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حرية الوصول المقاله
1 - Mechanical Buckling of Circular Orthotropic Bilayer Nanoplate Embedded in an Elastic Matrix under Radial Compressive Loading
M. Ahmadpour M.E. Golmakani M.N. Sadraee FarThis article investigates the buckling behavior of orthotropic annular/circular bilayer graphene sheet embedded in Winkler–Pasternak elastic medium under mechanical loading. Using the nonlocal elasticity theory, the bilayer graphene sheet is modeled as a nonlocal أکثرThis article investigates the buckling behavior of orthotropic annular/circular bilayer graphene sheet embedded in Winkler–Pasternak elastic medium under mechanical loading. Using the nonlocal elasticity theory, the bilayer graphene sheet is modeled as a nonlocal orthotropic plate which contains small scale effect and van der Waals interaction forces. Differential Quadrature Method (DQM) is employed to solve the governing equations for various combinations of simply supported or clamped boundary conditions. The results show that small scale parameter does not have any effect on critical buckling load of cases without elastic medium in simply supported boundary condition. Also, increase of vdW coefficient leads to increase of critical buckling load smoothly then it has no impact on critical buckling load after a certain value. تفاصيل المقالة -
حرية الوصول المقاله
2 - Bending and Buckling Analysis of a Nth-Order Shear Deformation Nanoplate using Modified Couple Stress Theory
Majid Eskandari shahraki mahmoud shariati naser asiabanIn this paper a Nth order nanoplate model is developed for the bending and buckling analysis of a graphene nanoplate based on a modified couple stress theory. The strain energy, external work and buckling equations are solved. Also using Hamilton’ principle, main أکثرIn this paper a Nth order nanoplate model is developed for the bending and buckling analysis of a graphene nanoplate based on a modified couple stress theory. The strain energy, external work and buckling equations are solved. Also using Hamilton’ principle, main and auxiliary equations of nano plate are obtained. The bending rates and dimensionless bending values under uniform surface traction and sinusoidal load, the dimensionless critical force under a uniaxial surface force in x direction are all obtained for various plate's dimensional ratios and material length scale to thickness ratios. The governing equations are numerically solved. The effect of material length scale, length, width and thickness of the nanoplate on the bending and buckling ratios are investigated and the results are presented and discussed in details. تفاصيل المقالة -
حرية الوصول المقاله
3 - Bending and Vibration Analysis of a Mindlin Rectangular Nanoplate using Modified Couple Stress Theory and Navier's Solution
Majid Eskandari Shahraki Mahmoud Shariati naser asiabanIn this paper, a Mindlin rectangular nanoplate model is developed for the bending and vibration analysis of a graphene nanoplate based on a modified couple stress theory. In order to consider the small scale effects, the modified couple stress theory, with one length sc أکثرIn this paper, a Mindlin rectangular nanoplate model is developed for the bending and vibration analysis of a graphene nanoplate based on a modified couple stress theory. In order to consider the small scale effects, the modified couple stress theory, with one length scale parameter, is used. In modified couple stress theory, strain energy density is a function of strain tensor, curvature tensor, stress tensor and symmetric part of couple stress tensor. After obtaining the strain and kinetic energy, external work and substituting them in the Hamilton’s principle, the main and auxiliary equations of the nanoplate are obtained. Then, by manipulating the boundary conditions the governing equations are solved using Navier approach for bending and vibration of the nanoplate. The bending rates and dimensionless bending values under uniform surface traction and sinusoidal load and different mode frequencies are all obtained for various plate's dimensional ratios and material length scale to thickness ratios. The effect of material length scale, length, width and thickness of the nanoplate on the bending and vibration ratios are investigated and the results are presented and discussed in details. تفاصيل المقالة -
