Pasternak foundation effect on the axial and torsional waves propagation in embedded DWCNTs using nonlocal elasticity cylindrical shell theory

A. Ghorbanpour Arani,A. A. Mosallaie Barzoki,R. Kolahchi,A. Loghman 대한기계학회 2011 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.25 No.9

The axial and torsional wave propagation in a double-walled carbon nanotube (DWCNT) embedded on elastic foundations are investigated using nonlocal continuum shell theory. The effects of the surrounding elastic medium are considered using the spring constant of the Winkler-type and the shear constant of the Pasternak-type. The van der Waals (vdW) forces between the inner and the outer nanotubes are taken into account. The dynamic response of the carbon nanotube is formulated on the basis of nonlocal elasticity shell theory. The cut-off frequencies are obtained and it has been concluded that the cut-off frequencies are independent of small scale coefficient and shear modulus of the elastic medium. It has been found that the phase velocity sharply decreases by increasing the axial half wave number and approaches a constant value. It has also been concluded that the maximum phase velocity predicted by nonlocal theory is located between 5 and 10 nanometers while for local theories the phase velocity sharply decreases in this interval and approaches a constant value. Results show that the effect of Pasternak-type on phase velocity is significant but the effect of Winkler-type is not really considerable.

Semi-analytical solution of magneto-thermo-elastic stresses for functionally graded variable thickness rotating disks

A. Ghorbanpour Arani,A. Loghman,A. R. Shajari,S. Amir 대한기계학회 2010 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.24 No.10

In this paper, a semi-analytical solution for magneto-thermo-elastic problem in functionally graded (FG) hollow rotating disks with variable thickness placed in uniform magnetic and thermal fields is presented. Stresses and perturbation of magnetic field vector in FG rotating disks are determined using infinitesimal theory of magneto-thermo-elasticity under plane stress conditions. The material properties except Poisson’s ratio are modeled as power-law distribution of volume fraction. The profile of disk thickness is assumed to be a parabolic function of radius. The non-dimensional distribution of temperature, displacement, stresses and perturbation of magnetic field vector throughout radius are shown. Effects of material grading index, geometry of the disk and magnetic field on the stress and displacement fields are investigated. The results of stresses and radial displacements for two different boundary conditions with and without the effect of magnetic field are compared for a FG rotating disk with concave thickness profile. It has been found that imposing a magnetic field significantly decreases tensile circumferential stresses. Therefore the fatigue life of the disk will be significantly improved by applying the magnetic field. Results of this investigation could be applied for optimum design of FG hollow rotating disks with variable thickness.

Nonlinear vibration and instability of fluid-conveying DWBNNT embedded in a visco-Pasternak medium using modified couple stress theory

A. Ghorbanpour Arani,M. R. Bagheri,R. Kolahchi,Z. Khoddami Maraghi 대한기계학회 2013 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.27 No.9

Nonlinear free vibration and instability of fluid-conveying double-walled boron nitride nanotubes (DWBNNTs) embedded in viscoelastic medium are studied in this paper. The effects of the transverse shear deformation and rotary inertia are considered by utilizing the Timoshenko beam theory. The size effect is applied by the modified couple stress theory and considering a material length scale parameter for beam model. The nonlinear effect is considered by the Von Kármán type geometric nonlinearity. The electromechanical coupling and charge equation are employed to consider the piezoelectric effect. The surrounding viscoelastic medium is described as the linear visco-Pasternak foundation model characterized by the spring and damper. Hamilton’s principle is used to derive the governing equations and boundary conditions. The differential quadrature method (DQM) is employed to discretize the nonlinear higher-order governing equations, which are then solved by a direct iterative method to obtain the nonlinear vibration frequency and critical fluid velocity of fluid-conveying DWBNNTs with clamped-clamped (C-C) boundary conditions. A detailed parametric study is conducted to elucidate the influences of the small scale coefficient, spring and damping constants of surrounding viscoelastic medium and fluid velocity on the nonlinear free vibration, instability and electric potential distribution of DWBNNTs. This study might be useful for the design and smart control of nano devices.

