Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
Results
Showing 1 to 20 of 76 for “"NiTi"”.
-
Mechanical properties of superelastic and shape-memory NiTi and NiTi-TiC composites investigated by neutron diffraction
Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1999.
-
Degradation of NiTi springs through electronic actuation
… unique ability to recover its shape when heated. NiTi is a common SMA that is used mainly in orthodontic wires and light actuators such as on the NASA Pathfinder. However, when used in springs, the long-term reliability of these actuation forces has rarely been investigated. As SMAs are …
-
Variation of electrical resistance in superelastic NiTi for sensor applications
Nickel-Titanium (NiTi) is a most commonly known as a heat-activated shape memory alloy. However, the material sometimes displays a constant-temperature property called "superelasticity." A superelastic material is one which can undergo very high reversible strains due to stress-induced change in …
-
Tribological Investigation of Nickel Titanium Shape Memory Alloy (NiTi SMA) Coatings
Nickel titanium shape memory alloy (NiTi SMA) coatings demonstrate shape memory effects, superelasticity and excellent biocompatibility. It has been widely used in various applications such as in dentistry, orthopaedics and micro electro mechanical system. However, the application of NiTi SMA …
-
On the thermomechanics of localizing pseudoelastic transformations in NiTi materials and structures
Nearly equiatomic NiTi alloys undergo reversible solid-state transformations around room temperature, which are activated by the application of stress or by modest temperature changes. The forward transformation causes about 6% strain and the release of about 12 kJ/kg of latent heat; both are …
-
Atomistic to Continuum Multiscale and Multiphysics Simulation of NiTi Shape Memory Alloy
… and/ or stress (/strain). Among different SMAs, NiTi is a popular one. NiTi shows reversible phase transformation, the shape memory effect (SME), where irreversible deformations are recovered upon heating, and superelasticity (SE), where large strains imposed at high enough temperatures are fully …
-
Mechanical behavior and thermal recovery characterization of NiTi-TiC shape memory composites
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1994.
-
Mechanics of Phase Transformation in NiTi Shape Memory Alloys at The Atomistic Scale
… Alloys (SMAs), particularly Nickel-Titanium (NiTi) alloys, have received increasing attention mainly because of their promising role to be integrated into multifunctional systems for actuation, morphing, and sensory capabilities in a broad variety of applications including biomedical, …
-
The Development of Novel Apparatus, Systems, and Methods for Non-Invasive Thermal Interrogation (NITI)
Non-Invasive Thermal Interrogation (NITI) is a form of non-destructive testing (NDT) that uses simultaneous measurements of object surface heat flux and object surface temperature. When these measurements are combined with signal processing algorithms, such as parameter estimation routines or other …
-
Fully Covered,Retrievable Self-Expanding Metal Stent(Niti-S) in Palliation of Malignant Esophageal Obstruction
… who were treated with the fully covered Niti-S stent (Niti-S, Taewoong Medical, Seoul, Korea) were included. Data collected contained technical success rate of deployment and retrieval, dysphagia score changes, success rate of esophagorespiratory fistula (ERF) resolution, survival, stent …
-
The Effects of Applied Strain and Heat Treatment on the Properties of NiTi Wire During Shape Setting
NiTi components are commonly subjected to thermo-mechanical heat treatments during production and fabrication. This study investigates the effects of applied strain of 0-10% and heat treatments of 300-600ºC for times of 2-30 minutes during shape-setting of Ti–50.8 at% Ni wire with a nominal …
-
Diffraction Studies Of Deformation In Shape Memory Alloys And Selected Engineering Components
… to a twinning operation. In near equiatomic NiTi, Ti rich compositions can exist near room temperature as a monoclinic B19' martensitic phase, which when deformed undergoes twinning resulting in strains as large as 8%. Upon heating, the martensite transforms to a cubic B2 austenitic phase, …
-
The Effect of Stress State and Precipitation on Stress-Induced Martensitic Transformations in Polycrystalline and Single Crystal Shape Memory Alloys: Experiments and Micro-Mechanical Modeling
… stress-induced transformations in aged NiTi single crystals, a micro-mechanical model is used to quantify the stress fields outside perfectly coherent Ti$\sb{11}$Ni$\sb{14}$ precipitates in NiTi. Using the model, the decrease in the orientation dependence of $\sigma\sb{\rm cr}$ is linked …
-
Mesoscale Models for Stacking Faults, Deformation Twins and Martensitic Transformations: Linking Atomistics to Continuum
… energy pathway for B2→B19 transformation in NiTi. Based on our ab initio DFT calculations, we propose a combined distortion-shuffle pathway for B2→B19 transformation in NiTi. Our results indicate that in NiTi, a barrier of 0.48 mRyd/atom (relative to B2 phase) must be overcome to …
-
Nanoindentation of Annealed and As-Sputtered Thin Films of Nickel Titanium Shape Memory Alloys
… of interest for MEMS devices is nickel titanium (NiTi) shape memory alloy (SMA) because of the high work output (~107 J/m3). This thesis will focus on the fabrication of thin film NiTi by DC magnetron sputtering deposition and testing mechanical properties of the fabricated films by …
-
Effects of Topical Fluoride Prophylactic Agents on the Mechanical Properties of Orthodontic Nickel-Titanium Closed Coil Springs and Stainless Steel Closed Coil Springs
… unloading properties of nickel-titanium (NiTi) and stainless steel (SS) closed coil springs. Spring were stored at 37˚C under static load in phosphate buffered saline (PBS) and treated with either neutral sodium fluoride (NaF) or acidulated phosphate fluoride (APF) five days per week for …
-
Design, Fabrication, and Characterization of a Thin-Film Nickel-Titanium Shape Memory Alloy Diaphragm for Use in Micro-Electro-Mechanical Systems
… Poly has shown that thin-film nickel-titanium (NiTi) can be easily sputtered onto silicon wafers and annealed to create a crystallized shape memory alloy (SMA) film. Initial work on creating devices yielded cantilevers that were highly warped due to thin-film stress created during the sputtering …
-
Instrumented Nanoindentation Studies Of Deformation In Shape Memory Alloys
Near equi-atomic nickel titanium (NiTi) shape memory alloys (SMAs) are a class of materials characterized by their unique deformation behavior. In these alloys, deformation mechanisms such as mechanical twinning and stress induced phase transformation between a high symmetry phase (austenite) and a …
Page 1 of 4