Surface and double nonlocal effects on thermoelastic damping analysis of functionally graded sandwich microbeam resonators reinforced with graphene nanoplatelets

The sandwich nanocomposites reinforced with graphene nanoplatelets (GPLs) have been widely used as high -efficient resonators since its superior thermo-mechanical properties. Additionally, accurately prediction quality-factor based on thermoelastic damping (TED) is of great significance for the design and optimization of high-performance micro/nano-resonators. Nevertheless, the classical TED models fail on the micro/nano-scale due to without considering the influences of the size-dependent effects related to heat transfer and elastic deformation. In this work, a novel TED model is formulated to estimate the impact of size-dependent effects on the functionally graded (FG) sandwich micro-beam resonators reinforced with GPLs by combining the nonlocal dual-phase-lag (NDPL) heat conduction model, the nonlocal elasticity model and the modified coupled stress theory (MCST). It is assumed that the FG sandwich microbeam resonator consist of a pure silicon core and FG reinforced with GPLs surfaces. The energy equation and the transverse motion equation are formulated by employing the modified generalized thermoelasticity, and then, the analytical solution of TED is solved by complex frequency method. The influences of the various factors including the nonlocal thermal parameter, the nonlocal elasticity parameter, the surface effect, the total weight fraction of GPLs and the vibration modes on the TED are discussed in detail. The results indicate that the TED of the FG sandwich microbeam resonator reinforced with GPLs strongly depends on the size-dependent effects and the total weight fraction of GPLs. Moreover, the energy dissipation can be reduced by the size-dependent effects of the microbeam resonator.