Dynamic actuation properties of Ni-Mn-Ga ferromagnetic shape memory alloys
Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2002.
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| Format: | Thesis |
| Language: | eng |
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Massachusetts Institute of Technology
2005
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| Online Access: | http://hdl.handle.net/1721.1/8442 |
| _version_ | 1811069955438804992 |
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| author | Henry, Christopher P. (Christopher Paul), 1974- |
| author2 | Samuel M. Allen and Robert C. O'Handley. |
| author_facet | Samuel M. Allen and Robert C. O'Handley. Henry, Christopher P. (Christopher Paul), 1974- |
| author_sort | Henry, Christopher P. (Christopher Paul), 1974- |
| collection | MIT |
| description | Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2002. |
| first_indexed | 2024-09-23T08:19:32Z |
| format | Thesis |
| id | mit-1721.1/8442 |
| institution | Massachusetts Institute of Technology |
| language | eng |
| last_indexed | 2024-09-23T08:19:32Z |
| publishDate | 2005 |
| publisher | Massachusetts Institute of Technology |
| record_format | dspace |
| spelling | mit-1721.1/84422022-01-13T07:54:33Z Dynamic actuation properties of Ni-Mn-Ga ferromagnetic shape memory alloys Dynamic actuation response of Ni-Mn-Ga ferromagnetic shape memory alloys Henry, Christopher P. (Christopher Paul), 1974- Samuel M. Allen and Robert C. O'Handley. Massachusetts Institute of Technology. Dept. of Materials Science and Engineering. Massachusetts Institute of Technology. Department of Materials Science and Engineering Materials Science and Engineering. Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2002. Includes bibliographical references (leaves 198-201). Dynamic magnetic-field-induced strain actuation of up to 3% with a frequency bandwidth of least 500 Hz in Ni48.5Mn29.5Ga21 ferromagnetic shape memory alloys (FMSAs) is achieved. Hardware was designed and constructed to measure frequency bandwidth, magnetic-field-induced strain, stress and magnetization driven from an applied magnetic field. The bandwidth in this investigation was only limited by inductive reactance of the hardware, not by fundamental limitations of Ni-Mn-Ga. Degradation of the peak dynamic actuation strain occurred from 3.0% to 2.6% with increasing number of cycles from Nz1,000 to N 100,000. Measurement of strain, stress, and magnetization driven by a magnetic field permitted the comparison of measured properties versus properly defined thermodynamic properties. The peak thermodynamic piezomagnetic coefficient is d3, 1,= 2.5 x 10-7m / A compared to the experimental slope, dE/dH, of 1.0 x 10-7 m / A at N-1,000 cycles and 1.4 x 10-7 m / A at N-100,000 cycles, respectively. The thermodynamic piezomagnetic coefficient is five times greater than Terfenol-D with d31 = 5.0 x 10-m / A. The magnetic susceptibility varies between 3-10, while the twinning stiffness varies between 30-40 MPa within the average bias stress range of 0.3 to 2.8 MPa. At optimum fields and bias stresses, the mechanical energy density during cyclic deformation was 65 kJ/m3 at the expense of 20 kJ/m3 lost An important first observation of dynamic stress vs. field behavior is understood by an extension of a magnetomechanical phenomenological model. (cont.) The mechanism of stress generation is thought to be magnetization rotation causing negative magnetostriction with quadratic magnetic-field dependence before twin boundaries move. Above the threshold field for twin boundary motion, stress increases in proportion to the magnetic-field-induced strain. Dynamic actuation measurements performed here help put Ni-Mn-Ga FSMAs into perspective with other active materials performance: Ni-Mn-Ga FSMAs are between low bandwidth, high strain, Nitinol and high bandwidth, low strain Terfenol-D and ferroelectrics. by Christopher P. Henry. Ph.D. 2005-08-23T20:13:14Z 2005-08-23T20:13:14Z 2002 2002 Thesis http://hdl.handle.net/1721.1/8442 50659165 eng M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission. http://dspace.mit.edu/handle/1721.1/7582 201 leaves 12350462 bytes 12350213 bytes application/pdf application/pdf application/pdf Massachusetts Institute of Technology |
| spellingShingle | Materials Science and Engineering. Henry, Christopher P. (Christopher Paul), 1974- Dynamic actuation properties of Ni-Mn-Ga ferromagnetic shape memory alloys |
| title | Dynamic actuation properties of Ni-Mn-Ga ferromagnetic shape memory alloys |
| title_full | Dynamic actuation properties of Ni-Mn-Ga ferromagnetic shape memory alloys |
| title_fullStr | Dynamic actuation properties of Ni-Mn-Ga ferromagnetic shape memory alloys |
| title_full_unstemmed | Dynamic actuation properties of Ni-Mn-Ga ferromagnetic shape memory alloys |
| title_short | Dynamic actuation properties of Ni-Mn-Ga ferromagnetic shape memory alloys |
| title_sort | dynamic actuation properties of ni mn ga ferromagnetic shape memory alloys |
| topic | Materials Science and Engineering. |
| url | http://hdl.handle.net/1721.1/8442 |
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