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Author: Georgi Stoilov

  • MATERIALS

    Influence of Al2O3 content on the mechanical properties of sintered Al-10Cu-xAl2O3 composites

    • Tatiana Simeonova
    • Rumen Krastev
    • Georgi Stoilov
    • Vasil Kavardzhikov
    Machines. Technologies. Materials., Vol. 19 (2025), Issue 2, pg(s) 75-78
    • Abstract
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    This study investigates the influence of Al₂ O₃ content on the mechanical properties of sintered Al-10Cu-xAl₂ O₃ (x = 2.5, 5, and 7.5 wt.%) composite materials, produced via powder metallurgy and subjected to quasi-static and dynamic compressive loadings. Quasistatic tests were performed at a constant strain rate of 0.003 s⁻ ¹, while dynamic tests were conducted at strain rates corresponding to impact velocities of approximately 10 m/s and 20 m/s. The results indicate that a higher Al₂ O₃ content enhances the mechanical properties of the composite under both quasi-static and dynamic compression. The most significant improvements were observed under high strain rate impact loading, highlighting the potential of sintered Al-10Cu-xAl₂ O₃ for applications in dynamic environments.

  • DOMINANT TECHNOLOGIES IN “INDUSTRY 4.0”

    Mechanical characterisation of Babbitt Alloys solidified under different conditions

    • Tatiana Simeonova
    • Rumen Krastev
    • Georgi Stoilov
    • Vasil Kavardzhikov
    Industry 4.0, Vol. 10 (2025), Issue 2, pg(s) 64-67
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    This paper investigates the mechanical behaviour of SnSb11Cu6 Babbitt alloys solidified under pressure and under atmospheric conditions. Quasi-static tests were performed at three different constant strain rates: 0.001 s⁻ ¹, 0.003 s⁻ ¹, and 0.01 s⁻ ¹, while dynamic tests were conducted at strain rates corresponding to impact speeds of 10 m/s and 20 m/s. The results indicate that alloys solidified under atmospheric conditions exhibit higher compressive strength in the quasi-static regime than those solidified under pressure. However, as the impact speed increases to 1400 s-1 the compressive strength of both materials converges. Beyond this rate (up to 2800 s⁻ ¹), the alloy solidified under pressure shows a slight performance shift, suggesting better property stability at higher loading rates. Overall, the alloy solidified under atmospheric conditions offers superior performance for low-strain applications, whereas the alloy solidified under pressure demonstrates more stable properties under high-strain loadings. These findings offer valuable insights for the selection and design of materials in tribological systems, particularly where performance varies under different loading conditions.

  • DOMINANT TECHNOLOGIES IN “INDUSTRY 4.0”

    Mechanical Characterization of Al-Cu Materials Fabricated by Powder Metallurgy under Quasi-static and Dynamic Compressive Loadings

    • Tatiana Simeonova
    • Rumen Krastev
    • Georgi Stoilov
    • Vasil Kavardzhikov
    Industry 4.0, Vol. 9 (2024), Issue 5, pg(s) 182-185
    • Abstract
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    This study investigates the mechanical behaviour of Al10Cu materials fabricated through powder metallurgy and subjected to quasi-static and dynamic compressive loadings. The materials were sintered and tested under controlled conditions to evaluate their compressive strength. Quasi-static tests were performed at a constant strain rate of 0.003 s⁻ ¹, while dynamic tests were conducted at strain rates corresponding to impact speeds of about 10 m/s and 20 m/s. The results indicate that sintered Al10Cu materials are suitable for applications under high-strain impact loadings due to their high energy absorption. These findings highlight the potential of powdermetallurgy-derived Al10Cu alloys for applications requiring high strain rate performance, offering insight into their suitability for use in dynamic environments.

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