Investigating Elastic Stability of Cylindrical Shell with an Elastic Core under Axial Compression by Energy Method

A. Ghorbanpour Arani,S. Golabi,Loghman,H. Daneshi 대한기계학회 2007 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.21 No.7

Nonlocal electro-thermal transverse vibration of embedded fluid-conveying DWBNNTs

A. Ghorbanpour Arani,M. Shokravi,S. Amir,M.R. Mozdianfard 대한기계학회 2012 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.26 No.5

"Electro-thermal transverse vibration of fluid-conveying double-walled boron nitride nanotubes (DWBNNTs) embedded in an elastic medium such as polyvinylidene fluoride (PVDF) which is a piezoelectric polymer is investigated. The elastic medium is simulated as a spring and van der Waals (vdW) forces between inner and outer nanotubes are also taken into account. Zigzag structure of boron nitride nanotubes (BNNTs) is described based on the nonlocal continuum piezoelasticity cylindrical shell theory, and Hamilton's principle is employed to derive the corresponding higher-order equations of motion. In this model, DWBNNTs are placed in uniform temperature and electric field, the latter being applied through attached electrodes at both ends. Having considered the small scale effect, aspect ratio (L/R ), densities of fluid and elastic medium, four different cases of loading are assumed in this study, including: a) direct voltage and heating (DVH), b) direct voltage and cooling (DVC), c) reverse voltage and heating (RVH), and d) reverse voltage and cooling (RVC). Numerical results indicate that increasing nonlocal parameter ( 0 e a ), for the four above mentioned cases, decreases the critical flow velocity of fluid. The results could be used in design of nano-electro-mechanical devices for measuring density of a fluid such as blood flowing through such nanotubes with great applications in medical fields."

Nonlinear viscose flow induced nonlocal vibration and instability of embedded DWCNC via DQM

A. Ghorbanpour Arani,R. Kolahchi,S. Haghighi,A. A. Mosallaie Barzoki 대한기계학회 2013 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.27 No.1

Nonlinear thermo free vibration and instability of viscose fluid-conveying double-walled carbon nanocones (DWCNCs) are studied using Hamilton’s principle and differential quadrature method (DQM). The small-size effects on bulk viscosity and slip boundary conditions of nanoflow through Knudsen number (Kn) is considered. The nanocone is simulated as a clamped-clamped Euler-Bernoulli's beam embedded in an elastic foundation of the Winkler and Pasternak type. The van der Waals (vdW) forces between the inner and outer nanocones are taken into account. The detailed parametric study is conducted, focusing on the combined effects of the nonlocal parameter, apex angles, aspect ratio, temperature change, fluid viscosity, boundary conditions and the elastic medium coefficient on the dimensionless frequency and critical fluid velocity of DWCNCs. The results show that the small-size effect on flow field is remarkable on frequency and critical fluid velocity of DWCNC. Also, the nonlinear frequency and critical flow velocity decrease with increasing the nonlocal parameter and cone semi-vertex angle. The results are in good agreement with the previous researches.

Buckling analysis of laminated composite rectangular plates reinforced by SWCNTs using analytical and finite element methods

A. Ghorbanpour Arani,Sh. Maghamikia,M. Mohammadimehr,A. Arefmanesh 대한기계학회 2011 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.25 No.3

In this paper, the buckling analysis of laminated composite plates reinforced by single-walled carbon nanotubes (SWCNTs) is carried out using an analytical approach as well as the finite element method. The developed model is based on the classical laminated plate theory (CLPT) and the third-order shear deformation theory for moderately thick laminated plates. The critical buckling loads for the symmetrical layup are determined for different support edges. The Mori-Tanaka method is employed to calculate the effective elastic modulus of composites having aligned oriented straight nanotubes. The effect of the agglomeration of the randomly oriented straight nanotubes on the critical buckling load is also analyzed. The results of analytical solution are compared and verified with the FEM calculations The critical buckling loads obtained by the finite element and the analytical methods for different layup and boundary conditions are in good agreement with each other. In this article, the effects of the carbon nanotubes (CNTs) orientation angle, the edge conditions,and the aspect ratio on the critical buckling load are also demonstrated using both the analytical and finite element methods.

