MIT OpenCourseWarehttp://ocw.mit.edu3.22 Mechanical Properties of MaterialsSpring 2008For information about citing these materials or our Terms of Use, visit: http://ocw.mit.edu/terms.3.22 Mechanical Behavior of MaterialsSuperelastic Materials: Shape Memory AlloysMIT Department of Mechanical EngineeringMIT Department of Material Sciences and EngineeringCambridge, MA 02139 USAMay 2008Photo from http://www.meko.de/stents/meko_home_highend_main.htm accessed May 5, 2008Image removed due to copyright restrictions. Please see http://www.meko.de/bilder/meko_niti_rem_12x_300.jpg3.22Phenomenology and Applications[1] Humbeeck, J. V. “Shape Memory Alloys: A Material and a Technology.” Advanced Engineering Materials 3 (2001): 837-850. Eye glasses Piano wireDampereTemperaturAustenite %0100sAfMfAsMεσMA →MA←StentsTemperature andelectricalactuatorsCouplings Fastenershttp://en.vniief.ru/activity/Civil/Technologies/materials/http://mbstores.com/nireiiipofls.htmlhttp://www.meko.de/stents/meko_home_highend_main.htmMaterials:•NiTi•Cu-based•Cu-Al-Ni•Fe-Mn-Si•NiTi-Zr•Cu-Zr•Ni-AlPlease see Fig. 6 in [1] and http://www.meko.de/bilder/meko_niti_rem_12x_300.jpgPlease see Fig. 5 in [1] and http://www.vniief.ru/netcat_files/Image/3(31).jpgPlease see Fig. 7 in [1] and http://tbn0.google.com/images?q=tbn:hWpc6X7GZNrCnM:http://lib.store.yahoo.net/lib/mbstores-store/flexon2Please see Fig. 3 in [1]Please see Fig. 4 in [1] and any photo of an SMA actuator.Microscopic Mechanism[2] McCormick, J. P. “Cyclic Behavior of Shape Memory Alloys.” Ph.D. Thesis, Georgia Tech, 2006.3.22Monoclinic Crystal StructuresCubic Crystal StructureImage removed due to copyright restrictions. Please see Fig. 2-2 in [2].Characterization for Prediction by FEA3.22gisoeq×=σσ()⎥⎦⎤⎢⎣⎡−−≡−σyag 1(1cos31cos13)det(227σσσDy ≡()()(())()]21212231223233112332222211321σσσσσσσσσσ+++−+−+−⎢⎣⎡≡01σσ02σσNiTiCu-Al-Be600CCu-Al-BeRoom T-1.5-1-0.500.511.5-1.5 -1 -0.5 0 0.5 1 1.5Cu-Al-Be 32CCu-Al-Be 35CCu-Al-Be 60CNiTiMises Yield ModelTresca Yield ModelTaillard Yield Model02σσ01/σσ[3] Taillard, K. et. al. “Phase Transformation yield surface of anisotropic shape memory alloys.” Materials Science and Engineering A 438-440 (2006): 436-440.Courtesy Elsevier, Inc., http://www.sciencedirect.com. Used with permission.
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