Thermoelastic resonance analysis of BNNT-reinforced nanocomposite beams heated by internal thermal source

Abstract

The nanocomposite structures due to excellent chemical and thermal resistant have considerable potential for use in an aggressive environment with high corrosion and temperature gradient. This study analyzes subharmonic (Ω/ωL=2 and 3) and superharmonic (Ω/ωL=1/2 and 1/3) resonance behavior of boron nitride nanotube-reinforced composite (BNNT-RC) beams under harmonic excitation and internal thermal source. The thermal analysis is carried out for determining the temperature change using the two-dimensional heat conduction equation with the assumption of an arbitrary variation in the thickness direction. In the framework of adjacent equilibrium configurations and Galerkin method, the modified couple stress Timoshenko beam equations are reduced to one nonlinear decoupled equation. Next, closed-form relations of vibration amplitude (a) and detuning parameter (σ∼) are developed for subharmonic and superharmonic excitations using the multiple-scale perturbation technique. The nonlinear frequency and resonance responses are verified by comparison with the existing ones in the literature. Finally, parametric studies are presented to discuss the effects of length scale parameter, temperature change, energy rate of thermal source, detuning parameter, and geometric ratios. The snap-through buckling behavior is observed in the curves of ωNL/ω∗-ΔT and different unstable paths exist after the occurrence of instability. The thermoelastic effect can increase the stability range of harmonic load amplitude for various values of detuning parameter and it is more pronounced for the temperature variation induced by an internal thermal source.