Browsing by Author "Kalifa, Mohamed"

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    Analyzing frictional noise for wear monitoring under dry and lubrication condition: experimental modelling with pin-on-disc tribometer
    (Trans Tech Publications Ltd, 2025-01-06) Kalifa, Mohamed; Starr, Andrew; Khan, Muhammad
    In industrial settings, the use of frictional noise to improve wear monitoring is highly promising. It enables the identification of changes in friction and wear conditions, the assessment of different phases of wear, and the examination of the impact of wear on machine performance. By analysing acoustic signatures, it is conceivable to continuously monitor the wear characteristics and surface conditions. This helps in predicting wear and detecting aberrant wear regimes in real-time. The data demonstrate that in dry conditions, the aluminum disc has higher coefficients of friction relative to cast iron and mild steel, likely due to the absence of graphite flakes in aluminum. Under lubricated conditions, a layer of lube significantly decreases the coefficient of friction, with no apparent deviations across the materials, demonstrating that complete lubrication avoids direct metal contact. In lubrication-starved applications, oily depictions nevertheless help minimize friction, though less efficiently than complete lubrication. In dry conditions, frictional sound levels for mild steel are higher due to direct surface hits, while lubrication reduces noise by eliminating metal-on-metal contact. As a result, monitoring noise levels is a helpful indicator of lubrication difficulties, aiding in maintenance and repairs.
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    Interplay between wear and thermal expansion in 6082 aluminum: a simulation and experimental study
    (MDPI, 2024-11-23) Tian, Yang; Kalifa, Mohamed; Khan, Muhammad; Yang, Yifan
    This study investigates how wear and thermal expansion interact in 6082 aluminum, utilizing a pin-on-disc tribometer and finite element analysis under diverse mechanical conditions. The findings show that thermal expansion reduces contact area by forming a protrusion at the contact interface. This interaction between wear and thermal expansion causes dynamic shifts in the contact region and pressure distribution, affecting the disc center and altering wear progression and temperature patterns. High thermal expansion shifts maximum wear from the contact center to outer regions, especially at higher speeds and loads. Without thermal expansion, wear-only conditions overestimate friction dissipation, resulting in a higher peak temperature. These results highlight the critical role of thermal expansion in shaping wear patterns and contact behavior in sliding applications. This research offers insights for optimizing tribological performance in 6082 aluminum, with potential applications in other materials.