Shape memory alloy (SMA) heat engines possess an inherent property of sensing a change in temperature, performing work, and rejecting heat through the shape memory effect resulting from a temperature-induced phase transformation. This work presents a framework for the design and implementation of an SMA-based Stirling heat engine for maximum power or speed incorporating and combining mechanical, thermal, and material aspects. The motivation for this work comes from the growing need for reliable thermal management and energy recovery in both ground and space applications of interest to NASA and commercial space companies. In future lunar and Mars missions, an SMA heat engine can be used in cryogenic liquefaction, densification, and zero boil-off (ZBO) systems for advanced spaceport applications. Terrestrial applications include energy recovery by transforming the excessive or rejected heat into mechanical work. Mechanical aspects were addressed by performing force balances in the SMA element and focused on the resulting stress distribution. Thermal aspects were addressed by considering the temperature distribution and the heat transfer rate between the SMA element and the heat source or the heat sink. Materials issues were addressed by considering principles of classical thermodynamics and the roles of internal and external stresses especially the hysteresis between the forward and reverse phase transformation and the stored elastic strain energy. The role of microstructure through composition, precipitates present, variant interfaces and training are also emphasized. The aforementioned aspects were combined to present a figure of merit to aid in the design and implementation of an SMA Stirling heat engine. The implementation presented considers a low temperature, low hysteresis R-phase transformation in the NiTiFe system for rejecting heat from a system. Support from the Fulbright Program is gratefully acknowledged.


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Graduation Date





Vaidyanathan, Raj


Master of Science in Materials Science and Engineering (M.S.M.S.E.)


College of Engineering and Computer Science


Materials Science and Engineering

Degree Program

Materials Science and Engineering


CFE0009852; DP0028146





Release Date

November 2023

Length of Campus-only Access


Access Status

Masters Thesis (Open Access)