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of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

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Author: Vasil Kavardzhikov

  • 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
    • Abstract
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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.

  • MATHEMATICAL MODELLING OF TECHNOLOGICAL PROCESSES AND SYSTEMS

    Modified Split Hopkinson Pressure Bar adapted to porous and low strength materials testing

    • Rumen Krastev
    • Vasil Kavardzhikov
    • Tatiana Simeonova
    Mathematical Modeling, Vol. 8 (2024), Issue 2, pg(s) 51-55
    • Abstract
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    A modified version of the Split Hopkinson-Kolsky Pressure Bar is described, intended for impact testing of porous metals and other low-strength materials. In it, one bar is made of aluminum alloy and the other bar is a steel tube. Several variants of the mathematical model for working with such devices are described. The stress-strain diagram of the specimen is extracted from the first impact signal. Attention has been paid to the approach to choosing the initial moments from which the calculations must start. Several examples are shown with solid and porous aluminum alloy samples. Despite the lack of high accuracy of the diagram at small stresses, the facility is suitable for quickly obtaining the overall appearance of the diagram after crushing small cylindrical specimens (up to 10 mm in diameter and height) and estimating the stresses at which the material deforms plastically.

  • 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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    04.-07.03.2024 - Borovets, Bulgaria
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