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Abstract: This paper studies free vibration of double-walled carbon nanotubes (DWCNTs) based nanomechanical sensor under initial axial stress. A bridged DWCNT carrying a nanoparticle at any position of the outer tube is modeled as two clamped nonlocal Euler–Bernoulli beams, and the interaction between two tubes is governed by van der Waals force. For comparison, a bridged single-walled carbon nanotube (SWCNT) based nanomechanical sensor is considered in a similar way. Using the transfer function method, the critical buckling stress and natural frequencies of these nanomechanical sensors are computed. Under small initial stress, the effects of the attached nanoparticle, and the small scale parameter on the frequency shift are discussed. The obtained results show that when the mass of the nanoparticle increases or its location is closed to the beam center, the natural frequency decreases, but frequency shift increases. Initial tensile stress increases the natural frequency, while initial compressive stress decreases the natural frequency. In comparison with SWCNT sensor, DWCNT is more stable, but less sensitive for smaller attached mass. Obtained results are helpful to the design of DWCNT-based resonator as nanomechanical sensor. [Copyright &y& Elsevier]

Abstract: The potential of single-walled carbon nanotube (SWCNT) as a micro-mass sensor is explored. A clamped-free SWCNT with an attached tip micro-mass is modeled as a microcantilever with a concentrated mass at the free end. Based on the nonlocal Timoshenko theory of beams, the transverse vibration of the SWCNT-based micro-mass sensor is analyzed. Using the transfer function method, the natural frequencies of a nonlocal Timoshenko cantilever with a tip mass are computed. The effects of the attached mass and rotary inertia on the natural frequencies are discussed. When the nonlocal effect is neglected, the frequencies reduce to the classical results, in agreement with those using the finite element method. The obtained results show that with increasing the attached micro-mass, the natural frequency decreases, but frequency shift increases. Decreasing the length-to-diameter ratio also increases the frequency shift. The effect of the nonlocal parameter is significant, especially for higher-order vibration modes. The nonlocal Timoshenko beam model is more adequate than the nonlocal Euler–Bernoulli beam model for short SWCNT sensors. Obtained results are helpful to the design of SWCNT-based resonator as micro-mass sensor. [Copyright &y& Elsevier]