Pub Date : 2017-09-25DOI: 10.1177/2397791417731452
Thirupathi Thumma, O. Bég, S. Sheri
This work describes finite element computations for radiative magnetohydrodynamic convective Newtonian nanofluid flow from an oscillating inclined porous plate with variable temperature. Heat source/sink and buoyancy effects are included in the mathematical model. The problem is formulated by employing Tiwari–Das nanofluid model, and two water-based nanofluids, copper and alumina, with spherical shaped metal nanoparticles are considered. The Brinkman and Maxwell–Garnetts models are used for the dynamic viscosity and effective thermal conductivity of the nanofluids, respectively. An algebraic flux model, the Rosseland diffusion approximation, is adopted to simulate thermal radiative flux effects. The dimensionless, coupled governing partial differential equations are numerically solved via the finite element method with weak variational formulation by imposing initial and boundary conditions with a weighted residual scheme. A grid independence study is also conducted. The finite element solutions are reduced to known previous solutions in some limiting cases of this investigation and are found to be in good agreement with published work. This investigation is relevant to electromagnetic nano-material manufacturing processes operating at high temperatures where radiation heat transfer is significant.
{"title":"Finite element computation of magnetohydrodynamic nanofluid convection from an oscillating inclined plate with radiative flux, heat source and variable temperature effects","authors":"Thirupathi Thumma, O. Bég, S. Sheri","doi":"10.1177/2397791417731452","DOIUrl":"https://doi.org/10.1177/2397791417731452","url":null,"abstract":"This work describes finite element computations for radiative magnetohydrodynamic convective Newtonian nanofluid flow from an oscillating inclined porous plate with variable temperature. Heat source/sink and buoyancy effects are included in the mathematical model. The problem is formulated by employing Tiwari–Das nanofluid model, and two water-based nanofluids, copper and alumina, with spherical shaped metal nanoparticles are considered. The Brinkman and Maxwell–Garnetts models are used for the dynamic viscosity and effective thermal conductivity of the nanofluids, respectively. An algebraic flux model, the Rosseland diffusion approximation, is adopted to simulate thermal radiative flux effects. The dimensionless, coupled governing partial differential equations are numerically solved via the finite element method with weak variational formulation by imposing initial and boundary conditions with a weighted residual scheme. A grid independence study is also conducted. The finite element solutions are reduced to known previous solutions in some limiting cases of this investigation and are found to be in good agreement with published work. This investigation is relevant to electromagnetic nano-material manufacturing processes operating at high temperatures where radiation heat transfer is significant.","PeriodicalId":44789,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers Part N-Journal of Nanomaterials Nanoengineering and Nanosystems","volume":null,"pages":null},"PeriodicalIF":6.0,"publicationDate":"2017-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76500948","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-09-15DOI: 10.1177/2397791417731025
F. J. Kadhim, A. Anber
In this work, high-quality nanostructured silicon nitride films were prepared by reactive direct current magnetron sputtering technique. The properties of the prepared structures were determined by the ratios of gases (argon and nitrogen) in the discharge gas mixture. This parameter was effectively seen important to control the structural characteristics of the prepared nanostructures, especially surface roughness and particle size. The prepared nanostructures were successfully tested for gas-sensing applications and they exhibited reasonably high sensitivity for their resistance changes to gas concentration with increasing temperature (up to 96% at 350 °C). This work can be good attempt to use silicon nitride nanostructures in such important application.
