Browsing by Author "Karadimas, Georgios"

Now showing 1 - 5 of 5
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    Degradation and fatigue life methods for ceramic matrix composite and nickel superalloy materials in gas turbine combustor liner
    (Springer Nature, 2024-12-08) Karadimas, Georgios; Pagone, Emanuele; Georgarakis, Konstantinos; Salonitis, Konstantinos
    This paper investigates the durability of Ceramic Matrix Composite (CMC) and Nickel Superalloy materials in gas turbine combustor liners across different flight conditions. Thermo-mechanical and physical properties of CMCs are assessed and compared with selected superalloys (i.e., Inconel 625, Hastelloy X, SiC/SiC, Al2O3/B4C, and Al2O3/SiO2) using Finite Element Analysis (FEA). An integrated methodology employing Computational Fluid Dynamics (CFD) and FEA is introduced to analyze thermal stresses and fatigue life, establishing a direct connection between combustion dynamics and structural responses. The study addresses a research gap by thoroughly evaluating CMC materials in gas turbine combustor liners, offering valuable insights for material selection and design strategies in aerospace engineering. The findings enhance understanding of CMC behavior, showcasing their reliability and durability for gas turbine components and their usage for advancements in aerospace applications.
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    Environmental impact assessment of manufacturing of SiC/SiC composites
    (Springer Nature, 2025-01-07) Karadimas, Georgios; Yuksek, Yagmur Atescan; Salonitis, Konstantinos
    SiC/SiC composites have attracted increasing attention in various applications such as turbine blades, exhaust nozzles, and combustor chambers, due to their exceptional mechanical and thermal properties. However, the environmental impact of these composites across their life cycle is an important aspect that needs to be evaluated to support their responsible development and use. In this study, a life cycle assessment of SiC/SiC woven laminate ceramic matrix composites to quantify their environmental impacts from cradle-to-gate was conducted. Three different manufacturing methods to produce SiC/SiC woven laminates were researched: chemical vapour infiltration (CVI), pyrolysis of a preceramic polymer (PIP), and melt infiltration (MI). The Life Cycle Assessment approach was utilized to identify the effect outcomes for each process, analysing the raw material extraction, raw material processing, and final product manufacturing phases to develop the environmental impact assessment. The study's outcome showed that CVI had the lowest average environmental impact between the two methods.
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    Environmental impact assessment of titanium swarf cleaning methods
    (KES International, 2024-09-20) Karadimas, Georgios; Pagone, Emanuele; Salonitis, Konstantinos; Jolly, Mark R.; Williams, Stewart
    This paper evaluates the environmental impacts of chemical based and CryoClean swarf cleaning techniques through a comprehensive Life Cycle Assessment (LCA) aimed at identifying sustainable practices for recycling titanium swarf in additive manufacturing processes. Employing ISO 14040 and 14044 standards, the study focuses on a functional unit of cleaning 100 gr of titanium swarf, enabling direct comparison of environmental footprints across these methods. Data for the inventory analysis includes specific inputs such as energy consumption, water use, and chemicals, alongside outputs like emissions and waste generation, with supplemental secondary data sourced from Ecoinvent. The impact assessment utilizes the ReCiPe methodology, concentrating on key environmental indicators such as Global Warming Potential (GWP) and Acidification Potential (AP). The findings reveal distinct environmental trade-offs between the chemical based and CryoClean methods. Chemical-based cleaning, while effective at removing contaminants, often involves the use of hazardous substances that can lead to significant ecological impacts. In contrast, CryoClean, which utilizes liquid nitrogen to freeze and remove impurities, shows a lower environmental impact across several categories but may require higher energy inputs. By estimating the specific environmental impacts of the selected swarf cleaning techniques, the study contributes valuable insights towards optimizing material recovery and advancing circular economy principles in industrial manufacturing. The paper aims to guide industry stakeholders toward adopting more environmentally sustainable practices that align with the transition to greener manufacturing processes.
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    Literature review of fatigue life performance of ceramic materials
    (IOS Press, 2022-09-08) Karadimas, Georgios; Salonitis, Konstantinos
    Ceramic materials are widely used nowadays in the aerospace sector. However, functional ceramics have not yet been fully researched in terms of their life expectancy under all possible loading scenarios. Ceramics have low toughness and high brittleness, but great thermal properties as it has been widely documented in the literature. A lack of research however with regards to ceramic material life expectancy models is evident. The fatigue life of ceramic materials is not thoroughly researched and there is a need for comparing them with more traditional materials used for similar purpose applications. In the present paper, the fatigue performance of several ceramic materials will be analyzed by using S-N curves, simulating the cumulative damage caused to these materials by different constant amplitude stresses applied from a wide range of applications and more specifically, aero-engine applications. Finally, the already existing literature on ceramic failure mechanisms and models will be evaluated and compared with the simulated life expectancy models to identify improvement opportunities and a guide for developing and deploying these materials to the extended use of applications.
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    Techno-Economic analysis of ceramic matrix composites integration in remaining useful Life Aircraft Engine Hot Section Components
    (Springer, 2024-12-01) Karadimas, Georgios; Ioannou, Anastasia; Kolios, Athanasios; Salonitis, Konstantinos
    Ceramic Matrix Composites (CMCs), specifically SiC/SiC composites, represent a significant innovation in aerospace material technology, offering superior performance over traditional nickel-based superalloys in high-temperature turbine blade applications. This study presents a novel techno-economic assessment, filling a critical gap in the literature by directly comparing the economic and technical viability of CMCs versus superalloys. Unlike previous studies, which primarily focus on technical performance or cost analysis independently, this work integrates both aspects, providing a holistic comparison across key economic metrics, including acquisition, machining, maintenance, and recycling costs. The results demonstrate that SiC/SiC blades offer a 15–20% higher Net Present Value (NPV) and a 17% greater Internal Rate of Return (IRR) over a 20-year lifecycle than superalloys. Despite higher initial costs, CMCs achieve an estimated 2 to 3 years reduction in payback period, mainly due to their superior thermal and creep resistance, leading to fewer maintenance interventions and longer operational lifetimes. Although machining costs for CMCs are higher, these are more than offset by the long-term savings achieved through improved fuel efficiency and lower maintenance costs. A comprehensive sensitivity analysis, incorporating fluctuations in discount rates and material costs, further validates the economic robustness of CMCs in various operational scenarios. This study is the first to compare CMCs and superalloys, offering new insights into the financial implications of material selection in aerospace manufacturing. The findings present critical engineering recommendations that empower aerospace manufacturers and decision-makers to optimise material selection for improved efficiency and cost-effectiveness in high-performance turbine applications.