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Thermo-Mechanical Characterization Of High-Temperature Shape Memory Ni-Ti-Pd Wires, Matthew Fox
Thermo-Mechanical Characterization Of High-Temperature Shape Memory Ni-Ti-Pd Wires, Matthew Fox
Electronic Theses and Dissertations
Actuator applications of shape memory alloys have typically been limited by their phase transformation temperatures to around 100 degrees C. However, recently with a focus on aerospace and turbomachinery applications there have been successful efforts to increase the phase transformation temperatures. Several of these alloy development efforts have involved ternary and quaternary elemental additions (e.g., Pt, Pd, etc.) to binary NiTi alloys. Experimentally assessing the effects of varying composition and thermo-mechanical processing parameters can be cost intensive, especially when expensive, high-purity elemental additions are involved. Thus, in order to save on development costs there is value in establishing a methodology …
Design, Fabrication And Testing Of A Low Temperature Heat Pipe Thermal Switch With Shape Memory Helical Actuators, Othmane Benafan
Design, Fabrication And Testing Of A Low Temperature Heat Pipe Thermal Switch With Shape Memory Helical Actuators, Othmane Benafan
Electronic Theses and Dissertations
This work reports on the design, fabrication and testing of a thermal switch wherein the open and closed states are actuated by shape memory alloy elements while heat is transferred by a heat-pipe. The motivation for such a switch comes from NASA's need for thermal management in advanced spaceport applications associated with future lunar and Mars missions. For example, as the temperature can approximately vary between 40 K to 400 K during lunar day/night cycles, such a switch can reject heat from a cryogen tank in to space during the night cycle while providing thermal isolation during the day cycle. …
Low Temperature And Reduced Length Scale Behavior Of Shape Memory And Superelastic Niti And Nitife Alloys, Radhakrishnan Manjeri
Low Temperature And Reduced Length Scale Behavior Of Shape Memory And Superelastic Niti And Nitife Alloys, Radhakrishnan Manjeri
Electronic Theses and Dissertations
Shape memory and superelastic applications of NiTi based alloys have typically been limited to near room temperature or to bulk length scales. The objective of this work is two-fold: first, to investigate shape memory behavior at low temperatures in the context of the R-phase transformation in NiTiFe alloys by recourse to arc-melting, differential scanning calorimetry (DSC), transmission electron microscopy (TEM) and mechanical testing at low temperatures; and second, to investigate superelasticity and two-way shape memory behavior at reduced length scales in the context of NiTi by recourse to micro-compression, micro-indentation and TEM studies. Selected compositions of ternary NiTiFe shape memory …