| The one of the objective of this thesis is to link the underlying microstructure of Ni-rich nickel titanium (NiTi) to the resulting fatigue properties. TEM, DSC and mechanical testing was used to characterize the base properties for the materials of this study. Two forms of deformation processing are examined with different aging treatments, which are sufficient to inducing both coherent and incoherent precipitation. The current method for determining fatigue response is to look at the austenitic ultimate tensile strength; however this is shown to give faulty impression of overall response.; An additional intention of this thesis is to introduce shape memory alloys (SMA) as an active implant material which could greatly advanced the medical industry. The most heavily utilized SMA in biomedical applications is NiTi due to its ability to instantaneously recover large amounts of deformation at a constant stress level. This paper describes the design of a new form of bone plate, utilizing the mechanical properties of NiTi. Also investigated is the biocompatibility of NiTi, demonstrating the potential of NiTi as a biomedical material. The results will be compared to the standard bone plate material, stainless steel (SS).; The final topic in the thesis will discuss the mechanics of three new tibial fixation devices. Tibial fixation of soft tissue grafts continues to be problematic in the early postoperative period after anterior cruciate ligament reconstruction. This has started an evolution of different device to overcome the weak point of tibial fixation, the device. The author will compare the mechanical properties of the new and old fixation devices with an in-vitro mechanical loading setup. (Abstract shortened by UMI.)... |
