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Optimization of crystal plasticity parameters with proxy materials data for alloy single crystals
Get PDFMultiscale modeling approaches have demonstrated ample value in understanding, predicting, and engineering materials response. While increasing computational power has aided in modeling atomic behavior from first principles, modeling mesoscale mechanisms such as intergranular failure or crack initiation still rely strongly on correlative models. Crystal Plasticity models have been extensively used to relate process-property-structure in metallic materials including mesoscale effects such as texture, microplasticity, and failure variability. However, models still suffer from low predictive power at the grain scale, which leads to poor damage prognosis outside the experimental calibration set. In addition to model form error, mesoscale uncertainty is dominated by an inadequate model parameterization that arises from calibration exclusively to macroscopic experimental data. This work explores parameter uncertainty in Crystal Plasticity models and proposes a hybrid physic-based and numerical optimization approach to identify parameters associated to mesoscale strengthening in FCC metals and alloys. The strength and novelty of the approach rely on calibrating parameters independently using single-crystal and polycrystal stress–strain curves. We further demonstrate that multiple materials can be incorporated simultaneously into a single optimization algorithm to robustly quantify mesoscale material-invariant parameters. These values are then used to blindly predict the response of single- and poly-crystals engineering alloys. As a result, our approach mitigates modeling uncertainty by augmenting the data for calibration with single crystal experiments from different materials with similar dislocation structures (i.e., proxy materials). The results provide the basis for a robust parameterization of crystal plasticity models that can predict single- and poly-crystal responses for engineering alloys even in the absence of direct experimental data.Engineering and Physical Sciences Research Council (EPSRC): grant EP/R034478/1.International Journal of Plasticit
Optimizing the mechanical properties of cement composite boards reinforced with cellulose pulp and bamboo fibers for building applications in low-cost housing estates
Get PDFAfrica is the third-richest continent in the world in terms of bamboo species. Despite these laudable natural resources, most African countries still use asbestos cement board as one of their major building materials. This is chiefly due to the high cost of equipment and technologies associated with non-asbestos-fiber cement board production. The current research seeks to underscore the possibility of utilizing these massive continent resources for non-asbestos-fiber cement board production by employing the existing production process in the asbestos cement industries via an innovatively developed laboratory-simulated Hatschek process. Non-asbestos-fiber cement boards incorporating kraft and bamboo fibers were successfully produced in the laboratory using this innovative method based on Hatschek technology, with natural fibre addition in the range of 2–6 wt.%. Experimental results revealed that the Flexural strength and deflection of the board improved significantly, producing optimum values of 10.41 MPa and 2.0 mm, respectively for composite board reinforced with 10 wt.% and 6 wt.% of kraft pulp and bamboo fibers, respectively. The SEM morphology of the fractured surfaces revealed the mode of composite fracture as well as good interaction at the fiber–matrix interface. Overall, the mechanical properties of the developed composite boards satisfy the minimum requirements of relevant standards based on fiber cement flat sheets and can be employed for internal building applications in low-cost housing estates in developing countries. The outcome of this research indicates that the current industrial production process based on Hatschek technology can be employed for non-asbestos-fiber cement board production using the studied natural fiber.This research was funded by the Tertiary Education Trust Fund (TETFund), Nigeria, through the Academic Staff Training and Development (AST&D) scholarship grant number TETF/ES/ UNIV/ONDO STATE/TSAS/2019/Vol.1.Material
Preliminary analysis of iron remnants from three archaeological sites in Central and Eastern Taiwan
Get PDFPresentationDuring the past few decades, it has been widely believed that bloomery artifacts found in Taiwan archaeology were locally produced, while cast iron might have been exchanged from mainland China. However, the argument needs refinement as cast iron has long been the dominant ironworking technology in China. Nevertheless, bloomery smelting technology has also been adopted in peripheral regions of China, leading to the establishment of several local workshops
Prediction of far-field noise from installed corrugated nozzles