{"title":"Fabrication of nanostructured silicon nitride thin film gas sensors by reactive direct current magnetron sputtering","authors":"F. J. Kadhim, A. Anber","doi":"10.1177/2397791417731025","DOIUrl":"https://doi.org/10.1177/2397791417731025","url":null,"abstract":"In this work, high-quality nanostructured silicon nitride films were prepared by reactive direct current magnetron sputtering technique. The properties of the prepared structures were determined by the ratios of gases (argon and nitrogen) in the discharge gas mixture. This parameter was effectively seen important to control the structural characteristics of the prepared nanostructures, especially surface roughness and particle size. The prepared nanostructures were successfully tested for gas-sensing applications and they exhibited reasonably high sensitivity for their resistance changes to gas concentration with increasing temperature (up to 96% at 350 °C). This work can be good attempt to use silicon nitride nanostructures in such important application.","PeriodicalId":44789,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers Part N-Journal of Nanomaterials Nanoengineering and Nanosystems","volume":null,"pages":null},"PeriodicalIF":6.0,"publicationDate":"2017-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86929811","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-08-03DOI: 10.1177/2397791417719970
M. Karimi, A. Shahidi
In this article, the influence of temperature change on the vibration, buckling, and bending of orthotropic graphene sheets embedded in elastic media including surface energy and small-scale effects is investigated. To take into account the small-scale and surface energy effects, the nonlocal constitutive relations of Eringen and surface elasticity theory of Gurtin and Murdoch are used, respectively. Using Hamilton’s principle, the governing equations for bulk and surface of orthotropic nanoplate are derived using two-variable refined plate theory. Finite difference method is used to solve governing equations. The obtained results are verified with Navier’s method and validated results reported in the literature. The results demonstrated that for both isotropic and orthotropic material properties, by increasing the temperature changes, the degree of surface effects on the buckling and vibration of nanoplates could enhance at higher temperatures, while it would diminish at lower temperatures. In addition, the effects of surface and temperature changes on the buckling and vibration for isotropic material property are more noticeable than those of orthotropic. On the contrary, these results are totally reverse for bending problem.
{"title":"Thermo-mechanical vibration, buckling, and bending of orthotropic graphene sheets based on nonlocal two-variable refined plate theory using finite difference method considering surface energy effects","authors":"M. Karimi, A. Shahidi","doi":"10.1177/2397791417719970","DOIUrl":"https://doi.org/10.1177/2397791417719970","url":null,"abstract":"In this article, the influence of temperature change on the vibration, buckling, and bending of orthotropic graphene sheets embedded in elastic media including surface energy and small-scale effects is investigated. To take into account the small-scale and surface energy effects, the nonlocal constitutive relations of Eringen and surface elasticity theory of Gurtin and Murdoch are used, respectively. Using Hamilton’s principle, the governing equations for bulk and surface of orthotropic nanoplate are derived using two-variable refined plate theory. Finite difference method is used to solve governing equations. The obtained results are verified with Navier’s method and validated results reported in the literature. The results demonstrated that for both isotropic and orthotropic material properties, by increasing the temperature changes, the degree of surface effects on the buckling and vibration of nanoplates could enhance at higher temperatures, while it would diminish at lower temperatures. In addition, the effects of surface and temperature changes on the buckling and vibration for isotropic material property are more noticeable than those of orthotropic. On the contrary, these results are totally reverse for bending problem.","PeriodicalId":44789,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers Part N-Journal of Nanomaterials Nanoengineering and Nanosystems","volume":null,"pages":null},"PeriodicalIF":6.0,"publicationDate":"2017-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78935374","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-06-21DOI: 10.1177/2397791417712836
K. Singh, S. Chaudhary, R. Venugopal, A. Gaurav
This work proposes the production of multi-walled carbon nanotubes by AC arc discharging of spectroscopically pure graphite electrodes of different shapes, that is, movable cylindrical and stationary rectangular electrode by manual metal arc welding setup. Continuous arc was generated by maintaining the gap of about 3 mm between the electrodes which in turn formed the plasma zone. Vaporization of carbon cations followed by sudden quenching paved the way for formation of carbon nantotubes. Nanotubes produced were deposited on the stationary graphite electrode in the form of soot. Further extraction of the nanoparticles from the soot was performed by conducting series of purification processes which will be discussed in upcoming chapters. Morphology and purity of the extracted nanotubes were investigated by X-ray diffraction, scanning electron microscopy, field-emission scanning electron microscopy, transmission electron microscopy and Raman spectroscopy. Following the characterization process, it was observed that the so-produced nanotubes were of different shapes, that is, carbon cone nanotubes, nanocapsules, nanoparticles and branching type and randomly oriented. The length of the nanotubes varied from 231 to 561 nm, whereas diameter was found to be in the range of 14–55 nm.
