Faculty of Mechanical Engineering

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Author: search.filters.author.Stankoski, Marko

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    Effect of laser beam and arc power on weld bead geometry in hybrid laser arc welding of structural steel
    (Centre for Evaluation in Education and Science (CEON/CEES), 2024)
    Petreski, Martin
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    Vrtanoski, Gligorche
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    Stankoski, Marko
    <jats:p>Hybrid Laser Arc Welding - HLAW combines the advantages of Laser Beam Welding - LBW and Gas Metal Arc Welding - GMAW, resulting in a welding process of high welding speed, less heat input, deeper penetration into the welding material, and increased process efficiency compared to conventional welding processes. The merger of the two heat sources, laser beam and arc, in a single welding process leads to a weld joint characterized by two zones, an upper-wide zone or laser-arc zone and a lower narrow zone or laser zone. This study investigates the impact of laser beam and arc currents on the weld bead geometry in the arcleading hybrid laser arc welding process of 12 (mm) structural steel. Through systematic experimentation, single-pass hybrid laser arc welds were performed in a butt joint configuration with zero-gap at various power settings, laser beam power range 10 - 13 (kW), and arc current range 340 - 400 (A) to determine their influence on weld bead width, height, and depth. The quality level of the hybrid laser arc welds was evaluated according to ISO 12932. The results indicate that increasing laser beam power enhances weld bead depth and narrows bead width, while the arc current is directly related to weld bead height and overall smoothness. The findings show that weld bead geometry is a function of laser beam and arc power ratio, an increased ratio leads to a narrow weld bead and vice versa.</jats:p>
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    Effect of laser beam and arc power on weld bead geometry in Hybrid Laser Arc Welding of structural steel
    (Serbian Welding Society, 2024)
    Petrevski, Martin
    ;
    ;
    Vrtanoski, Gligorche
    ;
    ;
    Stankoski, Marko
    Hybrid Laser Arc Welding – HLAW combines the advantages of Laser Beam Welding - LBW and Gas Metal Arc Welding - GMAW, resulting in a welding process of high welding speed, less heat input, deeper penetration into the welding material, and increased process efficiency compared to conventional welding processes. The merger of the two heat sources, laser beam and arc, in a single welding process leads to a weld joint characterized by two zones, an upper-wide zone or laser-arc zone and a lower narrow zone or laser zone. This study investigates the impact of laser beam and arc currents on the weld bead geometry in the arcleading hybrid laser arc welding process of 12 (mm) structural steel. Through systematic experimentation, single-pass hybrid laser arc welds were performed in a butt joint configuration with zero-gap at various power settings, laser beam power range 10 - 13 (kW), and arc current range 340 - 400 (A) to determine their influence on weld bead width, height, and depth. The quality level of the hybrid laser arc welds was evaluated according to ISO 12932.
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    Design and Analysis of a Modular VTOL Drone With Bat-Inspired Wings
    (American Society of Mechanical Engineers, 2020-09-15)
    Anachkova, Maja
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    Stankoski, Marko
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    Berberu, Mihael
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    Atanasov, Aleksandar
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    Janevski, Jane
    <jats:title>Abstract</jats:title> <jats:p>The future of technology lies in the diverse characteristics and capabilities of autonomous machines and devices and their application in many technical challenge. Rapid technology development, market globalization and availability of affordable electronics and controllers, have recently resulted in increased scientific and technical interest in drones as autonomous solutions for professional, as well as, amateur applications. On the other hand, researchers have been improving how manmade machines move through air by attempting to replicate animals motion by mimicking their aerial abilities.</jats:p> <jats:p>In this paper, we propose a development of a bio-inspired modular drone concept motivated by the bats agility, wingspan and wings folding into various shapes. The drone can be tailored for different applications, from sea port mapping, surveying, tank inspection and port traffic control to pollution monitoring and detection of illegal activities. The aerial performances of the drone allow it to be able to conduct windmills monitoring by connecting to their local monitoring units and send alerts to officials in real-time. This small bat-inspired drone is proposed to have an ability of performing flights with precisely defined trajectories. The accent will be put on the interchangeable wings, analysis of their dynamic attributes and transformation possibilities as a crucial segment of the overall drone performance. The design and fabrication process and the flight characteristics of the various wing configurations of the drone are discussed in details. Limitations of the drone, proposed solutions for further development and recommendations are also presented.</jats:p>