External Electric Voltage Research Articles

Size-dependent free vibration and buckling analysis of magneto-electro-thermo-elastic nanoplates based on the third-order shear deformable nonlocal plate model

In this paper, a size-dependent nanoplate model is developed to describe the free vibration and buckling behaviors of magneto-electro-thermo-elastic (METE) rectangular nanoplates. It is assumed that the METE nanoplate is subjected to external electric voltage, external magnetic potential, and uniform temperature rise. The nonlocal elasticity theory along with the third-order shear deformation plate theory is employed for the size-dependent mathematical modeling of nanoplates. The presented model has two advantages over available models: (1) the need for the correction factor is bypassed and (2) it can be successfully applied to thick nanoplates. The governing equations and the corresponding boundary conditions are derived using the Hamilton’s principle which are then discretized on the space domain based on the generalized differential quadrature (GDQ) method. Afterward, an efficient numerical Galerkin procedure is adopted to reduce the discretized equations into Duffing-type ordinary differential equations. Numerical results are presented to examine the influences of nonlocal parameter, length-to-thickness ratio, temperature rise, external electric potential, external magnetic potential and type of boundary condition on the free vibration, and buckling behaviors of METE nanoplates. It is revealed that frequency and critical buckling load of nanoplates are dependent on magneto-electro-mechanical loadings, whereas they are less dependent on thermal loading.

Free vibration of a piezoelectric semiconductor plate

We analyze free vibration of a piezoelectric semiconductor (PSC) plate taking account of the coupling between deformation, polarization and carriers within the framework of the first-order shear deformation theory. The PSC plate is subjected to a biaxial force and an external electric voltage. The governing equations and corresponding boundary conditions are derived using Hamilton principle. An analytical solution for a simply supported PSC plate is obtained. A detailed parametric study is conducted to discuss the effects of steady-state carrier density, axial force, external electric voltage, length-to-thickness ratio and length-to-width ratio on the free vibration characteristics of the PSC plate. The numerical results show that the steady-state carrier density has a significantly influence on natural frequency of the PSC plate in a certain range. The vibration frequency decreases when the plate is subjected to the axial compression and the positive external voltage. The vibration frequency increases with the increase of length-width ratio of and also increases with the decrease of length-thickness ratio of the PSC plate. This work may be useful for the analysis and design of electron devices made from PSC materials.

Selection of size dependency theory effects on the wave's dispersions of magneto-electro-thermo-elastic nano-beam resting on visco-elastic foundation

Current research develops a comprehensive wave propagation analysis of a magneto-electro-thermo-elastic (METE) nano-beam (NB) resting on the visco-elastic medium. To model the size dependency effects, modified couple stress (MCS) and Eringen's nonlocal (ENL) theories are employed to analyze and describe the wave propagation behaviors for those nano-beams. These theories were the most used in the literature due to the inclusion of one additional size-dependent length scale parameter. Those theories are compared side by side in this investigation and their impacts/differences on the wave propagation of specific materials are explored. Sinusoidal shear deformation beam model with Hamilton's principle is adopted to develop the governing equations of motion. Then, an analytical solution is executed to extract numerical results for transverse wave propagation in both elastic and METE configurations of the nano-beam. The effects of size-dependent length scale of both theories, thickness of NB, Winkler-Pasternak coefficients, thermal gradient, and magnetic potential and external electric voltage are illustrated and discussed in details. It is concluded that wave frequency decreases with increment of nonlocal parameter for ENL model. On the other hand, a stiffening effect takes place for the wave frequency when the MCS model is considered. Hence, the results indicate that there is a significant difference between ENL and MCS theories in the estimation of the behavior of wave propagation in small-scale structures. One of the main results of this investigation indicates that the MCS theory has similar nonlocal effects as the Eringen's theory for specific conditions.

Electro-thermal buckling of FG graphene platelets-strengthened piezoelectric beams under humid conditions

In this article, thermal buckling analysis of multilayer functionally graded graphene platelets (FGGPL) strengthened piezoelectric beam subjected to external electric voltage as well as humid conditions is illustrated. The effective Young’s modulus of the nanocomposite beam is estimated within the framework of Halpin-Tsai model. While, Poisson’s ratio, mass density, and piezoelectric properties are calculated by the rule of the mixture. Four FGGPL distribution types are considered in this study. A refined two-unknown beam theory considering shear deformation as well as thickness stretching effect is employed to describe the displacement components. The principle of virtual work including thermal, moisture, and electric loads is used to derive the stability differential equations. To check the accuracy of the obtained buckling temperature, some comparison examples are performed. The impacts of the GPLs volume fraction, distribution type, length-to-depth ratio, humid conditions, external electric voltage, and piezoelectric properties on the critical buckling temperature are studied.

