Functionally graded shape memory alloys (FG-SMA) have the properties of both functionally graded materials and shape memory alloys (SMA)

so they have been widely used in aerospace

biomedical

and micro electro mechanical systems(MEMS). The influence of surface effects on the mechanical properties of microstructure is very significant when the scale reaches the nanometer scale. In order to study the effect of surface effects on the mechanical properties of FG-SMA

based on the bending theory and Gurtin-Murdoch surface elasticity theory

the phase transition mechanical model considering the effects of tensile and compressive asymmetry and temperature on FG-SMA nanobeams was developed considering the surface effects. The influence of functionally graded index

load

temperature

and tensile-compression asymmetry coefficient on the mechanical properties of FG-SMA nanobeams was analyzed. It is shown that bending moment and functionally graded index have significant effects on the cross-sectional response

while temperature and tensile asymmetry coefficient have fewer effects on them. Ignoring the influence of surface effect will underestimate the flexural resistance of FG-SMA nanobeams. When the bending moment reaches a certain range

the neutral axis deflection of FG-SMA nanobeams is not much affected by surface effects. The results of the study provide a basis for the design and application of FG-SMA nanobeams in the field of MEMS.