Project Title: “Experimental Investigation on the Influence of Surface Defects on High-Speed Gear Performance”
Advisor: Dr. Ahmet Kahraman, Mechanical and Aerospace Engineering
Co-Advisor: Dr. Michael Handschuh, Mechanical and Aerospace Engineering
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Link to Video Presenation:
Poster PDF:
Experimental Investigation on the Influence of Surface Defects on High Speed Gear Performance
Abstract:
Gear tooth surfaces may contain undesirable defects for various reasons. One group of defects are caused by the initial circulation of debris contained within a gearbox such as casting sand and machining debris. Such debris could cause dents and short scratches on tooth surfaces if they mix with the lubricant in the early stages of operation and find their way to the gear contact interface, initiating damage before being removed through filtration. The second group consists of manufacturing and assembly related defects, typically in the form of scratches. While the effects of debris-induced defects are known, durability consequences of scratches are yet to be investigated. In this study, singular calibrated scratches varying in location and orientation were applied to tooth surfaces of three otherwise high-quality, aerospace grade spur gears. These gears, along with an undamaged control gear pair, were put through staged scuffing experiments that incrementally increased torque, operating speed, and bulk lubricant temperature at aerospace operating conditions. Gear coordinate measurements were performed initially to verify scratch location and that gear geometries and microgeometries were within the specifications. Throughout testing, nondestructive metrology techniques involving microscope imaging and probe roughness traces were used at various sites along the scratch to track scratch-induced surface damage and changes in scratch geometry. All three gear pairs with scratched pinions failed prematurely from scuffing at less severe operating conditions compared to the control gear.