Polarized Hydroxyapatite: New Insights and Future Perspectives Through Systematic Electrical Characterization at the Interface

AbstractDesign of hydroxyapatite (HAp) with customized electrical properties is of special interest for developing technological and biomedical applications with new improved functionalities. Polarized HAp, which is obtained by applying an external electric voltage at high temperature, has been successfully shown to be an alternative to doped‐HAp that is limited by the biocompatibility of the dopants used. However, many aspects about such new material remain scarcely studied, as for example the relationship between the polarization conditions and the resultant electrical enhancement, hinder a solid progress in its application. In this work, polarized HAp has been extensively characterized using electrochemical impedance spectroscopy by means of proposing a unified electrical equivalent circuit model with physical sense. This allows to explain the properties of such material by separating the bulk and the interface contributions. Moreover, the limits of the polarization mechanism have been explored, enabling a precise control on the electrical resistivity of polarized HAp above or below the intrinsic resistivity of nonpolarized HAp. Overall, necessary insights on the polarization treatment have been reported, opening an appealing avenue for generating new biomedical and technological applications based on dopant‐free polarized HAp.

Two phase local/non local waves in a magneto thermo electrical composite nano beam reinforced with graphene oxide powder

The present article studies the two phase local/nonlocal deformation of magneto thermo electrical composite nano beam reinforced with graphene oxide powder (GOP). The controlling equation of motion and boundary conditions are derived via two phase elasticity in differential form conjunction with Hamilton’s principle and Euler-Bernoulli beam model. The effect of a non-uniform magnetic and piezo electric field is incorporated with the governing equations by convoluting field quantities and displacement components. Then, Navier method is adopted to observe the influence of various boundary conditions on the dynamics of the beam. Comparison studies are performed to display the accuracy and efficiency of this analytical model. Further, the effects of magnetic field, GOP weight fraction, two phase parameter, external electric voltage, nonlocal parameter and temperature difference on the dimensionless frequency of GOP reinforced magneto piezo thermo elastic composite beams are thoroughly investigated and highlighted through tables and dispersion curves.

Analytical buckling temperature prediction of FG piezoelectric sandwich plates with lightweight core

Buckling temperature prediction of a functionally graded piezoelectric (FGP) sandwich plate with lightweight core is studied in the present work. The composite plate is made of three layers. The upper and lower layers are made of two different piezoelectric materials so that the electrical and mechanical properties are smoothly varied through the thickness based on a power law distribution. Whereas, the lightweight core is considered as hexagonal honeycomb structure or functionally graded porous structure. The porous core contains internal pores with different porosity distributions. According to a modified four-unknown shear deformation plate theory, the displacement field is described. The smart advanced plate is subjected to thermal and humid loadings as well as external electric voltage. The thermal and humid loadings may be uniform, linear or non-linear through the thickness. The stability equations are constructed from the principle of virtual work based on the proposed shear deformation plate theory. The obtained results will be validated by introducing some comparison examples. Finally, the influences of different parameters like the side-to-thickness ratio, aspect ratio, core type, core thickness, power law index, moisture concentration, external applied voltage and boundary conditions on the buckling temperature change of the sandwich plates with honeycomb core or with porous core are discussed. It is found that the buckling temperature of the sandwich plate with honeycomb core is greater than that of the sandwich plate with porous core. Moreover, with increasing the lightweight core thickness, the sandwich plate stiffness decreases leading to a reduction of the buckling temperature.

Dynamical manipulation of a dual-polarization plasmon-induced transparency employing an anisotropic graphene-black phosphorus heterostructure.

