Abstract:Shape Memory Alloys have excellent characteristics, such as low phase transition temperature, high output stress, low energy consumption, low driving voltage, large recoverable strain, and good bio-compatibility. With the further development of the Shape Memory Alloy technology, some scholars proposed that the functional gradient shape memory alloy material used in the micro-electro-mechanical system and other intelligent micro-structure will make it have better characteristics. Therefore, the study of nonlinear free vibration characteristics of electro-mechanical coupling FG-SMA micro-structures is of importance. Based on the von Karman geometric nonlinear theory, considering the influence of electrostatic force, intermolecular force and the size effect, the functional gradient shape memory alloy micro-beam model fixed at both ends is established. The multi-field coupling nonlinear vibration before and after the phase transformation of the alloy micro-beams is studied in depth. The effects of size effect parameters, geometrical parameters and phase-change parameters on the free vibration characteristics of the functional gradient shape memory alloy micro-beams are analyzed.