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Characterization of steel components printed using WAAM technology
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Al-Nabulsi, Zeina (2021) Characterization of steel components printed using WAAM technology. PhD thesis, University of Warwick.
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Official URL: http://webcat.warwick.ac.uk/record=b385322
Abstract
This thesis presents the outcomes of research for structural engineering exploitation of 3D printed steel components produced by using Wire Arc Additive Manufacturing (WAAM) technologies. An objective of the research was to be able to apply WAAM with a Gas Metal Arc Welding (GMAW) based process to manufacture relatively large-scale components. The primary aim of the work was to study the printing process and printing strategy to produce several components for material and structural characterization work. To achieve this, several printing experiments were performed using several weld steels (in the form of 1.2 mm diameter wire), and with three external WAAM-GMAW collaborators. The largest component printed weighs 36 kg and is for a monolithic beam-to-column joint, having thin-walled beam and column sections of I-shape and different sizes. The smaller printed components (e.g., thin-walled plates and stub columns) were used to characterise the mechanical properties of the steels, which are benchmarked against Section 3 requirements in Eurocode 3 (EN 1993-1-1 or EN 1993-1-12) for the design of structural steel works. To investigate the internal structure and establish levels of porosity in the printed components, the non-destructive testing method of X-ray Computed Tomography (X-CT) analysis was employed.
From tensile coupon testing of the 3D printed steels the strains at rupture were assessed against the percentage of porosity formed during the 3D printing. A key finding was that for applications in buildings the presence of porosity has a small impact on the required material ductility and stiffness according to Eurocode 3. To satisfy the ductility requirement, the percentage of porosity should be controlled to be < 1%. Another important finding, from the X-CT evaluations, is that the printing process and its strategy both have a significant impact on the homogeneity and level of defects in the printed steels. The author therefore recommends that for quality printing it is important to consider the component’s load path and functionality during the design process leading to WAAM-GMAW manufacturing. Finally, testing of the beam-to-column joint for its moment-rotation characteristics showed that it can be classified by its stiffness to be ‘rigid’ (in accordance with Section 5.2 of EN 1993-1-8). This proved that the WAAM printed joint has the functionality of an equivalent conventional steel rigid joint for building structures.
The new data collected from this research forms the basis for the future development of design guidelines for using WAAM manufacturing technologies in structural engineering. Outcomes presented in this thesis can also be informative for the preparation of guidelines for safety factors, and for future applications on the potential impact on quality of steel printing of the chosen WAAM-GMAW parameters. Overall, the new contribution to knowledge and understanding is encouraging for there to be opportunities to apply 3D printing of steel to support the requirement of minimizing the mass of materials in structures for a zero-carbon economy.
Item Type: | Thesis (PhD) | ||||
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Subjects: | T Technology > TA Engineering (General). Civil engineering (General) T Technology > TN Mining engineering. Metallurgy T Technology > TS Manufactures |
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Library of Congress Subject Headings (LCSH): | Additive manufacturing, Three-dimensional printing, Three-dimensional printing -- Industrial applications, Steel, Steel wire | ||||
Official Date: | November 2021 | ||||
Dates: |
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Institution: | University of Warwick | ||||
Theses Department: | School of Engineering | ||||
Thesis Type: | PhD | ||||
Publication Status: | Unpublished | ||||
Supervisor(s)/Advisor: | Mottram, Toby | ||||
Format of File: | |||||
Extent: | xx, 190 leaves : illustrations, photographs | ||||
Language: | eng |
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