Dynamical tunable plasmon-induced transparency (PIT) possesses the unique characteristics of controlling light propagation states, which promises numerous potential applications in efficient optical signal processing chips and nonlinear optical devices. However, previously reported configurations are sensitive to polarization and can merely operate under specific single polarization. In this work we propose an anisotropic PIT metamaterial device based on a graphene-black phosphorus (G-BP) heterostructure to realize a dual-polarization tunable PIT effect. The destructive interference coupling between the bright mode and dark modes under the orthogonal polarization state pronounced anisotropic PIT phenomenon. The coupling strength of the PIT system can be modulated by dynamically manipulating the Fermi energy of the graphene via the external electric field voltage. Moreover, the three-level plasmonic system and the coupled oscillator model are employed to explain the underlying mechanism of the PIT effect, and the analytical results show good consistency with the numerical calculations. Compared to the single-polarization PIT devices, the proposed device offers additional degrees of freedom in realizing universal tunable functionalities, which could significantly promote the development of next-generation integrated optical processing chips, optical modulation and slow light devices.

Response Suppression of FGM Plate Using Piezoelectric Layers Under Parametric Uncertainty Conditions with Markovian Jump Approach

It should be noted that in addition to the geometry, constituent material also affects the strength and rigidity of the cylindrical shell, some factors that determine the transient response are its geometry and the constituent material. The capability of piezoelectric materials to adept their properties in reaction to environmental factors including electricity and loading is one of the major reasons for using in this work. Therefore, in this study, the transient response of a symmetric annular sandwich plate incorporating functionally graded core and piezoelectric layers under external harmonic force and electrical voltage is investigated. The properties of the core material vary along its thickness according to a power law model. The displacement field is represented by the third-order shear deformation theory. With the aid of Hamilton’s principle, the structural equations are obtained in terms of displacement components, then solved using the differential quadrature method. In addition, the time response is evaluated with respect to effective parameters including the internal radius, power law index, core thickness, and external voltage. According to the simulation results, the oscillation amplitude decreases as the internal radius of the plate increases over the desired time interval. Also, a higher index parameter is associated with a wider time response range. Moreover, the stability analysis of a piezoelectric system with [Formula: see text] performance is considered based on the theory of Markovian jump systems. To this end, a Markovian jump state-space model of the piezoelectric system obtained using system identification under the effect of external disturbance is presented. The [Formula: see text] stability index is selected based on a candidate Lyapunov function that leads to a set of linear matrix inequalities for each region. The uncontrolled and controlled transient responses of the coupled system under external disturbance are calculated and compared, indicating the satisfactory controller performance in the presence of external disturbance and jump in the sensor and system dynamics.

Electrostatic Circular Membrane MEMS: An Approach to the Optimal Control

The recovery of the membrane profile of an electrostatic micro-electro-mechanical system (MEMS) is an important issue, because, when an external electrical voltage is applied, the membrane deforms with the risk of touching the upper plate of the device producing an unwanted electrostatic effect. Therefore, it is important to know whether the movement admits stable equilibrium configurations especially when the membrane is closed to the upper plate. In this framework, this work analyzes the behavior of a two-dimensional (2D) electrostatic circular membrane MEMS device subjected to an external voltage. Specifically, starting from a well-known 2D non-linear second-order differential model in which the electrostatic field in the device is proportional to the mean curvature of the membrane, the stability of the only possible equilibrium configuration is studied. Furthermore, when considering that the membrane is equipped with mechanical inertia and that it must not touch the upper plate of the device, a useful range of possible values has been obtained for the applied voltage. Finally, the paper concludes with some computations regarding the variation of potential energy, identifying some optimal control conditions.

On the piezoelectric effect on stability of symmetric FGM porous nanobeams

In present paper, the piezoelectric effect on bifurcation buckling of symmetric FGM porous nanobeam is presented based on a higher-order nonlocal elasticity and strain gradient theory in conjunction with Reddy third-order shear deformation beam theory. The strain energy density and electric enthalpy density functions are used to derive constitutive relations for porous functionally graded, as well as piezoelectric materials. Equations of motion for elastically supported layered FGM nanobeam with diverse distribution of porosity and electro-elastic coupling are derived based on the modified Hamilton’s variational principle. The formulated boundary value problem is analytically solved. For the first time, the effects of porosity distribution, volume of voids, distance between porosity and FGM core surfaces as well as material gradation, layers size, aspect ratio, stiffness of Kerr foundation, and external electric voltage on critical in-plane force, critical porosity and critical voltage were comprehensively presented and discussed. The investigation enables analysis and precise multi-dimensional control of static response of smart beam-like nanostructures widely used in MEMS and NEMS devices.