Induced nonlocal electric wave propagation of boron nitride nanotubes

A. Ghorbanpour Arani,A. Hafizi Bidgoli,A. Karamali Ravandi,M. A. Roudbari,S. Amir,M. B. Azizkhani 대한기계학회 2013 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.27 No.10

Axial displacement and electric wave propagation of single-walled Boron-Nitride nanotubes (SWBNNTs) induced by alternating current (AC) are investigated in this study. A single- walled zigzag structure BNNT is modeled based on nonlocal piezoelasticity theory and Euler-Bernoulli beam (EBB). Equations correspond to lateral displacement have been obtained. Using Hamilton’s principle and considering charge equation for coupling of electrical and mechanical fields, the higher order of governing equations are derived. Analytical solution is applied to solve governing equations. Also the axial and lateral displacement of a SWBNNT and electric potential induced by AC through it are presented. The detailed parametric study is conducted, focusing on the remarkable effects of the half wave number on the behavior of the SWBNNT. The results indicate applying alternating field, leads to propagation of axial displacement along the SWBNNT. Also the result of this study can be useful to design and manufacture of smart micro/nano-electro-mechanical systems in advanced biomechanics applications by controlling axial and lateral displacements.

The effect of CNT volume fraction on the magneto-thermo-electro-mechanical behavior of smart nanocomposite cylinder

Arani A. Ghorbanpour 대한기계학회 2012 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.26 No.8

In this article, using analytical approach, the stress analysis of a long piezoelectric polymeric hollow cylinder reinforced with carbon nanotube (CNT) under combined magneto-thermo-electro-mechanical loading is investigated. Considering three combined loading conditions such as pressure-electric, pressure-electric magnetic and pressure-electric thermal, the governing equation of the problem is obtained. The rule of mixture and modified multiscale bridging model are used to predict effective properties of nanocomposite. The magneto-thermo-electro-mechanical stresses in hollow cylinder are discussed in detail. It can be concluded that increasing CNT volume fraction enhances strength of the nanocomposite cylinder. The results of this work could be useful in view of optimum design of the smart nanocomposite cylinder under magneto-thermo-electro-mechanical loadings and could also be as a reference for future related works.

Electro-thermo nonlocal nonlinear vibration in an embedded polymeric piezoelectric micro plate reinforced by DWBNNTs using DQM

A. Ghorbanpour Arani,H. Vossough,R. Kolahchi,A. A. Mosallaie Barzoki 대한기계학회 2012 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.26 No.10

In the present paper, electro-thermo nonlinear vibration of a piezo-polymeric rectangular micro plate made from polyvinylidene fluoride (PVDF) reinforced by zigzag double walled boron nitride nanotubes (DWBNNTs) is studied. This plate is embedded in an elastic medium which is simulated by Winkler and Pasternak foundation models. Using nonlinear strain-displacement relations and nonlocal elasticity plate theory as well as considering charge equation for coupling between electrical and mechanical fields, the motion equations are derived based on energy method and Hamilton's principle. The differential quadrature method (DQM) is employed to computation of nonlinear frequency for different mechanical and free-free electrical boundary conditions. The results indicate that smart composite and consequently the generated Φ improved sensor and actuator applications in several process industries, because it increases the nonlinear vibration frequency. Furthermore, it can be also found that the nonlinear frequency increases as the values of the elastic medium constants,the geometrical aspect ratios and DWBNNTs volume fraction increase but it decreases as nonlocal parameter increases.