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Abstract: An analytically nonlocal Euler–Bernoulli beam model for the wave propagation in fluid-filled single-walled carbon nanotube (SWCNT) is established. The governing equations with the nonlocal effects are derived on the variational principle, and used in the wave propagation analysis of the SWCNT beam. Compared with the partially nonlocal Euler–Bernoulli beam models used previously, the analytically nonlocal model presented in the present study predicts well the effects of the stiffness enhancement and the wave damping at the high wavenumber or the strong nonlocal effects area for the fluid-filled SWCNT beam. Though the analytical model is less sensitive than the partially nonlocal model when the moving velocity of the internal fluid is high enough, it simulates more of the high-order nonlocal effecting information than the partially nonlocal model does in many cases. [Copyright &y& Elsevier]

Abstract: This paper is concerned with the characteristics of wave propagation in double-walled carbon nanotubes (DWCNTs). The DWCNTs is simulated with a Timoshenko beam model based on the nonlocal continuum elasticity theory, referred to as an analytically nonlocal Timoshenko-beam (ANT) model. The governing equations of the DWCNTs beam consist of a set of four equations that are derived from the variational principle of the beam with high-order boundary conditions at the both ends, in which the effects of the nano-scale nonlocality and the van der Waals interaction between inner and outer tubes are inclusive. The characteristics of the wave propagation in the DWCNTs beam were analyzed with the new ANT model proposed and the comparisons with the partially nonlocal Timoshenko-beam (PNT) models in publication were made in details. The results show that the nonlocal effects of the ANT model proposed in the present study on the wave propagations are more significant because it is in stronger stiffness enhancement to the DWCNTs beam. [Copyright &y& Elsevier]

This paper is concerned with vibration analysis considering fluid–structure interaction (FSI) in liquid-filled pipe system using transfer matrix method (TMM) in frequency domain. The emphasis is placing specially upon the multi-span pipe system with middle rigid constraints. Three major mechanisms of coupling, the friction coupling, the Poisson coupling and the junction coupling, as well as both distributed and concentrated external excitations are considered in this study. A phenomenon associated with the rigid constraints, namely, a junction coupling depending on the Poisson coupling and friction coupling (might be called the conditional junction coupling), is revealed and discussed. Numerical examples indicate that the conditional junction coupling has much larger influence on the frequencies of a liquid-filled pipe system than the Poisson coupling does. It is also shown through the numerical examples that the proposed method is efficient. [Copyright &y& Elsevier]