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Micro‑mass sensor‑based vibration response of smart bidirectional functionally graded auxetic microbeams

Wei Y. Y., Al-Furjan M. S. H., Shan L., Shen X., Kolahchi R., Rabani bidgoli M., Farrokhian A.

Archives of Civil and Mechanical Engineering

2024

Vol. 24, no. 1

art. no. e38, 2024

Microsensor-based vibration of 2D smart functionally graded sandwich microbeam with attached microparticles is investigated using the strain gradient hypothesis. The application of micro-materials as active sensing particles in micro-sensors has increased the sensitivity performance of micro-sensors that can be able to detect particles, for example, bacteria with very nano-dimensions and low concentrations. The sandwich beam contains a negative Poisson’s ratio auxetic honeycombs covered by a piezoelectric smart layer at the top and a bidirectional functionally graded material (FGM) layer at the bottom layers. Partial differential equations of the simply supported sandwich beams are first attained using the energy method utilizing refined zigzag theory. The coupled final equations are solved analytically utilizing Galerkin’s technique to present the frequency. The impact of the position and mass of the microparticles, applied voltage, material distribution in the bottom layer, size scale parameter, the honeycomb auxetic core geometrical properties, and the layer thickness on the frequency are discussed. The obtained findings showed that by enhancing the mass of the nanoparticle, the frequency is reduced. In addition, the location of the nanoparticle on the beam is important so that when it is close to the beam center, the frequency decreases. Further, by enhancing the thickness of the face sheet, the microbeam frequency decreases but increasing the core layer thickness plays an inverse role. Besides, it is found that when the material in-homogeneity index P x or P z in the 2D-FGM layer is enhanced, the frequency decreases.

Energy absorption, free and forced vibrations of flexoelectric nanocomposite magnetostrictive sandwich nanoplates with single sinusoidal edge on the frictional torsional viscoelastic medium

Chu C., Shan L., Al‑Furjan M. S. H., Farrokhian A., Kolahchi R.

Archives of Civil and Mechanical Engineering

2023

Vol. 23, no. 4

art. e223, 1--28

Most studies on the nanoscale mainly focus on regular rectangular nanoplates, but according to the synthesis of nanostructures, the dynamic response of non-rectangular nanoplates is noticeable and there are not many works on these complex nanostructures. This work presents energy absorption, and forced and free vibrations of sandwich non-rectangular nanoplates with a single sinusoidal edge resting on a fractional torsional viscoelastic medium. The nanostructure is made from alumina reinforced by graphene platelets (GPLs) as a core covered by the flexoelectric and magnetostrictive materials as top and bottom layers, respectively. The consideration of size effects is derived from the innovative theory of local/nonlocal phenomena in a two-phase context. The Halpin-Tsai micromechanical and Kelvin–Voigt models are applied for the effective characteristics of the material in the nanocomposite layer and structural damping, respectively. Based on Hamilton’s principle and refined zigzag theory (RZT), the coupled electro-magneto-mechanical equations of motion are gained and analyzed by Galerkin’s and Newmark’s procedures. The effects of different components, including factors related to both the nonlocal and local phase fractions, the volume fraction of GPLs, various elastic mediums, electric field, structural damping, magnetic field, piezoelectric and flexoelectric effects on the absorption of energy, and forced and free vibrations of the sandwich nanostructure. Numerical simulations demonstrate that optimal energy absorption occurs when the flexoelectric factor is set to zero and the piezoelectric constant is non-zero but of opposite polarity. Additionally, it is concluded that when the coefficient of the local phase fraction is zero, increasing the nonlocal factor has more influence on the energy absorption and vibration of the nanostructure.