Thesis
Fabrication with Laser-Powder Bed Fusion and characterisation of Zr702 lattices for an orthopaedic application
- Creator
- Rights statement
- Awarding institution
- University of Strathclyde
- Date of award
- 2024
- Thesis identifier
- T17130
- Person Identifier (Local)
- 201966018
- Qualification Level
- Qualification Name
- Department, School or Faculty
- Abstract
- Laser Powder Fed Fusion is an additive manufacturing technology that is industrially exploited for the production of orthopaedic implants exhibiting lattice features, that are open and geometrically ordered porous structures. In order to ensure the correct functioning of the prostheses, lattices must be made of biocompatible materials, they should exhibit adequate geometric accuracy and structural integrity, and their surface topography should promote (or at least not himder) the integration of the implant in the body (osteointegration). Nevertheless, the lack of standards and established methods for the measurement and characterisation of the lattices' geometrical accuracy and surface topography currently prevents the full assessment of such products, curtailing the confidence (thus, the market) over them. This research is devoted to the Laser Powder Fed Fusion manufacturing of octect lattices made in Zirconium (Zr702), a material that is often neglected in the biomedical research, although it offers excellent biocompatibility. The study is aimed, first, at optimising the additive manufacturing parameters for the printing of orthopaedic-relevant zirconium octet lattices. Second, it investigates the lattices fabricated with a set of optimal process parameters in a bio-mechanical perspective. Third, this work is aimed at developing methods that allow for the lattice's geometrical and topgraphical characterisation and that are relevant to orthopaedic implants. The study identifies a set of criteria that lattice structures should meet to ensure the "adequate geometrical accuracy and structural integrity" for an orthopaedic application. It shows the key process parameters and settings (laser power, scanning speed, printing strategy) that affect the geometrical accuracy and structural integrity of Laser Powder Based Fusion octet lattices, and provides several sets of manufacturing conditions that meet the above-mentioned criteria on geometry and structural integrity. This work assesses the quasi-static mechanical properties (particularly the stiffness) of optimised zirconium octet lattices, concluding that the fabricated lattices are relevant to orthopaedics and might be used to substitute compact bones. The biological assessment performed in this study investigates the behaviour of osteoblast-like cells on zirconium lattices and on full bulk disks, concluding that the material is deemed biocompatible, however lattice structures seem to be less biocompatible due to their surface topograpies. Chemical or electro-chemical surface treatments are recommended to smoothen the lattices' surface topography and maintain the material's biocompatibility. The study encompasses the measurement and characterization of the lattices' geometry, which was performed by X-rays Computed Tomography, image segmentation and analysis. A key output is the algorithm for the automatic geometrical characterisation of lattice struts and nodes (the key elements of lattice structures) along the different orientations of interest. Finally, the work entails the measurement and characterization of lattices' surface topography by Focus Variation Microscopy and the development of an algorithm that is relevant to orthopaedic lattice structures. A key output is the characterisation protocol that allows to detect and characterize the Partially Melted Particles, that are a common feature of surfaces generated by Laser Powder Bed Fusion.
- Advisor / supervisor
- Konʹkova, Tatʹi︠a︡na
- Butler, David Lee, 1962-
- Tamimi, Saeed
- Resource Type
- Note
- Previously held under moratorium from 8th October 2024 until 8th October 2026.
- DOI
Relations
Items
| Thumbnail | Title | Date Uploaded | Visibility | Actions |
|---|---|---|---|---|
|
|
PDF of thesis T17130 | 2025-01-15 | Public | Download |