Investigation of the Nonstationary Stochastic Response of Functionally Graded Piezoelectric Material Plates with General Boundary Conditions

The functionally graded piezoelectric material (FGPM) has been widely used in various engineering cases due to its excellent mechanical properties. So far, the investigations on the stochastic dynamic behaviors of FGPM structures are few. This paper develops a unified solution for the nonstationary stochastic responses of the FGPM plate with general boundary conditions, in which the point, distributed and base acceleration random excitations can be considered. The first-order shear deformation theory (FSDT) is adopted to formulate the energy functional of the system and the governing equations are deduced by using the Hamilton's principle. The solutions of the system are obtained based on the modified Ritz method and pseudo excitation method (PEM). The accuracy of the proposed model is validated by comparing the obtained free vibration and random response results with those from the published literature. Finally, the effects of key parameters including boundary conditions, external electric voltage, material constituent and time modulated function on the stochastic response of the FGPM plate are investigated.

Electro-optic lithium niobate metasurfaces

Many applications of metasurfaces require an ability to dynamically change their properties in the time domain. Electrical tuning techniques are of particular interest, since they pave a way to on-chip integration of metasurfaces with optoelectronic devices. In this work, we propose and experimentally demonstrate an electro-optic lithium niobate (EO-LN) metasurface that shows dynamic modulations to phase retardation of transmitted light. Quasi-bound states in the continuum (QBIC) are observed from this metasurface. By applying external electric voltages, the refractive index of lithium niobate (LN) is changed by Pockels EO nonlinearity, leading to efficient phase modulations to the transmitted light around the QBIC wavelength. The EO-LN metasurface developed in this study opens up new routes for potential applications in the field of displaying, pulse shaping, and spatial light modulating.

Thermo-electro-mechanical vibration and buckling analysis of quadrilateral and triangular nanoplates with the nonlocal finite strip method

As a first endeavor, thermo-electro-mechanical analysis of quadrilateral and triangular piezoelectric nanoplates are investigated based on the nonlocal theory and the Kirchhoff plate theory. It is assumed that the piezoelectric nanoplate is subjected to a biaxial force, an external electric voltage, and a uniform temperature rise. Hamilton’s principle is employed to derive the governing equations. The B3-spline finite strip method used to determine the natural frequencies, buckling loads, and corresponding mode shapes of displacement and the electric potential of quadrilateral and triangular piezoelectric nanoplates, for the first time. The comprehensive parametric study is conducted to explore the effect of the nonlocal parameter, geometrical shape, thermo-electro-mechanical loadings, boundary conditions, aspect ratio, and side length. It is shown that small-scale effect plays a considerable role in the buckling and vibration behavior of quadrilateral and triangular piezoelectric nanoplates.

Wave propagation in a non-local piezoelectric phononic crystal Timoshenko nanobeam

By applying non-local elasticity theory and plane wave expansion (PWE) method to Timoshenko beam, the calculation method of band structure of a non-local piezoelectric phononic crystal (PC) Timoshenko nanobeam is proposed and formulized. In order to investigate the properties of wave propagating in the nanobeam in detail, bandgaps of first four orders are picked, and the corresponding influence rules of thermo-electro-mechanical coupling fields, non-local effect and geometric parameters on bandgaps are studied. During the research works, temperature variation, external electrical voltage and axial force are chosen as the influencing parameters related to the thermo-electro-mechanical coupling fields. Scale coefficient is chosen as the influencing parameter corresponding to non-local effect. Length ratio between materials PZT-4 and epoxy and height-width ratio are chosen as the influencing parameters of geometric parameters. Moreover, all the band structures and influence rules of Timoshenko nanobeam are compared to those of Euler nanobeam. The results are expected to be of help for the design of micro and nanodevices based on piezoelectric periodic nanobeams.

Probing Luminescent Radiation of Positive Streamer in Atmospheric Air: Experiments at Low Temperature

A photo-charge measurement system based on large dynamic photomultiplier tube (PMT) and current integration method is set up to capture the transient optical signal generated by the positive streamer in the test chamber of which the temperature is adjustable. The results of the luminescent radiation, including the photo-charge quantity, propagation velocity and morphology of the streamer, for the three-electrode and the rod-plate electrode arrangements are presented at different temperatures. The influence trend of temperature on streamer is similar in both arrangements. The pronounced feature of luminescent radiation in the low temperature air ranging from 173 to 293 K is that it has a positive correlation with the temperature. The photo-charge amount of the uniform and non-uniform field increases approximately linearly with the increase of external electric field and voltage, respectively. It is remarkable that the streamer channels become much clearer and brighter with the increase of the temperature. Furthermore, the real luminescent radiation intensity of streamer and the feather-like structure were also displayed by the nanosecond resolved ICCD images.

