A nonlinear dynamicsmodelwas derived based on the constitutive equations of the thermo-
mechanical and pseudoelastic behaviors of shape memory alloy (SMA) and the dynamic equilibrium
equations of an SMA beam. The analytic results show that the transverse vibration stability of the beam
corresponds to the equilibriums of the phase transformations. At lower temperaturewheremartensite is
stable, there are three fixed points: one representing stable center and the other two describing
unstable saddle points. At themiddle temperature where bothmartensite and austenite coexis,t there
are five fixed points: three representing stable centers and the other two describing unstable saddle
points. Athigh temperaturewhere austenite is the exclusive stable phase, there is only one fixed point
representing a stable cent