Electric Potential Components Research Articles

Mechanical Analysis of Functionally Graded Multilayered Two-Dimensional Decagonal Piezoelectric Quasicrystal Laminates with Imperfect Interfaces

Quasicrystals have a wide range of applications due to their unique multi-field coupling effects and distinctive physical and mechanical characteristics. In this paper, the static and dynamic problems of imperfectly bonded, multilayered, functionally graded, two-dimensional decagonal piezoelectric quasicrystal laminates under mixed boundary conditions are investigated. The state equations in a concise and compact matrix form can be expressed by using differential quadrature regional discrete point expansions in any layer of the laminate. This allows for the representation of displacement, stress, electric potential, and electric displacement components. Then, different imperfect interface conditions are introduced to characterize specific structural and electric contact properties at the bounding interfaces, which are further converted to the interface propagator matrix. Numerical examples are carried out to investigate the impact of varying interface compliances, load types, and functional gradient factors on the static bending and vibration phenomena of QC laminates. These results can be used as references to validate existing or future numerical work on QC laminates and could further guide the design of related QC laminate structures.

Association between the number of altered late potential criteria and increased arrhythmic risk in Brugada syndrome patients.

Brugada syndrome (BrS) is associated with abnormal electrophysiological properties at right ventricular epicardium, consisting of fragmented electrograms extending well beyond QRS termination. We aimed to evaluate the utility of signal-averaged electrocardiogram (SA-ECG) for the noninvasive assessment of late potentials (LP) and risk stratification of BrS patients. A prospective, observational, single-center study of BrS patients is submitted to SA-ECG with the determination of the total filtered QRS duration (fQRS), root mean square voltage of the 40ms terminal portion of the QRS (RMS40), and duration of the low-amplitude electric potential component of the terminal portion of the QRS (LAS40). LP were considered positive when above standard cut-offs: fQRS > 114ms, RMS40 < 20µV, and LAS40 > 38ms. The rates of malignant arrhythmic events (MAEs), defined as sudden death or appropriate shocks, were compared in relation to clinical characteristics and SA-ECG findings. A total of 106 BrS patients (mean age, 48 ± 12years, 67.9% male) were studied, 49% with type-1 spontaneous pattern and 81% asymptomatic. During a median follow up of 4.7years, 10 patients (7.1%) suffered MAEs, including 4 sudden deaths. The presence of LP was significantly associated with the arrhythmic risk, which increased with the number of altered LP criteria. In comparison to the patients who had none or 1 altered LP criterium, MAE risk was 4.7 times higher in those with 2 altered criteria and 9.4 times higher in those with 3 altered LP criteria. SA-ECG may be a useful tool for risk stratification in BrS. The presence of 2 or 3 abnormal LP criteria could identify a subset of asymptomatic patients at high risk of arrhythmic events.

Features of ion exchange between the electrodes in metal-ion batteries during discharge

The importance and relevance of the storage of electrical energy is confirmed by events in the world and trends in the development and use of various electrical energy systems, household appliances, computer equipment, communication devices, etc. In addition to the growth of the metal-ion battery markets, there are trends towards a search for metals that in the future will be inexpensive and will have characteristics required for storage systems. This paper considers ion exchange between the electrodes of metal-ion batteries whose charge carriers are metal ions, which diffuse in the process of discharge from the negative electrode to the positive one. A mathematical model was developed and tested. The model is based on a system of diffusion transport equations with the Nernst–Planck–Poisson potential equation replaced by an equivalent conductivity potential equation. Quasi-equilibrium regimes are considered. The entire working area consists of a pore electrode space and a neutral separator. The mathematical model employed consists of potential distribution equations and an electrolyte concentration distribution equation supplemented by the dependence of the electrode surface current on the overvoltage and equations that determine the electrode pore structure depending on the masses transferred inside the electrode. The electric potential and diffuse component mass transfer equations are written within the framework of the modern theory of effective electrical conductivity in batteries with account for current exchange between the solid electrodes and the liquid electrolyte. The research results showed the following. A change in the resistance of the separator (a change in porosity) has little effect, if any, on the electrode current densities, but it causes some change in the potentials themselves. A change in the resistance of the electrolyte affects both the electrode potentials and the internal current distribution between the electrodes and the electrolyte.

