Vibration analysis of FGM beams incorporating surface energy immersed in fluids under photothermal excitation

In this study, the dynamic response of FGM (functionally graded materials) beam with surface effect immersed in fluids under high-frequency photothermal excitation is investigated theoretically. The governing equations of FGM beams are derived under Euler–Bernoulli beam theory. The cubical assumption is adopted to describe stress along thickness of FGM beam. In consideration of photothermal force and hydrodynamic load, the solution of forced vibration is obtained by means of the Fourier series expansion of variables. Theoretical analysis shows that the volume fraction and surface effect have an important influence on the response of beams immersed in different fluids; for the FGM material, an optimal material distribution proportion can maximize the response of beams. Among the parameters of the surface effect, the influence of surface residual is greater than surface elastic modulus and surface density. The influence of fluids on resonant frequencies is much more significant than surface effect. This study can provide some references to the application of micro- and nano-FGM structures in Micro-Electro-Mechanical System and Nano-Electro-Mechanical System.