Get PDFIn this study, a reduced order model, devised by Lyu and Dowling, is used to predict the farfield installation noise of corrugated nozzles installed beneath a NACA aerofoil. A complementary investigation, detailed in another paper, reveals that employing square corrugations near the nozzle lip diminishes jet-surface interaction (JSI) noise compared to a round 40-mm diameter nozzle. This reduction is particularly notable for Strouhal numbers ranging from 0.3 to 0.9 and at high polar angles. The near-field pressure data, required for Lyu and Dowling’s model, is gathered using a circular array consisting of eight 1/8-inch microphones in the Doak Laboratory, at the University of Southampton, UK. Generally, the predictions align well with the experimental trends for Mach numbers ranging from 0.4 to 1 under static ambient flow conditions. Furthermore, it is observed that a minimum of four azimuthal modes must be available to accurately predict the noise generated by the corrugated nozzles. The effects of free-stream Mach number, particularly focusing on the predictive capacity of Lyu and Dowling’s model, are also investigated. Quantitative agreement at Strouhal numbers between 0.1 and 0.5 in evidenced.This work is funded by the Innovate UK Research Programme FANTASIA - Future Aircraft Noise Technologies And Systems Integration Analytics (ref. 74217). The authors would also like to acknowledge the support provided by the Rolls-Royce University Technology Centre for Propulsion Systems Noise, within the Institute of Sound and Vibration Research at the University of Southampton. The first author would also like to thank the Federal University of Uberlandia.30th AIAA/CEAS Aeroacoustics Conference (2024
Hydroelastic modelling of a deformable wave energy converter including power take-off
Get PDFGiven the advantages of flexible wave energy converters (FlexWECs), such as deformation-led energy harnessing and structural loading compliance, there has been a significant interest in FlexWECs in both academia and industries. To simulate the FlexWEC interaction with ocean surface waves, a 3D computational fluid-structure interaction approach is developed in this study. The fluid and solid governing equations are discretized using finite difference and finite element methods, respectively. An immersed boundary method is used to couple the two independent grid systems. A novel numerical technique is introduced to model the dielectric elastomer generator (DEG) as the power take-off (PTO). The wave energy capture performance is analysed for different PTO configurations and at various wave conditions. Based on the obtained results, the PTO damping coefficient and the relative wavelength range that maximizes the capture width ratio (CWR) are determined. The wavefield results also reveal the presence of wave-height enhancement and attenuation points around a single FlexWEC, providing potential site selection references when deploying multiple FlexWECs in an array.Innovate UKL.H. acknowledges grants received from Innovate UK (No. 10048187, 10079774, 10081314), and the Royal Society (IEC\NSFC\223253, RG\R2\232462), and UK Department for Transport (TRIG2023 – No. 30066).Marine Structure
Dataset "Radar geometries used during the PhD of Alexander Hagelberg"
No full textThis excel file contains the co-ordinates used in the experiments of the PhD of Alexander Hagelberg. These trajectories were used in various papers which are listed in the headers.Defence Science and Technology Laboratory (DSTL
Navigating barriers to reverse logistics adoption in circular economy: an integrated approach for sustainable development
Get PDFAchievement of sustainability goals is an epic task for developing economies that still strive to fulfil their basic needs. The availability of limited resources in the developing world vis-à-vis the ever-increasing demand poses further challenges to developing economies willing to transition into circular economies. Reverse logistics (RL) can facilitate this transition towards a circular economy (CE) by maximising resource utilisation and minimising waste, contributing to sustainability goals. This paper contributes to emerging literature by analysing the development and comprehensive potential of reverse logistics as a sustainability tool. It explores the significant barriers to the adoption of reverse logistics towards a circular economy, considering long-term sustainability. In the first phase, thirteen barriers have been identified from the past academic literature. Three barriers with a defuzzification number less than the threshold limit are excluded, and the final ten barriers are then prioritised using the decision-making trial and evaluation laboratory (DEMATEL) method. The findings suggest that a lack of strategic plans for returns is crucial for RL adoption towards a circular economy, followed by a lack of visibility for recycling/reuse. Organisations can increase customer satisfaction, promote environmental sustainability, and gain a competitive edge in the market by creating a strategic plan for reverse logistics. Organisations may lower costs and contribute to a more sustainable and ecologically responsible supply chain by improving visibility across the reverse logistics process. The results serve as a framework for decision-making in RL towards sustainable development. Managers and policymakers can formulate more robust and realistic decisions that align with “maximising profits,” “saving the planet,” “social concerns,” and, most importantly, “consumer concerns” in the circular economy ecosystem. Several implications are derived, leading to increased competitiveness and resilient business strategies. The novelty of this work lies in the identification of barriers to reverse logistics adoption towards a circular economy using an integrated fuzzy Delphi-DEMATEL approach, considering long-term sustainability. This approach is studied for the first time in a developing economy context, proposing social, economic, and environmental effects and actions to be taken by organisations for sustainable development.Cleaner Logistics and Supply Chai
Rice stem lodging properties and bending modeling under the influence of circadian temperature difference