حرية الوصول المقاله
4 - Vibrations of Multi-Layer Beam with Nanocomposite Face Sheets Reinforced with Graphene Platelets and Porous Core
A Mihankhah Z Khoddami Maraghi A Ghorbanpour Arani Sh NiknejadThe current article investigates the free vibrations of a three-layer beam. The middle layer of this structure is selected from porous material. For modeling the porous layer, linear pro-elasticity relationships are applied, while Young's modulus and its density vary al أکثرThe current article investigates the free vibrations of a three-layer beam. The middle layer of this structure is selected from porous material. For modeling the porous layer, linear pro-elasticity relationships are applied, while Young's modulus and its density vary along the thickness. The upper and lower layers of the structure are reinforced with graphene nanoplates and can take different configurations as Parabolic, linear, and uniform. In this study, with the help of Halpin-Tsai modified theory, equivalent composite coefficients will be extracted. The equations of motion in three layers are derived with the help of third order shear theory, energy method and Hamilton's Principle. Among the significant results of this article, we can mention the effect of amplifiers in improving the vibration behavior of the beam, the effect of pore pressure and volume fraction of reinforcement on the frequency of vibrations. The results of this research can be applied in marine, aerospace, and civil industries. تفاصيل المقالة -
حرية الوصول المقاله
5 - Analysis of Nanoplate with a Central Crack Under Distributed Transverse Load Based on Modified Nonlocal Elasticity Theory
M Rajabi H Lexian A RajabiIn this paper, using the complete modified nonlocal elasticity theory, the deflection and strain energy equations of rectangular nanoplates, with a central crack, under distributed transverse load were overwritten. First, the deflection of nanoplate was obtained using L أکثرIn this paper, using the complete modified nonlocal elasticity theory, the deflection and strain energy equations of rectangular nanoplates, with a central crack, under distributed transverse load were overwritten. First, the deflection of nanoplate was obtained using Levy's solution and consuming it; strain energy of nanoplate was found. As regards nonlocal elasticity theory wasn’t qualified for predicting the static behavior of nanoplates under distributed transverse load, using modified nonlocal elasticity theory, the deflection of nanoplate with a central crack for different values of the small-scale effect parameter was achieved. It was gained with the convergence condition for the complete modified nonlocal elasticity theory. To verify the result, the results for the state of the small-scale effect parameter were placed equal to zero (plate with macro-scale) and then were compared with the numerical results as well as the classical analytical solution results available in the valid references. It was shown that the complete modified nonlocal elasticity theory does not show any singularity at the crack-tip unlike the classical theory; therefore, the method presented is a suitable method for analysis of the nanoplates with a central crack. تفاصيل المقالة -
حرية الوصول المقاله
6 - On the Aeroelastic Stability of a Two-Directional FG GNP-Enriched Conical Shell
A.R Shahidi A DarakhshIn this article, the supersonic flutter analysis of a truncated conical shell made of polymer enriched with graphene nanoplatelets (GNPs) exposed to supersonic fluid flow is discussed. It is assumed that the mass fraction of the GNPs is functionally graded (FG) along th أکثرIn this article, the supersonic flutter analysis of a truncated conical shell made of polymer enriched with graphene nanoplatelets (GNPs) exposed to supersonic fluid flow is discussed. It is assumed that the mass fraction of the GNPs is functionally graded (FG) along thickness and length directions according to different dispersion patterns. Modeling of the shell is done using the first-order shear deformation theory (FSDT), the mechanical properties are computed according to the Halpin-Tsai model alongside the rule of the mixture, and the aerodynamic pressure is computed utilizing the piston theory. Utilizing Hamilton’s principle, the boundary conditions and the governing equations are achieved. Harmonic trigonometric functions are used to provide an analytical solution in the circumferential direction and an approximate solution is presented in the meridional direction using the differential quadrature method (DQM). The efficacy of various parameters on the aeroelastic stability are discussed such as the percentage and dispersion pattern of the GNPs and gradient indices. It is observed that to achieve higher aeroelastic stability in the GNP-enriched truncated conical shells, it is better to dispense the GNPs near the small radius and the inner surface of the shell. تفاصيل المقالة -
حرية الوصول المقاله
7 - Small Scale Effect on the Vibration of Orthotropic Plates Embedded in an Elastic Medium and Under Biaxial In-plane Pre-load Via Nonlocal Elasticity Theory
M Mohammadi M Goodarzi M Ghayour S AlivandIn this study, the free vibration behavior of orthotropic rectangular graphene sheet embedded in an elastic medium under biaxial pre-load is studied. Using the nonlocal elasticity theory, the governing equation is derived for single-layered graphene sheets (SLGS). Diffe أکثرIn this study, the free vibration behavior of orthotropic rectangular graphene sheet embedded in an elastic medium under biaxial pre-load is studied. Using the nonlocal elasticity theory, the governing equation is derived for single-layered graphene sheets (SLGS). Differential quadrature method (DQM) has been used to solve the governing equations for various boundary conditions. To verify the accuracy of the present results, a Navier’s approach is also developed. DQM results are successfully verified with those of the Navier’s approach. The results are subsequently compared with valid result reported in the literature. The effects of the small scale, pre-load, Winkler and Pasternak foundations and material properties on natural frequencies are investigated. The results are shown that with the decrease of in-plane pre-loads the curves isotropic and orthotropic non-dimensional frequency in approaches close to each other. تفاصيل المقالة -
حرية الوصول المقاله
8 - Surface Stress Effect on the Nonlocal Biaxial Buckling and Bending Analysis of Polymeric Piezoelectric Nanoplate Reinforced by CNT Using Eshelby-Mori-Tanaka Approach
M Mohammadimehr B Rousta Navi A Ghorbanpour AraniIn this article, the nonlocal biaxial buckling load and bending analysis of polymeric piezoelectric nanoplate reinforced by carbon nanotube (CNT) considering the surface stress effect is presented. This plate is subjected to electro-magneto-mechanical loadings. Eshelby- أکثرIn this article, the nonlocal biaxial buckling load and bending analysis of polymeric piezoelectric nanoplate reinforced by carbon nanotube (CNT) considering the surface stress effect is presented. This plate is subjected to electro-magneto-mechanical loadings. Eshelby-Mori-Tanaka approach is used for defining the piezoelectric nanoplate material properties. Navier’s type solution is employed to obtain the critical buckling load of polymeric piezoelectric nanoplate for classical plate theory (CPT) and first order shear deformation theory (FSDT). The influences of various parameters on the biaxial nonlocal critical buckling load with respect to the local critical buckling load ratio () of nanoplate are examined. Surface stress effects on the surface biaxial critical buckling load to the non-surface biaxial critical buckling load ratio () can not be neglected. Moreover, the effect of residual surface stress constant on is higher than the other surface stress parameters on it. increases by applying the external voltage and magnetic fields. The nonlocal deflection to local deflection of piezoelectric nanocomposite plate ratio () decreases with an increase in the nonlocal parameter for both theories. And for FSDT, decreases with an increase in residual stress constant and vice versa for CPT. تفاصيل المقالة -
حرية الوصول المقاله
