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Characterization of a 3D Multi-Mechanism SMA Material Model for the Prediction of the Cyclic "Evolutionary" Response of NiTi for Use in Actuations

Dhakal, Binod
http://rave.ohiolink.edu/etdc/view?acc_num=akron1384506213

Abstract Details

2013, Doctor of Philosophy, University of Akron, Civil Engineering.
Among the various combinations of metals used to form alloys, certain combinations, such as Ni and Ti, are known to exhibit unique properties, like the ability to remember a shape after deformation. Because of these novel and unique properties, they are known as `Shape Memory Alloys (SMAs)’ and are desirable for use in various fields of engineering application; eg., in sensors, actuators, biomedical stents and devices, energy absorption, vibration damping, etc, as they can absorb and dissipate mechanical/thermal energies by undergoing a reversible hysteretic shape change under the applied mechanical/thermal cyclic loadings. This reflects the effects of microstructural changes occurring during phase transformation between Austenite (A) and Martensite(M) phases, as well as the martensite-variants orientations at high stress levels ( Mi to Mj, where i and j are different variants). As typically utilized in applications, a particular shape memory alloy (SMA) device or component also need to operate under a large number of thermo-mechanical cycles, hence, the importance of accounting for the cyclic behavior characteristics in modeling and characterization of these systems. This dissertation work focus on: (1) a detailed study of a recently-formulated, multi-mechanism-based, comprehensive, thus complex modeling framework formulated by Saleeb et al, in particular the physical significance of the multiple, inelastic mechanisms that are used to regulate the partitioning of energy dissipation and storage governing the evolutionary thermo-mechanical response of shape memory behavior; (2) a comprehensive characterization of the cyclic response of the specific complex real shape memory alloy like Ni49.9Ti50.1, also commonly known as 55NiTi, for isobaric tests under the entire relevant bias stress range from 10 to 300MPa, and for sufficient number of thermal cycles (100 cycles here); (3) implementation of the calibrated SMA model in the study of its effectiveness in the large-scale simulations of SMA actuators of coil-spring and tube configurations; and (4) experimental validation for the calibrated SMA model for the large-scale simulation for helical-coil spring actuation. This study proved that the SMA model is capable to characterize the thermo-mechanical behavior of the complex alloy system and can be implemented to analyze large scale applications which involve inhomogeneous, multi-axial stress states and large deformation.
Atef F Saleeb, Dr. (Advisor)
Wieslaw K. Binienda, Dr. (Committee Member)
Ernian Pan, Dr. (Committee Member)
Xiaosheng Gao, Dr. (Committee Member)
Kevin L. Kreider, Dr. (Committee Member)
170 p.
Aerospace Engineering; Aerospace Materials; Civil Engineering; Materials Science
multi-axial, multi-mechanism, material modeling, characterization, 55NiTi, shape memory alloy, thermomechanical, isobaric, thermal cycles, evolution, actuation

Recommended Citations

Citations

  • Dhakal, B. (2013). Characterization of a 3D Multi-Mechanism SMA Material Model for the Prediction of the Cyclic "Evolutionary" Response of NiTi for Use in Actuations [Doctoral dissertation, University of Akron]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=akron1384506213

    APA Style (7th edition)

  • Dhakal, Binod. Characterization of a 3D Multi-Mechanism SMA Material Model for the Prediction of the Cyclic "Evolutionary" Response of NiTi for Use in Actuations. 2013. University of Akron, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=akron1384506213.

    MLA Style (8th edition)

  • Dhakal, Binod. "Characterization of a 3D Multi-Mechanism SMA Material Model for the Prediction of the Cyclic "Evolutionary" Response of NiTi for Use in Actuations." Doctoral dissertation, University of Akron, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=akron1384506213

    Chicago Manual of Style (17th edition)

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This open access ETD is published by University of Akron and OhioLINK.
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