/library/oar/handle/123456789/519 The Faculty of Engineering is located at the University's main campus and offers tuition and supervision to about 477 students at both undergraduate and postgraduate levels while conducting research in all fields covered by its departments. 2025-12-27T12:13:53Z /library/oar/handle/123456789/142440 Title: Design optimization of a starter generator for more sustainable high power density aerospace applications Authors: Devito, Giampaolo; Theofanous, Antonis; Barater, Davide; Nuzzo, Stefano Abstract: The surface-mounted permanent magnet synchronous motor has found widespread use across various sectors, owing to its outstanding characteristics of torque density, efficiency and ease of control. These features, particularly crucial in the aviation field, make this type of machine highly desirable, especially in fixed-speed applications such as single-speed starter-generators. Additional performance metrics usually required nowadays in transportation are the sustainability and the overall environmental impact of components and systems. In this context, this paper proposes the design of a surface-mounted permanent magnet synchronous motor for a fixed-speed starter-generator, emphasizing all these different performance requirements. The design process is based on finite element (FE) optimizations, achieving a number of possible optimal configurations from an electromagnetic point of view, but giving then priority to the most environmentally friendly solutions. The outputs under examination are efficiency, power density, total harmonic distortion, torque ripple, copper and permanent magnet quantities, and temperatures. A motor characterized by a power density exceeding 2,3 kW/kg, 98% efficiency, and reduced copper and permanent magnet content is obtained. 2024-11-01T00:00:00Z /library/oar/handle/123456789/142211 Title: Enhancing fatigue resistance in WAAM AZ80 magnesium and wrought Al6082 through shot peening : a comparative study Authors: Grima, Daniel; Layeb, Nejmeddine; Li, Runsheng; Zammit, Brian; Attard, Bonnie; Zammit, Ann; Cassar, Glenn Abstract: Shot peening is a well-established surface treatment that enhances mechanical performance by inducing plastic deformation, grain refinement and compressive residual stresses. This study evaluates the effects of shot peening on wire arc additively manufactured (WAAM) AZ80 magnesium alloy, benchmarked against wrought Al6082 aluminium—a widely used aerospace material. WAAM AZ80 was assessed in two states: a baseline variant (P1) with significant retained process-induced defects, and an improved version (P2) produced via refined processing parameters. Microstructure, hardness, surface roughness, residual stress and fatigue behaviour were systematically analysed. Shot peening induced notable grain refinement in both materials without causing phase transformations. Surface hardness increased by 18% in Al6082, and by 37% and 45% in WAAM AZ80 (P1 and P2, respectively), mainly due to work hardening and grain boundary strengthening. Increased surface roughness was observed across all conditions. Al6082 exhibited peak compressive residual stresses of ~280 MPa at depths >100 µm, whilst WAAM AZ80 reached ~ 110 MPa at ~ 75 µm. Fatigue life improved by 44% in Al6082, and by 100–350% depending on the orientation of residual defects caused by the AM process in the WAAM AZ80 (P1) specimens. Shot peening proved effective in mitigating the influence of surface and near-surface defects. Densified WAAM AZ80 (P2) samples also exhibited significantly improved fatigue performance after shot peening, reaching the test run-out of 106 cycles without failure. The improvements in WAAM AZ80 are largely attributed to reduced surface-connected porosity and delayed crack initiation. Whilst Al6082 retains superior fatigue properties, shot-peened WAAM AZ80 shows strong potential as a lightweight alternative for weight-sensitive aerospace applications involving cyclic loading. 2025-01-01T00:00:00Z /library/oar/handle/123456789/142086 Title: Pore-size-dependent mechanical properties and biodegradation behavior of biomedical Zn-Li alloy scaffolds Authors: Xin, Jie; Li, Qiang; Wang, Cheng; Chu, Chenglin; Xue, Feng; Yang, Youwen; Giordmaina, Ryan; Buhagiar, Joseph P.; Dong, Qiangsheng; Bai, Jing Abstract: Zn-Li alloys have emerged as promising candidates for bone repair applications due to their excellent mechanical properties and osteogenic potential. In this study, porous Zn-0.7Li scaffolds were fabricated via infiltration casting, with adjustable spherical pore sizes to achieve high porosity and thin-walled structures. Increasing pore size from 550 μm to 950 μm was accompanied by a corresponding elevation in scaffold porosity from 65.6 % to 71.2 % and a concurrent increase in the average wall thickness from 0.21 mm to 0.31 mm. Herein, the compressive yield strength decreased exponentially with rising porosity, while the degradation weight loss rate correlated linearly with specific surface area. The compressive yield strength of Zn-Li scaffolds were enhanced by solid solution strengthening and β-LiZn4 phase on the Zn matrix, superior to Zn-Mg alloy and pure Zn scaffolds at equivalent porosity. Besides, Zn-0.7Li scaffolds showed accelerated degradation due to their larger specific surface area. Based on the evolution of pore structure and mechanical properties during degradation, a mechanical performance decay model was established, which predicted the mechanical half-life of the Zn-0.7Li scaffolds as 61–122 days. This study provides insights into the quantitative relationship between pore structure and physicochemical properties of biodegradable bone repair materials, exploring feasible technical routes for developing high-performance scaffolds. 2025-01-01T00:00:00Z /library/oar/handle/123456789/141945 Title: A comprehensive review of solar PV Integration with smart-grids : challenges, standards, and grid codes Authors: Rajendran, Gowthamraj; Raute, Reiko; Caruana, Cedric Abstract: Promoting a sustainable and low-carbon energy future through the integration of renewable energy is essential, yet it presents significant challenges due to the intermittent nature of resources such as solar and wind. This paper examines the technological and economic dimensions of AC, DC, and smart grids, concentrating on the optimization of costs, efficiency, stability, and scalability. Smart grids, enhanced by AI, IoT, and blockchain technologies, play a vital role in energy management optimization, predictive maintenance, and secure energy transactions. Furthermore, the incorporation of renewable energy sources, especially photovoltaics, presents challenges including intermittency, voltage fluctuations, and grid congestion. This paper emphasizes the necessity for updated grid codes and policies that guarantee system stability and the effective functioning of renewable energy systems. The implementation of these regulatory frameworks is crucial for facilitating the efficient integration of renewable energy into the grid, ensuring a reliable and secure power supply while advancing sustainability efforts. 2025-01-01T00:00:00Z