Thermo-Mechanical Behavior and Shakedown of Shape Memory Alloy Cable Structures
DANIEL BIGGS, DOCTOR OF PHILOSOPHY, AEROSPACE ENGINEERING
Abstract: Shape memory alloy (SMA) cables are relatively new structural elements that inherit the benefits of conventional stranded wire (increased failure tolerance and bending flexibility) and the adaptive properties of SMAs (superelasticity and shape memory effect). SMA wires generally have superior properties to their larger counterparts (SMA bars) due to materials processing limitations, which has been a longstanding barrier to scaling up SMA structural elements. SMA cables overcome these difficulties by leveraging the optimized properties of SMA wire in a compact packing form to generate large tensile forces at lower cost for equivalent size SMA bars. While superelastic SMA cables have been recently characterized, this research explores the behavior of SMA cables with higher transition temperatures that can be used in a shape memory mode as thermo-responsive, high force actuator elements. It also looks to better quantify how the local mechanical behavior in cables (extension, bending, twisting, and contact) impacts the stress-induced phase transformation through experimental measurements and simulations using the finite elements method. Furthermore, it examines the cyclic performance and degradation of thermal actuation through experiments using novel stress-temperature histories, revealing new path dependent transformation phenomena.
- Committee Chair: John Shaw
- Cognate member: Alan Wineman
- Members: Samantha Daly (UCSB), Nilesh Mankame (GM Corp), Veera Sundararaghavan
Biggs, D., Shaw, J., and Churchill, C. Heat Transfer of Springs in Oblique Crossflows. ASME Journal of Heat Transfer. (Manuscript in Review)
Mas, B., Biggs, D., Vieito, I., Cladera, A., Shaw, J., and Martínez-Abella F. Superelastic shape memory alloy cables for reinforced concrete applications. Construction and Building Materials. (Manuscript in Review)
Biggs, D. and Shaw, J. Experimental characterization of shape memory alloy actuator cables, In Proc. SPIE 9800, Behavior and Mechanics of Multifunctional Materials and Composites 2016, 98000D (April 18, 2016); doi:10.1117/12.2219502.
Biggs, D., Shaw, J., and Churchill, C. Convective Heat Transfer of Wires and Springs for use in SMA Heat Engines. In Proceedings of Shape Memory and Superelastic Technologies, pages 382–383. SMST, ASM International, May 2013.