{"title":"Bulk synthesis of multi-walled carbon nanotubes by AC arc discharge method","authors":"K. Singh, S. Chaudhary, R. Venugopal, A. Gaurav","doi":"10.1177/2397791417712836","DOIUrl":"https://doi.org/10.1177/2397791417712836","url":null,"abstract":"This work proposes the production of multi-walled carbon nanotubes by AC arc discharging of spectroscopically pure graphite electrodes of different shapes, that is, movable cylindrical and stationary rectangular electrode by manual metal arc welding setup. Continuous arc was generated by maintaining the gap of about 3 mm between the electrodes which in turn formed the plasma zone. Vaporization of carbon cations followed by sudden quenching paved the way for formation of carbon nantotubes. Nanotubes produced were deposited on the stationary graphite electrode in the form of soot. Further extraction of the nanoparticles from the soot was performed by conducting series of purification processes which will be discussed in upcoming chapters. Morphology and purity of the extracted nanotubes were investigated by X-ray diffraction, scanning electron microscopy, field-emission scanning electron microscopy, transmission electron microscopy and Raman spectroscopy. Following the characterization process, it was observed that the so-produced nanotubes were of different shapes, that is, carbon cone nanotubes, nanocapsules, nanoparticles and branching type and randomly oriented. The length of the nanotubes varied from 231 to 561 nm, whereas diameter was found to be in the range of 14–55 nm.","PeriodicalId":44789,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers Part N-Journal of Nanomaterials Nanoengineering and Nanosystems","volume":null,"pages":null},"PeriodicalIF":6.0,"publicationDate":"2017-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76748672","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-06-16DOI: 10.1177/2397791417712851
A Ghorbanpour Arani, E. Haghparast, Z. K. Maraghi
In this research, orthotropic Euler–Bernoulli beam and Timoshenko beam models are developed to investigate vibrational behavior of coupled protein microtubules. Microtubules are hollow cylindrical filaments in the living cells which are surrounded by filament network, which is simulated by Winkler–Riley Model. Temperature-dependent material properties for microtubules are used to study the thermal effect on vibration frequency. To apply the size effect, nonlocal theory is utilized, and the motion equations are derived based on Hamilton’s principle. In order to examine reliability of presented study, effects of various parameters such as environmental conditions, temperature change, boundary conditions and small-scale parameters on vibration characteristics of isotropic and orthotropic microtubules for both Euler–Bernoulli beam and Timoshenko beam models are discussed in detail. Results revealed that dynamic behavior of coupled microtubules is strongly dependent on the surface elasticity modulus of cytosol, so that, increasing surface elasticity modulus leads to increase in frequency of coupled microtubules. Results of this investigation can be provided as a useful reference in bio-medical clinical application.
{"title":"Vibrational response of coupled orthotropic protein microtubules immersed in cytosol considering small-scale and surface effects","authors":"A Ghorbanpour Arani, E. Haghparast, Z. K. Maraghi","doi":"10.1177/2397791417712851","DOIUrl":"https://doi.org/10.1177/2397791417712851","url":null,"abstract":"In this research, orthotropic Euler–Bernoulli beam and Timoshenko beam models are developed to investigate vibrational behavior of coupled protein microtubules. Microtubules are hollow cylindrical filaments in the living cells which are surrounded by filament network, which is simulated by Winkler–Riley Model. Temperature-dependent material properties for microtubules are used to study the thermal effect on vibration frequency. To apply the size effect, nonlocal theory is utilized, and the motion equations are derived based on Hamilton’s principle. In order to examine reliability of presented study, effects of various parameters such as environmental conditions, temperature change, boundary conditions and small-scale parameters on vibration characteristics of isotropic and orthotropic microtubules for both Euler–Bernoulli beam and Timoshenko beam models are discussed in detail. Results revealed that dynamic behavior of coupled microtubules is strongly dependent on the surface elasticity modulus of cytosol, so that, increasing surface elasticity modulus leads to increase in frequency of coupled microtubules. Results of this investigation can be provided as a useful reference in bio-medical clinical application.","PeriodicalId":44789,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers Part N-Journal of Nanomaterials Nanoengineering and Nanosystems","volume":null,"pages":null},"PeriodicalIF":6.0,"publicationDate":"2017-06-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83091630","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-06-01DOI: 10.1177/2397791417712856
Thirupathi Thumma, O. Bég, S. Sheri
This article aimed to investigate the transient dissipative magnetohydrodynamic double diffusive free convective boundary layer flow of electrically conducting nanofluids from a stationary or moving vertical porous surface in a rotating high permeability porous medium, considering buoyancy, thermal radiation and first-order chemical reaction. Thermo-diffusion (Soret) and diffuso-thermo (Dufour) effects are also considered. Darcy’s law is employed. The mathematical model is formulated by considering water-based nanofluids containing metallic nano-particles for both stationary and moving plate cases. Three nanofluids are examined, namely copper, aluminium oxide or titanium oxide in water. The transformed non-linear, coupled, dimensionless partial differential equations describing the flow are solved with physically appropriate boundary conditions using Galerkin weighted residual scheme. For prescribed permeability, numerical results are presented graphically for the influence of a number of emerging parameters. Validation of finite element solutions for skin friction and Nusselt number is achieved via comparison with the previously published work as special cases of the present investigation and very good correlation obtained. Increasing rotational parameter is observed to reduce both primary and secondary velocity components. Primary and secondary velocities are consistently elevated with increasing Soret, Dufour, thermal Grashof and solutal Grashof numbers. Increasing Schmidt number, chemical reaction and suction parameter both suppress nano-particle concentration whereas the converse behavior is computed with increasing Soret number. The study is relevant to high-temperature rotating chemical engineering systems exploiting magnetized nanofluids and also electromagnetic nanomaterial manufacturing processes.