A real-time analysis of protein transport via the twin arginine translocation pathway in response to different components of the protonmotive force

The twin arginine translocation (Tat) pathway transports folded protein across the cytoplasmic membrane in bacteria, archaea, and across the thylakoid membrane in plants as well as the inner membrane in some mitochondria. In plant chloroplasts, the Tat pathway utilizes the protonmotive force (PMF) to drive protein translocation. However, in bacteria, it has been shown that Tat transport depends only on the transmembrane electrical potential (Δψ) component of PMF invitro. To investigate the comprehensive PMF requirement in Escherichia coli, we have developed the first real-time assay to monitor Tat transport utilizing the NanoLuc Binary Technology in E.coli spheroplasts. This luminescence assay allows for continuous monitoring of Tat transport with high-resolution, making it possible to observe subtle changes in transport in response to different treatments. By applying the NanoLuc assay, we report that, under acidic conditions (pH= 6.3), ΔpH, in addition to Δψ, contributes energetically to Tat transport invivo in E.coli spheroplasts. These results provide novel insight into the mechanism of energy utilization by the Tat pathway.

Late potentials assessment - an useful tool for Brugada Syndrome risk stratification

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Brugada syndrome (BrS) is a channelopathy confining an increased risk of sudden cardiac death (SCD). Asymptomatic patients (pts) management remains challenging enhancing the necessity for additionally stratification tools. Purpose To evaluate the role of the non-invasive assessment of late potentials (LP) based on SA-ECG as stratification tools in a BrS cohort. Methods Prospective, observational single-center study of pts with BrS with the following criteria (1) Type 1 Brugada ECG pattern, either spontaneous or drug induced; (2) SA-ECG performed before anti-arrhythmic treatment; (3) minimum follow up duration of 12 months. LPs were evaluated by SA-ECG with determination of the total filtered QRS duration (fQRS); root mean square voltage of the 40ms terminal portion of the QRS (RMS40) and duration of the low amplitude electric potential component of the terminal portion of the QRS (LAS40) in conventional and modified right precordial leads. Malignant arrhythmic events (MAEs) were defined as a composite event of SCD or appropriate ICD shocks. Association of relevant risk factors and MAE was conducted with Univariate Cox regression analysis, as well as SA-ECG evaluated as a continuous and categorical divided on standard cut-offs (fQRS &amp;gt;114ms, RMS40&amp;lt;20µV, LAS40&amp;gt;38ms). A risk score for predicting MAE was computed incorporating the significant LPs variables. Results A total of 106 pts fulfilled the inclusion criteria (mean age: 48 ± 12 years, 67.9% male), 52 (49.1%) with type 1 spontaneous pattern. The majority were asymptomatic at baseline (81.1%) while 13 presented with syncope and 3 with polymorphic VT/cardiac arrest. A total of 10 (7.1%) pts MAEs were documented during a mean 4.7 years - 4 with SCD and 6 with appropriate ICD shocks. Clinical presentation with a polymorphic VT/cardiac arrest (p &amp;lt;0.001) and LP evaluated on SA-ECG were significant predictors of MAE on univariate analysis, except for RMS40 on conventional leads. Neither of the common risk factors (male gender, spontaneous type 1 pattern at baseline, previous syncope or the presence of a pathogenic SCN5A mutation) were predictors of MAE during follow-up– figure 1. Positive LPs defined by standard cut-offs, in all variables and leads, were significantly associated with an increased risk of MAE during follow-up – figure 2. A LP score was computed incorporating the standard cut-offs on conventional leads. The presence of 2 and 3 positive LP represented an additionally 4.7-fold increased risk of MAE during follow-up (HR 4.693, 95% CI 1.506-14.624, p = 0.008) – figure 2. Conclusion LPs based on noninvasive assessment SAECG represent an useful prognostic stratification tool in BrS. A LP score based on standard cut-offs identified a subset of pts at a higher risk of events and who may deserve individualized preventive strategies.