9 - Size-Dependent Analysis of Orthotropic Mindlin Nanoplate on Orthotropic Visco-Pasternak Substrate with Consideration of Structural Damping
A Ghorbanpour Arani M.H Jalaei S Niknejad A.A Ghorbanpour AraniThis paper discusses static and dynamic response of nanoplate resting on an orthotropic visco-Pasternak foundation based on Eringen’s nonlocal theory. Graphene sheet modeled as nanoplate which is assumed to be orthotropic and viscoelastic. By considering the Mindl أکثرThis paper discusses static and dynamic response of nanoplate resting on an orthotropic visco-Pasternak foundation based on Eringen’s nonlocal theory. Graphene sheet modeled as nanoplate which is assumed to be orthotropic and viscoelastic. By considering the Mindlin plate theory and viscoelastic Kelvin-Voigt model, equations of motion are derived using Hamilton’s principle which are then solved analytically by means of Fourier series -Laplace transform method. The parametric study is thoroughly accomplished, concentrating on the influences of size effect, elastic foundation type, structural damping, orthotropy directions and damping coefficient of the foundation, modulus ratio, length to thickness ratio and aspect ratio. Results depict that the structural and foundation damping coefficients are effective parameters on the dynamic response, particularly for large damping coefficients, where response of nanoplate is damped rapidly. تفاصيل المقالة -
حرية الوصول المقاله
10 - Vibration Analysis of a Rotating Nanoplate Using Nonlocal Elasticity Theory
M Ghadiri N Shafiei S Hossein AlaviThe nanostructures under rotation have high promising future to be used in nano-machines, nano-motors and nano-turbines. They are also one of the topics of interests and it is new in designing of rotating nano-systems. In this paper, the scale-dependent vibration analys أکثرThe nanostructures under rotation have high promising future to be used in nano-machines, nano-motors and nano-turbines. They are also one of the topics of interests and it is new in designing of rotating nano-systems. In this paper, the scale-dependent vibration analysis of a nanoplate with consideration of the axial force due to the rotation has been investigated. The governing equation and boundary conditions are derived using the Hamilton’s principle based on nonlocal elasticity theory. The boundary conditions of the nanoplate are considered as free-free in y direction and two clamped-free (cantilever plate) and clamped-simply (propped cantilever) in x direction. The equations have been solved using differential quadrature method to determine natural frequencies of the rotating nanoplate. For validation, in special cases, it has been shown that the obtained results coincide with literatures. The effects of the nonlocal parameter, aspect ratio, hub radius, angular velocity and different boundary conditions on the first three frequencies have been investigated. Results show that vibration behavior of the rotating nanoplate with cantilever boundary condition is different from other boundary conditions. تفاصيل المقالة -
حرية الوصول المقاله
11 - Vibration Analysis of Orthotropic Triangular Nanoplates Using Nonlocal Elasticity Theory and Galerkin Method
A.R Shahidi S.H Shahidi A Anjomshoae E Raeisi EstabraghIn this article, classical plate theory (CPT) is reformulated using the nonlocal differential constitutive relations of Eringen to develop an equivalent continuum model for orthotropic triangular nanoplates. The equations of motion are derived and the Galerkin’s a أکثرIn this article, classical plate theory (CPT) is reformulated using the nonlocal differential constitutive relations of Eringen to develop an equivalent continuum model for orthotropic triangular nanoplates. The equations of motion are derived and the Galerkin’s approach in conjunction with the area coordinates is used as a basis for the solution. Nonlocal theories are employed to bring out the effect of the small scale on natural frequencies of nano scaled plates. Effect of nonlocal parameter, lengths of the nanoplate, aspect ratio, mode number, material properties, boundary condition and in-plane loads on the natural frequencies are investigated. It is shown that the natural frequencies depend highly on the non-locality of the nanoplate, especially at the very small dimensions, higher mode numbers and stiffer edge condition. تفاصيل المقالة -