{"title":"Finite element computation of transient dissipative double diffusive magneto-convective nanofluid flow from a rotating vertical porous surface in porous media","authors":"Thirupathi Thumma, O. Bég, S. Sheri","doi":"10.1177/2397791417712856","DOIUrl":"https://doi.org/10.1177/2397791417712856","url":null,"abstract":"This article aimed to investigate the transient dissipative magnetohydrodynamic double diffusive free convective boundary layer flow of electrically conducting nanofluids from a stationary or moving vertical porous surface in a rotating high permeability porous medium, considering buoyancy, thermal radiation and first-order chemical reaction. Thermo-diffusion (Soret) and diffuso-thermo (Dufour) effects are also considered. Darcy’s law is employed. The mathematical model is formulated by considering water-based nanofluids containing metallic nano-particles for both stationary and moving plate cases. Three nanofluids are examined, namely copper, aluminium oxide or titanium oxide in water. The transformed non-linear, coupled, dimensionless partial differential equations describing the flow are solved with physically appropriate boundary conditions using Galerkin weighted residual scheme. For prescribed permeability, numerical results are presented graphically for the influence of a number of emerging parameters. Validation of finite element solutions for skin friction and Nusselt number is achieved via comparison with the previously published work as special cases of the present investigation and very good correlation obtained. Increasing rotational parameter is observed to reduce both primary and secondary velocity components. Primary and secondary velocities are consistently elevated with increasing Soret, Dufour, thermal Grashof and solutal Grashof numbers. Increasing Schmidt number, chemical reaction and suction parameter both suppress nano-particle concentration whereas the converse behavior is computed with increasing Soret number. The study is relevant to high-temperature rotating chemical engineering systems exploiting magnetized nanofluids and also electromagnetic nanomaterial manufacturing processes.","PeriodicalId":44789,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers Part N-Journal of Nanomaterials Nanoengineering and Nanosystems","volume":null,"pages":null},"PeriodicalIF":6.0,"publicationDate":"2017-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80611558","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-06-01DOI: 10.1177/2397791417712870
A. Naderi, A. Saidi
This article reviews conventional nonlocal elasticity constitutive relation which is frequently used for mechanical analyses of nanostructures. It is shown here that since this constitutive relation has been essentially derived based on infinite-body assumption, it cannot consider the nonlocal effects at all points of a nanoscale body accurately. Also, it is shown that although the nonlocal constitutive relations can potentially consider the surface effects, that constitutive relation has been obtained substantially by ignoring those effects. So, it cannot also consider the surface effects accurately. Therefore, the conventional nonlocal constitutive relation generally is not accurate for material-behavior modeling and consequently mechanical analysis of nanostructures. Furthermore, common nonlocal constitutive law is examined in buckling problem of Timoshenko beam-columns to show another limitation of that constitutive law. Finally, some special cases for which that constitutive relation can be used more accurately are proposed.