Armeniaspirol analogues disrupt the electrical potential (ΔΨ) of the proton motive force

The armeniaspirol family of natural product antibiotics have been shown to inhibit the ATP-dependent proteases ClpXP and ClpYQ and disrupt membrane potential through shuttling of protons across the membrane. Herein we investigate their ability to disrupt the proton motive force (PMF). We show, using a voltage sensitive, that armeniaspiols disrupt the electrical membrane potential (ΔΨ) component of the PMF and not the transmembrane proton gradient (ΔpH). Using checkerboard assays, we confirm this by showing antagonism, with kanamycin, an antibiotic that required ΔΨ for penetration. By evaluating the antibiotic activity and disruption of the PMF by sixteen armeniaspirol analogs, we find that disruption of the PMF is necessary but not sufficient for antibiotic activity. Analogs that are potent disruptors of the PMF without possessing the ability to inhibit ClpXP and ClpYQ are not potent antibiotics. Thus we propose that the armeniaspirols utilize a dual mechanism of action where they disrupt PMF and inhibit the ATP-dependent proteases ClpXP and ClpYQ. This type of dual mechanism has been observed in other natural product-based antibiotics, most notably chelocardin.

Active Electric Dipole Energy Sources: Transduction via Electric Scalar and Vector Potentials.

The creation of electromagnetic energy may be realised by engineering a device with a method of transduction, which allows an external energy source, such as mechanical, chemical, nuclear, etc., to be impressed into the electromagnetic system through a mechanism that enables the separation of opposite polarity charges. For example, a voltage generator, such as a triboelectric nanogenerator, enables the separation of charges through the transduction of mechanical energy, creating an active physical dipole in the static case, or an active Hertzian dipole in the time-dependent case. The net result is the creation of a static or time-dependent permanent polarisation, respectively, without an applied electric field and with a non-zero vector curl. This system is the dual of a magnetic solenoid or permanent magnet excited by a circulating electrical current or fictitious bound current, respectively, which supplies a magnetomotive force described by a magnetic vector potential and a magnetic geometric phase proportional to the enclosed magnetic flux. Thus, the active electric dipole voltage generator has been described macroscopically by a circulating fictitious magnetic current boundary source and exhibits an electric vector potential with an electric geometric phase proportional to the enclosed electric flux density. This macroscopic description of an active dipole is a semi-classical average description of some underlying microscopic physics, which exhibits emergent nonconservative behaviour not found in classical closed-system laws of electrodynamics. We show that the electromotive force produced by an active dipole in general has both electric scalar and vector potential components to account for the magnitude of the electromotive force it produces. Independent of the electromagnetic gauge, we show that Faraday’s and Ampere’s law may be derived from the time rate of change of the magnetic and dual electric geometric phases. Finally, we analyse an active cylindrical dipole in terms of scalar and vector potential and confirm that the electromotive force produced, and hence potential difference across the terminals is a combination of vector and scalar potential difference depending on the aspect ratio (AR) of the dipole. For long thin active dipoles (AR approaches 0), the electric field is suppressed inside, and the voltage is determined mainly by the electric vector potential. For large flat active dipoles (AR approaches infinity), the electric flux density is suppressed inside, and the voltage is mainly determined by the scalar potential.

