments have been conducted, in which horizontally overhanging struts are fabricated. The experimental results show agreement with the predictions of our analytical model with deviations within understandable margins. Subsequently, optimal LPBF process parameters were select to successfully fabricate a number of metamaterial lattice structures, including hard-to-print auxetic structures. Our findings provide valuable insights into the complex relationships between LPBF process parameters and resulting melt pool geometry. The models rapid predictive capabilities make it a valuable asset for selecting optimal parameters, reduce extensive empirical testing and enable the fabrication of high-quality metamaterial lattices.
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ItemConstraints on Recoil Leader Properties Estimated from X-ray Emissions in Aircraft-Triggered Discharges(AGU, 2020)During Airbus aircraft campaigns flying into thunderstorms in 2014–2016, X-rays were observed during two stages of aircraft-triggered lightning: nanosecond pulses of X-rays associated with negative leader steps and bursts of X-rays during recoil events. This work will focus on the observations of X-ray bursts associated with recoils. Recoils are observed as microsecond-fast changes in the local electric field, associated with large currents passing through the aircraft, and are found to sometimes be associated with bursts of X-rays. From over 200 aircraft-triggered lightning strikes, 54 recoil events were found to be associated with microsecond bursts of X-rays. The majority of the bursts consist of 1–3 X-ray pulses, with some bursts containing as many as 29 X-ray pulses. We compare the observed superposed X-ray spectrum with modeled spectra using a GEANT4 model of the detector and aircraft, to determine the source potential needed to accelerate the electrons that produce the observed X-rays. A model of the recoil leader was made to determine the gap distance and gap potential between the recoil leader and the aircraft. From the modeling, we determine a solution space for the gap and leader lengths where the gap length is constrained by the observed minimum and maximum times between the onset of the X-ray pulses and the onset of the current pulses detected at the aircraft (1 to 93 m). We also find two constraints from the fitting of the modeled spectra to the superposed spectrum, limiting the leader length to between 1 and ∼240 m.
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ItemEvaluating Sensor Performance for Impact Identification in Composites: a Comprehensive Comparison of FBGs with PZTs(SAGE, 2024)Aerospace composite components require effective monitoring techniques to detect possible internal damage from impact events. To ensure reliable impact identification, sensor measurements can provide valuable information about impact energy and identify potential issues that may require further investigation. However, selecting the most appropriate sensor technology to measure impact force and energy is a challenge. In this article, a systematic and structured approach is presented to compare the expected performance of sensors and their metrological parameters in terms of their ability for impact identification in aerospace composites. The proposed methodology is demonstrated using an application example where fibre Bragg grating (FBG) are compared with piezoelectric (PZT) sensors through comprehensive tests. These tests include the correlation test, the sensitivity test, and the factor test. The correlation test showed a high agreement between FBG and PZT sensors in the time and frequency domain. The sensitivity test indicated a significant correlation between the signal features and the impact energy levels in the energy profiling diagrams, revealing nonlinearities and energy losses indicative of damage. Furthermore, these results emphasise the superior resolution of the FBG sensors and the comparable repeatability of the two sensor types. Finally, the factor test showed that FBG sensors are sensitive to different angles of incidence, while PZT sensors have a more stable directivity. Further analysis also showed that the signal strength of both sensor types decreases with increasing distance from the impact source. Overall, the proposed approach enables a thorough evaluation of the capabilities and limitations of both sensor types. Consequently, it provides information to make an informed decision on the most suitable sensor for impact monitoring systems.