Electroless Deposition of Ni-P Composite and Multilayer Coatings: Applications and Perspectives

Considerable economic losses occur every year due to erosion-corrosion in parts of machines and equipment during service. In order to reduce this loss, properties of the surface of the materials should be improved. Among the various surface processes, electroless plating is one of the appropriate methods to deposit coatings on metals without applying an external electrical voltage, which provides coatings with uniform thickness, crack free nature, appropriate adhesion to the substrate, high hardness, and high wear resistance. The electroless deposition is a promising method to prepare durable metal films on both conducting and non-conducting substrates of different geometries. In the present study, Ni-P composite coatings were successfully electroless plated on mild carbon steel from acidic baths reinforced with ceramic and polymeric micro and nano-particles, as single and multilayer deposits. The effect of the electrolyte composition as well as the nature of the dispersed phase on the phosphorus co-deposition, particles incorporation, surface morphology and structure of the deposits have been investigated and evaluated. The use of multilayer or hybrid techniques in surface engineering has often been cited as the way to improve the mechanical, tribological and electrochemical properties of coatings. Especially, the multilayer coating with layers having different corrosion potential Ecorr was an effective solution to improve the corrosion-resistance of the no-sacrificial coatings. Multilayered coatings were produced by stacking layers of different composition by successive electroless plating with rinsing steps in between. This study will discuss new applications and perspectives of these coatings as anti erosion-corrosion surface treatments. The impact of the plating approach on the microstructure of the coatings as well as on their mechanical properties and corrosion resistance is presented.

Design of Multifunctional Composites: New Strategy to Save Energy and Improve Mechanical Performance.

In this paper, an alternative curing strategy, based on the application of an electric field, is proposed to harden nano-filled multifunctional resins. The resin is obtained through the dispersion of carbon nanotubes, which act as nanometric heater elements in the epoxy matrix. The electro-curing is activated by applying an external electric voltage, which allows tunable cross-linking within the epoxy matrix entrapped between the nanotubes. The electro-curing method allows reaching higher curing degrees with respect to the conventional ones and, consequently, higher glass transition temperatures. This is a direct consequence of the fact that the curing reactions start directly in the regions at the interphase between carbon nanotubes, acting as heater nano-filaments, and the polymeric matrix. The proposed method is able to give composites better properties, making the curing process fast and energy-saving.

Buckling analysis of actuated functionally graded piezoelectric plates via a quasi-3D refined theory

The electro-mechanical buckling response for functionally graded piezoelectric plates subjected to external electric voltage is analyzed based on a quasi-3D refined plate theory. The plate material properties possess continuous graded variation across the thickness based on the power-law form. The total potential energy principle is used to obtain the equilibrium equations. Navier's procedure is applied to derive the solution for the buckling of a simply supported functionally graded piezoelectric plate. A numerical example is presented to validate the accuracy of the present analysis. The critical buckling of actuated FGP plates is determined. The influence of external electric voltage, the geometry of the plate, and material exponent on the critical buckling are reported.

Doubly electrically tuned cylindrical Bragg fiber waveguide inline optical filter for multiwavelength LASER applications

In present communication, doubly tuned Bragg fiber waveguide low power inline optical filter with voltage tunable single crystal PMMA defect cavity is theoretically modeled and discussed using Henkel formalism in a cylindrical coordinate system for multiwavelength LASER applications. The structure provides photonic band gap (PBG) with a resonant transmission peak in the obtained PBG region. The defect cavity thickness is controlled by applying an external electric DC voltage. Initially, PBG of the proposed inline optical filter may tune-up to 828nm by modulating the incidence angle upto 80°. Thus, the resonant transmission peak also blue-shifted by 243nm, which can further tuned in presence of DC voltages and so-called doubly electrically tuned. Further, in doubly electrically tuned mode, the application range of such a device is very large up to 129nm for a small change in voltage range about 20V. Thus, the present device can be utilized as multiwavelength laser sources.