SAECG - advances in Brugada stratification

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Brugada syndrome (BrS) is a relevant cause of sudden cardiac death (SCD) in young adults. Several risk factors have been identified, but clinical decision making remains extremely challenging, particularly in asymptomatic patients. Purpose To explore the usefulness of the non-invasive assessment of late potentials (LPs) based signal-averaged ECG (SAECG) for risk stratification in BrS. Methods Prospective single-center study of patients with BrS included from 2003 to 2021. LPs were evaluated by SA-ECG with determination of the total filtered QRS duration (fQRS), root mean square voltage of the 40ms terminal portion of the QRS (RMS40) and duration of the low amplitude electric potential component of the terminal portion of the QRS (LAS40) in conventional and modified right precordial leads. The primary endpoint was the occurrence of malignant arrhythmic events (MAEs), defined as a composite of SCD or appropriate shocks. Uni- and multivariate Cox regression survival analyses were used to identify significant prognostic predictors considering the clinical, genetic, and electrocardiographic characteristics as well as the tercile distribution of the SAECG parameters. A risk score was computed incorporating the significant LPs variables and its usefulness for prognostic stratification was explored using Kaplan Meier survival analysis. Results Our cohort consisted of 117 patients (mean age: 47±13 years, 33% male), including 75 (65%) with type 1 spontaneous pattern and 92 (79%) asymptomatic individuals. Symptoms at presentation included syncope in 16 pts (14%) and polymorphic VT/cardiac arrest in 4 (3.4%). During a median follow-up of 4.1±0.3 years, 8 pts (6.8%) suffered MAEs: 3 (2.6%) with SCD and 5 (4.3%) with appropriate shocks. The risk of events differed in relation to the several SAECG parameters (Table 1), increasing linearly with the fQRS duration determined either in the conventional (HR 1.03, 95% CI 1.01-1.06, p=0.008) or modified leads (HR: 1.03, 95% CI 1.01- 1.05, p=0.003). The SAECG score incorporated as risk markers a fQRS ≥113ms and a RMS40 &amp;lt;13 μV. Patients with both risk markers presented a 7-fold increased risk (HR 7.17, 95% CI 1.29-40, p = 0.025), independently of the baseline symptomatic status and ECG pattern. Conclusion This study shows that the non-invasive assessment of LPs based on SAECG is useful for prognostic stratification of BrS. It was possible to identify a subset of patients presenting a high risk of events who may deserve individualized preventive strategies.

Risk stratification in patients with Brugada syndrome: the role of the late potentials evaluated by signal-averaged ECG

Abstract Introduction Brugada syndrome (BS) is a relevant cause of sudden death in individuals without structural heart disease. The accuracy of the available methods for risk stratification is very limited and the investigation of new methodologies to improve the identification of patients at risk is under intensive investigation. Recently the pathophysiological relevance of anomalous, fragmented and prolonged electrograms on the epicardial surface of the right ventricular outflow tract (RVOT) has been described. Therefore, the study of signal-averaged ECG (SA-ECG) has become attractive since it may allow the non-invasive evaluation of these electrical anomalies. In order to maximize the detection capacity and to focus the evaluation in the RVOT, we developed an alternative methodology of electrode positioning directed to this area of interest. Purpose To characterize the study of late potentials (LP) by SA-ECG in patients with SB and to evaluate its association with the occurrence of arrhythmia events. Methods Prospective single centre study of patients (pts) with BS. LP were evaluated by SA-ECG with determination of the total filtered QRS duration (fQRS), root mean square voltage of the 40 ms terminal portion of the QRS (RMS40) and duration of the low amplitude electric potential component (40 microV) of the terminal portion of the QRS (LAS40) in conventional and modified leads (addressed to RVOT). The association of LP with the risk of definite malignant dysrhythmias due to sudden death, ventricular fibrillation, ventricular tachycardia or appropriate shock of the implantable cardioverter defibrillator (ICD) was evaluated and the acuity of the prognostic stratification was determined by the area under the receiver operator characteristic curve (ROC). Results A total of 76 pts (69.7% men, age 48±12 years) were studied, of which 33 had a spontaneous type 1 pattern and 43 had a type 1 pattern induced by flecainide. During a median follow-up of 1.6 years, 13 pts (17.1%) had symptoms potentially related to BS and 6 (10.5%) had malignant arrhythmias [including two pts who suffered sudden death (2.6%). The pts who had malignant dysrhythmias presented higher values of fQRS (125±23 vs. 108±18, p=0.046) and LAS40 (54±13 vs. 40±11, p=0.014), and lower values of RMS40 only in the modified leads (11±5 vs. 22±19, p=0.041). The parameters of the SA-ECG were significant prognostic predictors. The acuity of each of the parameteres alone was moderate and the parameters that were identified as more powerful predictors of risk were those derived from the modified leads (Figure). Conclusion The LP evaluated by SA-ECG may be relevant in the prognostic stratification of patients with BS, since it seems to be associated with the risk of malignant ventricular arrhythmias. Funding Acknowledgement Type of funding sources: None.