{"title":"Common nonlocal elastic constitutive relation and material-behavior modeling of nanostructures","authors":"A. Naderi, A. Saidi","doi":"10.1177/2397791417712870","DOIUrl":"https://doi.org/10.1177/2397791417712870","url":null,"abstract":"This article reviews conventional nonlocal elasticity constitutive relation which is frequently used for mechanical analyses of nanostructures. It is shown here that since this constitutive relation has been essentially derived based on infinite-body assumption, it cannot consider the nonlocal effects at all points of a nanoscale body accurately. Also, it is shown that although the nonlocal constitutive relations can potentially consider the surface effects, that constitutive relation has been obtained substantially by ignoring those effects. So, it cannot also consider the surface effects accurately. Therefore, the conventional nonlocal constitutive relation generally is not accurate for material-behavior modeling and consequently mechanical analysis of nanostructures. Furthermore, common nonlocal constitutive law is examined in buckling problem of Timoshenko beam-columns to show another limitation of that constitutive law. Finally, some special cases for which that constitutive relation can be used more accurately are proposed.","PeriodicalId":44789,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers Part N-Journal of Nanomaterials Nanoengineering and Nanosystems","volume":null,"pages":null},"PeriodicalIF":6.0,"publicationDate":"2017-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83760691","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-06-01DOI: 10.1177/2397791417712845
G. Giannopoulos, Giorgos S Avntoulla
Graphene, the strongest known material, is significantly influenced by the loading conditions, the environmental temperature and the existence of internal imperfections and discontinuities such as cracks. Higher temperatures lead to higher atomic kinetic energies and easier failure of graphene while even a one atom vacancy may cause a dramatic reduction in its strength. The aim of the present study is to describe analytical expressions which associate the tensile strength of the monolayer graphene with the temperature and the length of a possible centrally positioned, straight crack. For this reason, molecular dynamics simulations are conducted to compute all the necessary numerical data. Then special equations are developed by fitting the computed data into appropriate non-linear regression surfaces. The proposed non-linear analytical equations are capable of straightforwardly predicting the strength of graphene given the chirality, the temperature and the size of the center crack under investigation.
{"title":"Tensile strength of graphene versus temperature and crack size: Analytical expressions from molecular dynamics simulation data","authors":"G. Giannopoulos, Giorgos S Avntoulla","doi":"10.1177/2397791417712845","DOIUrl":"https://doi.org/10.1177/2397791417712845","url":null,"abstract":"Graphene, the strongest known material, is significantly influenced by the loading conditions, the environmental temperature and the existence of internal imperfections and discontinuities such as cracks. Higher temperatures lead to higher atomic kinetic energies and easier failure of graphene while even a one atom vacancy may cause a dramatic reduction in its strength. The aim of the present study is to describe analytical expressions which associate the tensile strength of the monolayer graphene with the temperature and the length of a possible centrally positioned, straight crack. For this reason, molecular dynamics simulations are conducted to compute all the necessary numerical data. Then special equations are developed by fitting the computed data into appropriate non-linear regression surfaces. The proposed non-linear analytical equations are capable of straightforwardly predicting the strength of graphene given the chirality, the temperature and the size of the center crack under investigation.","PeriodicalId":44789,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers Part N-Journal of Nanomaterials Nanoengineering and Nanosystems","volume":null,"pages":null},"PeriodicalIF":6.0,"publicationDate":"2017-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83729722","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-06-01DOI: 10.1177/2397791417712872
M. Masoumi, M. Masoumi
In this article, the effects of some parameters, including rotary inertia, non-local parameter, and length-to-thickness ratio, on natural frequencies are studied for both classical and non-local theories. For Timoshenko beam, the equations of motion and the boundary conditions are derived from Hamilton’s principle and then non-local constitutive equations of Eringen are employed to altogether formulate the problem. Afterward, obtained governing equations are used to study the free vibrations of a Timoshenko’s simply supported nano-beam. And finally, the effects of above-mentioned parameters on estimated frequencies in classical and non-local elasticity theories are investigated. Results show that the discrepancy between the frequencies of higher-order vibration modes obtained from two theories increases and also significant reductions in natural frequencies occur when the rotary inertia is considered in the computations.