Get PDFUnder diurnal temperature stress, the vascular bundle content of mature rice stems will change which will cause a change in the modulus of elasticity. Therefore, the rice stems will collapse with the reduction in bending resistance because of the change in the modulus of elasticity. In order to reveal the distribution of vascular bundle gradients in rice stems under different climatic temperatures and explore the locations where stems are prone to bending and the form of stem damage, this study established a model of stem stiffness under free loading based on observing microstructure of the rice. The lodging characteristics of rice stems was explored seldom in different environmental temperatures from a micro structure of rice stems. So, the statistical analysis and t-tests were carried out on stems 1 to 4 in combination for cantilever bending tests at room temperature on stem internodes 3, versus three-point bending tests at –10°C to 65°C temperature treatment. Results showed that the bending resistance of the stem can be well predicted by using the vascular bundle distribution regression model and the variable stiffness mechanical model. The bending resistance of No. 3 stem was established by using the results obtained from the three-point bending test in a temperature range between 10°C-65°C. The correction coefficient TF of stem bending resistance under temperature difference induced stress was established based on the Gauss regression model. Statistical analysis showed that the bending resistance of No.3 stem was relatively large in a temperature range of 16°C-34°C. This study elucidated the variations of the mechanical properties of rice stems under temperature difference induced stress and provided a theoretical foundation for understanding the lodging characteristics of rice during mechanized harvesting.International Journal of Agricultural and Biological Engineerin
High performance rechargeable aluminium ion batteries enabled by full utilization and understanding of polyaniline cathodes
Get PDFAs a renowned conductive polymer, polyaniline (PANI) shows remarkable potential in organic cathode materials for rechargeable aluminium ion batteries (RAIBs). However, existing research has not given sufficient understanding and explanation of the structure and states of PANI but failed to achieve ideal electrochemical performance. In this study, we differentiate and investigate for the first time its primary-doped (PANI-1), re-doped (PANI-Re), secondary-doped (PANI-2), and emeraldine based (PANI-EB) forms, meanwhile attempt to enhance the conductivity of PANI-EB using multi-walled carbon nanotubes (PANI-EB@C). Among them, the high-doped PANI-2 and non-doped PANI-EB exhibit theoretical capacity utilization far superior to lower doped PANI-1 and PANI-Re, with both specific capacities reaching approximately 225 mAh/g (full capacity utilization rate of 76.53 %) at a current density of 1 A/g, while maintaining capacity retention rates of 92.89 % after 2000 cycles and 92.44 % after 5000 cycles, respectively. Furthermore, the high-conductivity PANI-EB@C displays a discharge specific capacity of 284 mAh/g (full capacity utilization rate of 96.59 %), with a capacity retention rate of 91.19 % after 5000 cycles. Electrochemical analysis, Gaussian theoretical calculations, ex-situ characterization collectively indicate that the electrochemical performance of doped PANI is positively correlated with the degree of doping-induced conductivity changes, while the unique internal redox process of PANI-EB enhances the release of performance and could be further optimized by the assistant of conductivity medium. This work advances the classification of the electrochemical performance and structural understanding of PANI cathode materials to an extremely high stage, towards the practical application of a low-cost, high-performance, sustainable, and green cathode material in large-scale energy storage devices.Chemical Engineering Journa
On the chemical composition, microstructure and mechanical properties of a Nitrogen-contaminated Ti-6Al-4V component built by Wire-Arc Additive Manufacturing
Get PDF44th Risø International Symposium on Materials Science (RISO 2024) 2-6 September 2024, Roskilde, DenmarkAdditive manufacturing (AM) using recycled Ti-6Al-4V (Ti64) feedstock material from wrought waste streams is a novel process that can reduce the overall energy cost and carbon (CO2) footprint when compared to primary-production routes. The potential contamination of recycled feedstock material (e.g. C, O, N and Fe) can affect the microstructure and mechanical properties of the component. In this work, a Ti64 test wall built using wire arc AM (WAAM) was studied, where the top half only was contaminated by N through the shielding gas during deposition. This allowed a direct comparison of Ti64 WAAM material with high and low N content, deposited under otherwise identical conditions, to replicate the worst-case scenario of N contamination from using recycled swarf. The hardness of the N-contaminated section was found to be 25% higher than the uncontaminated section of the wall, demonstrating the N solid solution strengthening in Ti64. The room temperature transformed microstructure was found to have a 25% coarser α-lath thickness, which was proposed to be an effect of the AM cyclical heating and increasing of the β-transus temperature due to a higher level of N. Additionally, the outer layer of the N-contaminated sample section was found to have a refined parent β grain structure.Engineering and Physical Sciences Research Council (EPSRC)The authors are appreciative of the EPSRC program grant Sustainable Additive Manufacturing (EP/W01906X/1) for supporting this research. The authors acknowledge the use of equipment within the Advanced Metals Processing and Characterisation themes of the Henry Royce Institute for Advanced Materials, funded through EPSRC grants EP/R00661X/1, EP/S019367/1, EP/P025021/1 and EP/P025498/1.44th Risø International Symposium on Materials Science (RISO 2024)IOP Conference Series: Materials Science and Engineerin