حرية الوصول المقاله
12 - Thermo-Mechanical Vibration Analysis of FG Circular and Annular Nanoplate Based on the Visco-Pasternak Foundation
M Goodarzi M Mohammadi M Khooran F SaadiIn this study, the vibration behavior of functional graded (FG) circular and annular nanoplate embedded in a Visco-Pasternak foundation and coupled with temperature change is studied. The effect of in-plane pre-load and temperature change are investigated on the vibrati أکثرIn this study, the vibration behavior of functional graded (FG) circular and annular nanoplate embedded in a Visco-Pasternak foundation and coupled with temperature change is studied. The effect of in-plane pre-load and temperature change are investigated on the vibration frequencies of FG circular and annular nanoplate. To obtain the vibration frequencies of the FG circular and annular nanoplate, two different size dependent theories are utilized. The material properties of the FGM nanoplates are assumed to vary in the thickness direction and are estimated through the Mori–Tanaka homogenization technique. The FG circular and annular nanoplate is coupled by an enclosing viscoelastic medium which is simulated as a Visco- Pasternak foundation. By using the modified strain gradient theory (MSGT) and the modified couple stress theory (MCST), the governing equation is derived for FG circular and annular nanoplate. The differential quadrature method (DQM) and the Galerkin method (GM) are utilized to solve the governing equation to obtain the frequency vibration of FG circular and annular nanoplate. The results are subsequently compared with valid result reported in the literature. The effects of the size dependent, the in-plane pre-load, the temperature change, the power index parameter, the elastic medium and the boundary conditions on the natural frequencies are investigated. The results show that the size dependent parameter has an increasing effect on the vibration response of circular and annular nanoplate. The temperature change also play an important role in the mechanical behavior of the FG circular and annular nanoplate. The present analysis results can be used for the design of the next generation of nanodevices that make use of the thermal vibration properties of the nanoplate تفاصيل المقالة -
حرية الوصول المقاله
13 - ساخت الکترودهای ابرخازنیِ نیکل منگنز اکسید (NiMnO3) نانوصفحهای با استفاده از روش سنتز هیدروترمال
سیدعلی حسینی مرادی نادر قبادی مجید امیرزادهاستفاده از سیستمهای ذخیره انرژی دوستدار محیط زیست به عنوان بهترین راهحل برای کاهش اثرات مضر سوختهای فسیلی شناخته شده است. ابرخازنها به دلیل داشتن دانسیته توان بالا، پایداری چرخه ای زیاد و دانسیته انرژی مطلوب بیش از دیگر سیستمها (باتری و پیلهای سوختی) در سالهای اخ أکثراستفاده از سیستمهای ذخیره انرژی دوستدار محیط زیست به عنوان بهترین راهحل برای کاهش اثرات مضر سوختهای فسیلی شناخته شده است. ابرخازنها به دلیل داشتن دانسیته توان بالا، پایداری چرخه ای زیاد و دانسیته انرژی مطلوب بیش از دیگر سیستمها (باتری و پیلهای سوختی) در سالهای اخیر مورد توجه قرار گرفتهاند. استفاده از مواد الکترودی ارزان قیمت و در دسترس، کلید توسعه ابرخازن ها در مقیاس-های صنعتی و تجاری است. اکسیدهای نیکل و منگنز علاوه بر اینکه ارزان و در درسترس هستند، دارای ظرفیت ویژه تئوری بالایی هستند. با استفاده از این دو فلز در کنار هم میتوان به یک نوع مورفولوژی با سایتهای فعال الکتروشیمیایی زیاد دست یافت. در این پژوهش، ماده الکترودی نیکل منگنز اکسید (NiMnO3) با استفاده از روش هیدروترمال سنتز شد. سپس تستهای مشخصهیابی XRD، FT-IR و SEM جهت تعیین خواص کریستالوگرافیکی و مورفولوژیکی مورد استفاده قرار گرفتند. تستهای مشخصهیابی نشان دادند که که ذرات رومبوهدرال NiMnO3 با ساختار مزو حفرهای به دست آمدند. این ساختار مزوحفرهای ناشی از اتصال غیر یکنواخت نانوصفحات NiMnO3 به یکدیگر است. با انجام تستهای الکتروشیمیایی CV، GCD و EIS مشخص شد که الکترود NiMnO3دارای عملکرد عالی ابرخازنی با ظرفیت ویژه خازنی F/g 444 در دانسیته جریان A/g 1 است. این عملکرد مربوط به زیاد بودن و در دسترس بودن سایتهای فعال الکتروشمیایی الکترود NiMnO3 با مورفولوژی مناسب مزوحفرهای است که امکان انجام واکنشهای ذخیره بار را فراهم میکند. تفاصيل المقالة
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