Browsing by Subject "fatigue performance"
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Item Comparison of Fatigue Performance Between Additively Manufactured and Wrought 304L Stainless Steel Using a Novel Fatigue Test Setup(University of Texas at Austin, 2019) Parvez, M.M.; Chen, Y.; Newkirk, J.W.; Liou, F.F.In this research, a novel adaptive controlled fatigue testing machine was designed for bending type high cycle fatigue test. A unique dual gauge section Krouse type mini specimen was designed for simply supported transverse bending. Displacement controlled fatigue tests were implemented using an electromechanical actuator. The variation in the control signal and load observed during the test provides unique insights into realizing the deterioration of the specimen due to fatigue. These analyses were utilized to compare the fatigue performance of wrought and additively manufactured 304L stainless steel. The influence of the build direction on fatigue performance was also investigated by testing specimens with 0, 45, and 90 degrees build direction. These comparisons were carried out at different levels of displacement amplitude.Item Effect of Defects on Fatigue Tests of As-Build Ti-6Al-4V Parts Fabricated by Selective Laser Melting(University of Texas at Austin, 2012-08-16) Gong, Haijun; Rafi, Khalid; Starr, Thomas; Stucker, BrentDefects can be found in parts made using Selective Laser Melting (SLM) due to balling effects and other types of localized irregularities. This study investigates how defects affect the fatigue performance of Ti-6Al-4V samples in an SLM as-built surface finish condition. Fatigue samples were built and heat treated for stress relief. In order to investigate the effect of defects, a series of fatigue samples were designed with built-in cylindrical and double-conical defects. Tests were carried out to correlate maximum stress to the number of cycles to failure. Optical and scanning electron micrographs were utilized to compare and analyze crack initiation and propagation characteristics. Based on the results, the influence of defects on fatigue properties is discussed.Item Electrochemical Enhancement of the Surface Morphology and the Fatigue Performance of Ti-6Al-4V Parts Manufactured by Laser Beam Melting(University of Texas at Austin, 2017) Bagehorn, S.; Wehr, J.; Nixon, S.; Balastrier, A.; Mertens, T.; Maier, H.J.In the course of the industrialization of the Additive Manufacturing (AM) process of metallic components, the surface finish of the final parts is a key milestone. ‘As-built’ AM surfaces feature a high initial surface roughness (i.e. Ra > 10 µm), which often exceeds the specification for technical applications. In order to apply AM for highly stressed and cyclically loaded components, the as-built surface roughness needs to be reduced. Since conventional surface finishing processes as machining or blasting often show a limited applicability to complex shaped AM parts, an enhanced electrolytic polishing process was developed (3D SurFin®). Within the present study, Ti-6Al-4V AM plates and fatigue samples were produced in a powder bed laser beam system. The enhanced electrolytic polishing process led to a significant roughness decrease of approximately 84 % for a treatment time of 60 min. Also, a notable improvement of the fatigue performance of 174 % was achieved after a treatment time of 40 min in comparison to the as-built reference samples.Item Fatigue Performance Enhancement of Selectively Laser Melted Aluminum Alloy by Heat Treatment(University of Texas at Austin, 2015) Maskery, I.; Aboulkhair, N.T.; Tuck, C.; Wildman, R.D.; Ashcroft, I.A.; Everitt, N.M.; Hague, R.J.M.We measured the stress-strain behaviour and fatigue performance of the aluminium alloy Al-Si10-Mg manufactured by selective laser melting (SLM). This process, specifically the rapid cooling of the metal from its molten state, results in a fine microstructure, generally providing high hardness but poor ductility. We used a heat treatment to alter the microstructure of the material from its as-built state. This significantly improved the ductility and fatigue performance. The elongation at break for the heat treated material was nearly three times greater than that observed for the as-built material, and the fatigue strength at 106 cycles was around 1.6 times as high. Combined with the design freedoms of additive manufacture, this development increases the suitability of lightweight SLM parts for use in the aerospace and automotive sectors, where good fatigue performance is essential.