Proton motive force in plant photosynthesis dominated by ΔpH in both low and high light.

The proton motive force (pmf) across the thylakoid membrane couples photosynthetic electron transport and ATP synthesis. In recent years, the electrochromic carotenoid and chlorophyll absorption band shift (ECS), peaking ∼515 nm, has become a widely used probe to measure pmf in leaves. However, the use of this technique to calculate the parsing of the pmf between the proton gradient (ΔpH) and electric potential (Δψ) components remains controversial. Interpretation of the ECS signal is complicated by overlapping absorption changes associated with violaxanthin de-epoxidation to zeaxanthin (ΔA505) and energy-dependent nonphotochemical quenching (qE; ΔA535). In this study, we used Arabidopsis (Arabidopsis thaliana) plants with altered xanthophyll cycle activity and photosystem II subunit S (PsbS) content to disentangle these overlapping contributions. In plants where overlap among ΔA505, ΔA535, and ECS is diminished, such as npq4 (lacking ΔA535) and npq1npq4 (also lacking ΔA505), the parsing method implies the Δψ contribution is virtually absent and pmf is solely composed of ΔpH. Conversely, in plants where ΔA535 and ECS overlap is enhanced, such as L17 (a PsbS overexpressor) and npq1 (where ΔA535 is blue-shifted to 525 nm) the parsing method implies a dominant contribution of Δψ to the total pmf. These results demonstrate the vast majority of the pmf attributed by the ECS parsing method to Δψ is caused by ΔA505 and ΔA535 overlap, confirming pmf is dominated by ΔpH following the first 60 s of continuous illumination under both low and high light conditions. Further implications of these findings for the regulation of photosynthesis are discussed.

Boundary Element Modeling for Simulation and Optimization of Three-Temperature Anisotropic Micropolar Magneto-thermoviscoelastic Problems in Porous Smart Structures Using NURBS and Genetic Algorithm

The main objective of the present paper is to propose a new boundary element modeling technique for simulation and optimization of three-temperature micropolar magneto-thermoviscoelastic problems in anisotropic porous smart structures, where we implemented the genetic algorithm (GA), as a method of optimization based on the free form deformation (FFD) methodology to improve the performance of our proposed technique. Two numerical examples are presented herein, in order to prove that the proposed technique is able to optimize the shape of the domains with minimum computational effort. A nonuniform rational B-spline curve (NURBS) has been introduced to define the optimum boundary where it decreases the number of control points and offers a new degree of versatility in the design of various different shapes. The profiles of the items considered shall be represented by the FFD methodology. The location vectors of the FFD control points are known to be the genes, and then the chromosomes for the profiles are determined by the gene sequence. The population is made up of several chromosomes individuals, where the fitness functions of individuals are assessed using BEM. The numerical results are depicted graphical forms to show the effects of viscosity and magnetic fields on the three temperatures, displacement components, microrotation components, pore pressure, electric potential, and thermal stress components. The validity, accuracy, and computational efficiency of the proposed BEM technique were demonstrated by comparing our BEM-obtained results with the corresponding results of normal mode analysis method (NMAM), finite difference method (FDM), and finite element method (FEM).

Flow Electrification of a Corona-Charged Polyethylene Terephthalate Film.

Corona charging of a free-standing polymer film can produce a quasi-permanent potential difference across the film thickness, while the absolute amplitude of the surface voltage may be highly sensitive to the free charges. To precisely control the voltage distribution, we investigated the flow electrification technology by exposing corona-charged polyethylene terephthalate films to sodium salt solutions. The surface voltage and the free-charge density were adjusted by the salt concentration, the anion size, and the flow rate. The dipolar component of electric potential remained unchanged. This result has significant scientific interest and technological importance to surface treatment, filtration, energy harvesting, among others.

