Browsing by Author "Lontin, Kevin"
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Item Open Access Interdependence of friction, wear, and noise: a review(Tsinghua University Press and Springer, 2021-04-19) Lontin, Kevin; Khan, MuhammadPhenomena of friction, wear and noise in mechanical contacts are particularly important in the field of tribomechanics but equally complex if one wants to represent their exact relationship with mathematical models. Efforts have been made to describe these phenomena with different approaches in past. These efforts have been compiled in different reviews but most of them treated friction, wear mechanics and acoustic noise separately. However, an in-depth review that provides a critically analysis on their interdependencies is still missing. In this review paper, the interdependencies of friction, wear and noise are analysed in the mechanical contacts at asperitical level. The origin of frictional noise, its dependencies on contact’s mechanical properties, and its performance under different wear conditions are critically reviewed. A discussion on the existing mathematical models of friction and wear is also provided in the last section that leads to uncover the gap in the existing literature. This review concludes that still a comprehensive analytical modelling approach is required to relate the interdependencies of friction, noise, and wear with mathematical expressionsItem Open Access Investigation of the effect of temperature on the wear rate and airborne noise in sliding wear(MDPI, 2022-01-21) Lontin, Kevin; Khan, Muhammad; Alharbi, BanderWhen friction processes occur, wear is generated. The generation of wear also leads to airborne noise. There have been many research studies on wear and its correlation with airborne noise, but most research has focused on experimental aspects, and theoretical models are rare. Furthermore, analytical models do not fully account for the wear and airborne noise generation, especially at an asperitical level. One model was developed that gave a reasonable quantification for the relationship between wear and airborne noise generation at an asperitical level under room temperature. In this paper, the accuracy of the model is assessed at higher temperatures. Two materials were set up on a tribometer (aluminium and iron) at 300 RPM. The samples were tested at two different temperatures (40 and 60 degrees) and two different loads were applied (10 N and 20 N). The model computed the predicted wear and sound pressure, and it was compared with the experimental results. The errors are larger for the wear than when the model was validated at room temperature. However, the increase in the error for the sound pressure was smaller at higher temperatures (approximately 20–30%). This is due to the assumptions that were made in the initial model, which are exacerbated when higher temperatures are applied. For example, flash temperatures were neglected in the original model. However, when initial heat is applied, the effects of flash temperatures could be more significant than when no heat is applied. Further refinements could improve the accuracy of the model to increase its validity in a wider temperature range.Item Open Access Wear and airborne noise interdependency at asperitical level: analytical modelling and experimental validation(MDPI, 2021-11-29) Lontin, Kevin; Khan, Muhammad A.Generation of wear and airborne sound is inevitable during friction processes. Previously, the relationship between the wear and the sound has only been determined experimentally. Analytical models do exist, but they remain rare and do not fully account for the wear and the airborne sound generation especially at the asperitical level. This model attempts to fill the gap by providing a quantifiable relationship at an asperitical level between the wear generated and the sound emitted in a simple pin-on-disc setup. The model was validated for three materials (iron, mild steel, and aluminium T351) under two loads (10 N and 20 N) at 300 RPM. The theoretical model agrees with the experimental results with a varying error of 10 to 15% error in iron and aluminium. However, a larger error is observed in the case of mild steel. The model could be refined to improve the accuracy as it assumes point impacts on the asperities where a distributed impact would be more suitable. Furthermore, the pin is assumed a single asperity to simplify the model at the expense of accuracy. Overall, the experimental results are in good correlation with the theoretical results and this model provides the first step in quantifying wear using only the recorded sound pressure.Item Open Access Wear and airborne noise interdependency at asperitical level: analytical modelling and experimental validation.(Cranfield University, 2021-09) Lontin, Kevin; Khan, Muhammad Ali; Starr, AndrewGeneration of wear and airborne sound is inevitable during friction processes. Most correlation between the wear and the sound generated during a sliding process have been experimental. Analytical models do exist, but they remain scarce and do not fully account for the wear and the airborne sound generation especially at asperitical level. The model developed in this research attempts to fill the gap by providing a quantifiable relationship between the wear generated and the sound emitted in a simple pin-on-disc setup. It provides a relationship between the wear and the sound from an asperitical level. This is done by examining the conditions at which wear would occur on an asperity distribution. The asperity distribution is considered to be exponential, although a Gaussian distribution was also considered. Impact forces are calculated on a per-asperity basis and the wear and vibrational displacement is calculated as a result. This leads to the quantification of wear and acoustic noise. The model is validated using a pin-on disc setup for three varied materials (iron (4% carbon content), mild steel (0.18% carbon content) and aluminium T351) under two loads (10 N and 20 N) at 300 RPM. The loads and speeds were chosen so as to observe a range of wear behaviour while remaining within the constraints of the lab limitations and the safety of the force sensors on the tribometer. Temperatures are also examined, and a second set of validation experiment is performed at temperatures of 40 °C and 60 °C. The model computes the predicted wear and sound pressure, and it is compared with the experimental sound pressure measured by the microphone and the wear measured by the tribometer sensors. Sound pressure is chosen as a measure over frequency because it is easier to analyse and compare. The theoretical model agrees with the experimental results with a varying error of 10 to 15 % error in iron and aluminium. However, a larger error is observed in the case of mild steel. The model could be refined to improve the accuracy as it assumes point impacts on the asperities where a distributed impact would be more suitable. Furthermore, the pin is assumed a single asperity to simplify the model at the expense of accuracy. Overall, the experimental results are in fair correlation with the theoretical results and this model provides the first step in quantifying wear using only the recorded sound pressure.