Publication Date
2019
Document Type
Thesis
Committee Members
Joy Gockel, Ph.D. (Advisor); Onome Scott-Emuakpor, Ph.D. (Committee Member); Nathan Klingbeil, Ph.D. (Committee Member)
Degree Name
Master of Science in Mechanical Engineering (MSME)
Abstract
Additive manufacturing (AM) produces rough surfaces that are detrimental to the mechanical performance of the part. In this work, downward-facing surfaces were fabricated in alloy 718 using laser powder bed fusion and investigated with surface characterization and axial fatigue testing. Coupons with downward-facing surfaces at 45°, 60°, and 75° and flat axial fatigue bars with as-built and machined holes were built. Both specimens were fabricated with three levels of downskin laser power and the coupons with three levels of downskin laser speed. Surface characterization showed roughness increased as the downward-facing angle decreased. Fatigue testing with digital image correlation showed localized strain on the downskin as-built surfaces with deep notches and the fully machined specimens had ≥ 4 times longer life comparatively. Surface roughness is a critical factor in AM and this research gives insight to understand the influence of processing parameters and downward-facing angle on fatigue performance and build tolerances.
Page Count
140
Department or Program
Department of Mechanical and Materials Engineering
Year Degree Awarded
2019
Copyright
Copyright 2019, all rights reserved. My ETD will be available under the "Fair Use" terms of copyright law.