{"title":"Non-local vibration of simply supported nano-beams: Higher-order modes","authors":"M. Masoumi, M. Masoumi","doi":"10.1177/2397791417712872","DOIUrl":"https://doi.org/10.1177/2397791417712872","url":null,"abstract":"In this article, the effects of some parameters, including rotary inertia, non-local parameter, and length-to-thickness ratio, on natural frequencies are studied for both classical and non-local theories. For Timoshenko beam, the equations of motion and the boundary conditions are derived from Hamilton’s principle and then non-local constitutive equations of Eringen are employed to altogether formulate the problem. Afterward, obtained governing equations are used to study the free vibrations of a Timoshenko’s simply supported nano-beam. And finally, the effects of above-mentioned parameters on estimated frequencies in classical and non-local elasticity theories are investigated. Results show that the discrepancy between the frequencies of higher-order vibration modes obtained from two theories increases and also significant reductions in natural frequencies occur when the rotary inertia is considered in the computations.","PeriodicalId":44789,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers Part N-Journal of Nanomaterials Nanoengineering and Nanosystems","volume":null,"pages":null},"PeriodicalIF":6.0,"publicationDate":"2017-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77495521","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-03-01DOI: 10.1177/1740349915614046
A. Ghorbanpour Arani, M. Jamali, M. Mosayyebi, R. Kolahchi
Wave propagation analysis of a functionally graded carbon nanotubes reinforced piezoelectric composite (FG-CNTRPC) microplate is the major main of the present research. In order to present a realistic model, the material properties of the system are assumed viscoelastic and the Kelvin–Voigt model is applied. The viscoelastic FG-CNTRPC microplate is subjected to longitudinal magnetic and three-dimensional electric fields. The distribution of carbon nanotubes in FG-CNTRPC microplate is supposed as uniform distribution and surrounding circumference is simulated as Visco-Pasternak foundation. The original formulation of the quasi-three-dimensional sinusoidal shear deformation plate theory is here extended to the wave propagation analysis and the size effects are considered based on Eringen’s nonlocal theory. In order to calculate the dimensionless frequency, cut-off and escape frequencies analytical solution is applied. In this article, the influences of the volume fraction of carbon nanotubes, electro-magnetic fields and elastic medium on the dimensionless frequency of viscoelastic FG-CNTRPC microplate are investigated. Furthermore, the effect of small-scale parameter on the cut-off and escape frequencies of the system will be studied. Results demonstrate that the dimensionless cut-off and escape frequencies decrease with increasing the magnitude of small-scale parameter. In addition, the imposed magnetic field and external voltage are significant parameters for controlling wave propagation of the viscoelastic FG-CNTRPC microplate. Results of this investigation can be helpful for the study and design of composite systems based on smart control and sensor applications.
{"title":"Analytical modeling of wave propagation in viscoelastic functionally graded carbon nanotubes reinforced piezoelectric microplate under electro-magnetic field","authors":"A. Ghorbanpour Arani, M. Jamali, M. Mosayyebi, R. Kolahchi","doi":"10.1177/1740349915614046","DOIUrl":"https://doi.org/10.1177/1740349915614046","url":null,"abstract":"Wave propagation analysis of a functionally graded carbon nanotubes reinforced piezoelectric composite (FG-CNTRPC) microplate is the major main of the present research. In order to present a realistic model, the material properties of the system are assumed viscoelastic and the Kelvin–Voigt model is applied. The viscoelastic FG-CNTRPC microplate is subjected to longitudinal magnetic and three-dimensional electric fields. The distribution of carbon nanotubes in FG-CNTRPC microplate is supposed as uniform distribution and surrounding circumference is simulated as Visco-Pasternak foundation. The original formulation of the quasi-three-dimensional sinusoidal shear deformation plate theory is here extended to the wave propagation analysis and the size effects are considered based on Eringen’s nonlocal theory. In order to calculate the dimensionless frequency, cut-off and escape frequencies analytical solution is applied. In this article, the influences of the volume fraction of carbon nanotubes, electro-magnetic fields and elastic medium on the dimensionless frequency of viscoelastic FG-CNTRPC microplate are investigated. Furthermore, the effect of small-scale parameter on the cut-off and escape frequencies of the system will be studied. Results demonstrate that the dimensionless cut-off and escape frequencies decrease with increasing the magnitude of small-scale parameter. In addition, the imposed magnetic field and external voltage are significant parameters for controlling wave propagation of the viscoelastic FG-CNTRPC microplate. Results of this investigation can be helpful for the study and design of composite systems based on smart control and sensor applications.","PeriodicalId":44789,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers Part N-Journal of Nanomaterials Nanoengineering and Nanosystems","volume":null,"pages":null},"PeriodicalIF":6.0,"publicationDate":"2017-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74303453","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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