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dc.contributor.authorAlsalla, Hamza Hassn Ramadan
dc.date.accessioned2018-04-06T07:58:59Z
dc.date.issued2017-08-25
dc.description.abstractDirect Metal Laser Sintering (DMLS) and Selective Laser Melting (SLM) are an Additive Manufacturing (AM) technique that produces complex three- dimensional parts by adding layer upon layer of powder materials from bottom to top. Recently, AM has received a significant amount of press and is set to have an enormous impact such as decreasing the cost of production, fast and flexible, design freedom and increase the innovation opportunities. The powder base nature allows these techniques to process a variant of materials as well as produce complex composite parts and develop new materials system for Aerospace industries. The biggest problems in the process are limited surface quality and residual porosity in SLM and DMLS parts that are undesirable for some applications where fatigue resistance and high strength are essential. This research aims to improve the fracture toughness, ductility and fatigue of the metallic components, which is essential to be able to exploit the potential of the SLM and DMLS of these alloys for aerospace applications. In an additional development of the AM technology is not only limited to new machines but also processes, new materials, and methods, as it offers high mechanical properties and performance. This research focuses on DMLS and SLM of titanium and stainless steel alloys to investigate the effect of processes parameter and different build direction on toughness and fatigue crack growth property to change the physical and mechanical properties. Also, manipulate the process parameters and their effect on strength, fracture toughness and quality for both bulk and cellular lattice structure parts. The novelty in this study lies in using additive manufacturing process to evaluate the local failure mechanism of 316L bulk and cellular lattice structures made by SLM under uniaxial tension and three-point bending load. The effect of different build directions of the 316L lattice structure on the fracture toughness properties is compared to the Ashby and Gibson models. The findings demonstrate that the build direction does have an effect on the microstructure of parts, which subsequently has an effect upon mechanical properties and the surface quality of manufactured parts. Results found in this study will enable the designer to understand the important factors which affect the SLM and DMLS process and quality of final parts at different build direction. The comparison between micromechanics model and experimental results will help the designer to predict fracture toughness of AM cellular structures without the need of experimental tests. Finally, the results of mechanical properties of these bulk and lightweight parts will give a confidence to the designer to use and tailor their properties to specific applications.en_GB
dc.identifier.citationFracture toughness and tensile strength of 316L stainless steel cellular lattice structures manufactured using the selective laser melting techniqueen_GB
dc.identifier.citationEffect of build orientation on the surface quality, microstructure and mechanical properties of selective laser melting 316L stainless steelen_GB
dc.identifier.citationFatigue and fracture of high strength low alloy steel processed by additive manufacturingen_GB
dc.identifier.citationThe effect of different build orientation on the consolidation, tensile and fracture toughness properties of direct metal laser sintering Ti-6Al-4Ven_GB
dc.identifier.urihttp://hdl.handle.net/10871/32339
dc.language.isoenen_GB
dc.publisherUniversity of Exeteren_GB
dc.rights.embargoreasonI have placed an embargo on my thesis because I may attempt to get a few more papers published without my thesis being searchable on the web. I have published material from the work with a publisher that does not allow open access release for a certain period of timeen_GB
dc.titleEnhancing Fracture Toughness of Ultrahigh Strength Aerospace Components made by Additive Manufacturingen_GB
dc.typeThesis or dissertationen_GB
dc.contributor.advisorSmith, Christopher
dc.contributor.advisorEichhron, Steve
dc.publisher.departmentCollege of Engineering, Mathematics and Physical Sciencesen_GB
dc.type.degreetitlePhD in Engineeringen_GB
dc.type.qualificationlevelDoctoralen_GB
dc.type.qualificationnamePhDen_GB


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