Two-dimensional problem of thermoelectric materials with an elliptic hole or a rigid inclusion

The two-dimensional problems of an elliptic hole or a rigid inclusion embedded in a thermoelectric material subjected to uniform electric current density and energy flux at infinity are studied based on the complex variable method of Muskhelishvili and conformal mapping technique. The closed-form solutions of electric potential, temperature and stress components are presented according to electrical insulated and thermal exact boundary conditions on the rim of the hole or inclusion. Numerical results are carried out to illustrate the influence of the value of major to minor axis ratio of the elliptic geometry and heat conductivity of inhomogeneity on thermoelectric and stress fields. It is found that energy flux at surfaces of the hole or rigid inclusion does not vanish due to the Joule heat and Seebeck effect when the electric field is applied. In addition, stress induced by applied electric field has a non-linear relationship with the electric current density. The heat conductivity of the air inside the elliptic hole reduces the concentration factors of energy flux and stress. However, the concentration factors of energy flux and stress at the bonding interface increase with the increasing values of heat conductivity of the flat rigid inclusion.

Coupled Rayleigh waves in a 2-mm piezoelectric layer over a porous piezo-thermoelastic half-space

Propagation of coupled Rayleigh-type waves in a 2-mm piezoelectric layer over a porous piezo-thermoelastic half-space is investigated in this paper. The governing equations for an orthorhombic porous piezo-thermoelastic half-space and 2-mm piezoelectric layer are discussed. The dispersion relations have been numerically derived. The phase velocities of Rayleigh waves are obtained for different types of electric–thermal boundary conditions at the interface and at the free surface. The variations of mechanical displacements, electric potential and temperature component with the non-dimensional wave number are obtained. The effects of different electric–thermal boundary conditions on the phase velocity have also been discussed. The dispersion curves and attenuation coefficients of wave propagation are presented graphically. Some reduced cases are also discussed.

An &lt;italic&gt;In Situ&lt;/italic&gt; Measurement Method for Electric Potential at Head-Disk Interface Using a Thermal Asperity Sensor

The electrostatic force at head–disk interface (HDI) becomes increasingly significant when the head–disk clearance is dropping into 1 nm scheme. Therefore, detecting and eliminating the electric potential in the HDI is a critical task for hard disk drives. To that end, this paper proposed an in situ measurement method for electric potential at HDI using a thermal asperity (TA) sensor. When calibrating the electric potential, both dc and ac components of the external voltage were supplied to the disk. As a result, the output of the TA sensor to the first harmonic of the ac component was linearly increasing with the decrease in the dc components. Experimental results show that this method is more efficient and flexible than the traditional methods.

Coupled electro-elastic analysis of functionally graded piezoelectric material plates

A unified formulation of finite layer methods (FLMs), based on the Reissner mixed variational theorem (RMVT), is developed for the three-dimensional (3D) coupled electro-elastic analysis of simply-supported, functionally graded piezoelectric material (FGPM) plates with open- and closed-circuit surface conditions and under electro-mechanical loads. In this formulation, the material properties of the plate are assumed to obey an exponent-law varying exponentially through the thickness coordinate, and the plate is divided into a number of finite rectangular layers, in which the trigonometric functions and Lagrange polynomials are used to interpolate the in- and out-of-plane variations of the primary field variables of each individual layer, respectively, such as the elastic displacement, transverse shear and normal stress, electric potential, and normal electric displacement components. The relevant orders used for expanding these variables in the thickness coordinate can be freely chosen as the linear, quadratic and cubic orders. Four different mechanical/electrical loading conditions applied on the top and bottom surfaces of the plate are considered, and the corresponding coupled electro-elastic analysis of the loaded FGPM plates is undertaken. The accuracy and convergence rate of the RMVT-based FLMs are assessed by comparing their solutions with the exact 3D piezoelectricity ones available in the literature.

