Thesis
Processing and properties of porous metals; build direction dependant fatigue properties of lens(tm) made Ti6A14V; validity of simulated body fluid to ascertain biocompatibility of metals
Washington State University
Master of Science (MS), Washington State University
2018
Handle:
https://hdl.handle.net/2376/100502
Abstract
In load bearing orthopaedic implants, mostly metallic bio-materials such as titanium or titanium alloys are used, owing to their better mechanical properties. However, metallic implants tend to have much larger stiffness in comparison to the host bone tissue which might lead to stress shielding causing pain, inflammation or even loosening of the implant. Thus, a close match in the stiffness of the metallic implants with the surrounding bone tissue is necessary for the general longevity of implant. Also, the bio inert nature of metals enables them to form an encapsulating fibrous tissue rather than a strong interfacial bond with the surrounding tissue. Porous metallic structures have a two-fold advantage - ability to engineer the implant stiffness and also the facilitation of natural fixation for bone tissue ingrowth. Thus, a thorough overview of the literature on the fabrication processes and the physical, mechanical and biological properties of porous metallic structures for orthopaedic load-bearing applications has been conducted. Fatigue properties of the structures used as load bearing implants are critical and additive manufacturing becoming the fabrication process of choice, it is important to understand the influence of the processing decisions and parameters such as build direction and the scanning strategy on the fatigue property of the structure. Thus, in this study, LENS built fatigue samples, built with vertical and horizontal layering directions and different scanning strategies were tested for fatigue properties using rotational bending fatigue test setup and a significant change in the fatigue strength depending on the build direction was observed. Lastly, the validity of using the apatite growth on a material surface when soaked in simulated body fluid (SBF) to establish a material's biocompatibility has been assessed. From the results, it was observed that, while copper, a known cyto-toxic metal, when soaked in SBF showed extremely good deposition of apatite, while on the titanium surface without prior surface treatment in aqueous NaOH solution, very sparing nucleation of apatite on the surface occurred. Thus, the need for a better and more reliable standard to assess the acellular bio-compatibility of a material, in vitro, is realized.
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Details
- Title
- Processing and properties of porous metals; build direction dependant fatigue properties of lens(tm) made Ti6A14V; validity of simulated body fluid to ascertain biocompatibility of metals
- Creators
- Mahadev Upadhyayula
- Contributors
- Amit Bandyopadhyay (Degree Supervisor)
- Awarding Institution
- Washington State University
- Academic Unit
- Mechanical and Materials Engineering, School of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University; [Pullman, Washington] :
- Identifiers
- 99900525129801842
- Language
- English
- Resource Type
- Thesis