Three-dimensional dynamic responses of carbon nanotube–reinforced composite plates with surface-bonded piezoelectric layers using Reissner’s mixed variational theorem–based finite layer methods

A unified formulation of finite layer methods based on the Reissner’s mixed variational theorem is developed for the three-dimensional dynamic responses of simply supported, functionally graded carbon nanotube–reinforced composite plates with surface-bonded piezoelectric sensor and actuator layers and closed- and open-circuit surface conditions. In the formulation, the plate is divided into a number of finite rectangular layers, in which the trigonometric functions and Lagrange polynomials are used to interpolate the in- and out-of-plane variations in the primary field variables of each individual layer, respectively, such as the elastic displacement, transverse shear and normal stress, electric potential, and normal electric displacement (flux) components. The relevant orders used for expansion of these variables in the thickness coordinate can be freely chosen, such as linear, quadratic, or cubic ones. Four different through-thickness distributions of carbon nanotubes in the carbon nanotube–reinforced composite layer are considered, and the effective material properties of the layer are estimated using the rule of mixtures. The accuracy and convergence rate of the frequency parameters of the sandwiched hybrid carbon nanotube–reinforced composite and piezoelectric plates obtained using assorted Reissner’s mixed variational theorem–based finite layer methods are assessed by comparing their solutions with the exact three-dimensional solutions available in the literature.

An analytical solution for dynamic behavior of thick doubly curved functionally graded smart panels

In this paper, an analytical solution is presented for free vibration and dynamic behavior of doubly curved laminated shell consisting of a functionally graded core layer and surface attached functionally graded piezoelectric layers. Shell through-thickness kinematics is based on higher order shear deformation theory of shells, whereas a quadratic variation is assumed for electric potential. Using Hamilton’s principle and Maxwell’s equation, the governing equations of motion under mechanical loads are derived as seven highly coupled partial differential equations. Implementing Laplace transformation, doing few mathematical operations and using Laplace inverse method, time dependencies of displacement components are expressed in explicit phrases. Besides numerical results for shell natural frequencies, effects of different material properties and shell geometries on the transient response are discussed in details. In particular the influence of shell curvature on the spectra of maximax response has been studied. It is found that, these parameters play major roles on determining the time-histories of the electric potential and displacement components.

Scattering of antiplane shear waves by two collinear coplanar rigid strips in a piezoelectric material

In this paper the dynamic interaction between two collinear rigid strips in a piezoelectric material under antiplane shear waves is investigated when the strips are metallic and grounded. By using the Fourier transforms , the solution of the problem is reduced to the solution of a pair of triple integral equations. The pair of triple integral equations are solved analytically. Analytic expressions for shear stress, mechanical shear intensity factors, electric displacement intensity factors, displacement component and electrical potential function are obtained for small wave numbers and the results for mechanical shear intensity factors. electric displacement intensity factors. electric potential and displacement component are shown graphically.

Wave characteristics in functionally graded piezoelectric hollow cylinders

Based on linear three-dimensional piezoelasticity, the Legendre orthogonal polynomial series expansion approach is used for determining the wave characteristics in hollow cylinders composed of the functionally graded piezoelectric materials (FGPM) with open circuit. The displacement and electric potential components, expanded in a series of Legendre polynomials, are introduced into the governing equations along with position-dependent material constants so that the solution of the wave equation is reduced to an eigenvalue problem. Dispersion curves for FGPM and the corresponding non-piezoelectric hollow cylinders are calculated to show the piezoelectric effect. The influence of the ratio of radius to thickness is discussed. Electric potential and displacement distributions are used to show the piezoelectric effect on the flexural torsional mode. The influence of the polarizing direction on the piezoelectric effect is illustrated. For the radial and axial polarization, the piezoelectric effect reacts mostly on the longitudinal mode. For circumferential polarization, the piezoelectric effect reacts mostly on the torsional mode. In the FGPM hollow cylinder, piezoelectricity can weaken the guided wave dispersion.