Piezoelectric Coupling Effects Research Articles

Analysis of a friction-induced vibration piezoelectric energy generator under linear, bi-linear, and impact conditions

The mismatch in natural frequencies between the piezoelectric energy generator and the energy source affects its energy generation performance. In this research, a novel piezoelectric energy generator with linear, bi-linear, and impact design configurations is proposed. The energy generator utilizes friction as excitation to achieve self-exciting friction-induced vibration (FIV) close to the systems’ resonant frequencies for piezoelectric energy generation. The dynamic response under FIV is described by a mathematical model incorporating the piezoelectric coupling effect. The energy generation from piezoelectric material is evaluated by simulating the charging process of a capacitor using an iterative method. The reliability of the model and the stable high-frequency FIV phenomenon with linear, bi-linear, and impact design configurations are validated by experiment. Furthermore, parameter studies are conducted to investigate their effect on the efficiency and effectiveness of energy generation. With a normal load FN = 30 N and an initial sliding velocity v0 = 0.542 m/s, the linear, bi-linear, and impact design configurations yield peak-to-peak voltages of approximately 2.9 V, 3.8 V, and 20.6 V, respectively. Higher voltages can be generated under optimal operating conditions. The proposed energy generator can be integrated into rotating or sliding equipment to harness the energy derived from FIV. Enhanced energy generation performance can be achieved by modifying structural design and incorporating materials with better properties. The current study paves the way for piezoelectric energy generation using FIV and explores the potential of utilizing dynamic frictional signals in sensing and structural health monitoring scenarios.

Phase field model for brittle fracture in multiferroic materials

Multiferroic materials, which simultaneously possess piezomagnetic, piezoelectric, and electromagnetic coupling effects, have a wide range of applications in various fields. Multiferroic materials are generally brittle with low fracture toughness, and accurate prediction of the fracture behaviors of multiferroics is challenging. In this work, a phase field model for brittle fracture in multiferroic materials is developed with the help of the Hamilton principle. In light of the second law of thermodynamics, the constitutive equations are derived in the context of the phase field method. The present theoretical framework unifies two classical phase field models and four combinations of the electric and magnetic boundary conditions. The residual controlled staggered algorithm, which enjoys a higher accuracy and lower computational cost, is extended to the fracture problems in the context of magneto-electro-elasticity. Systematic numerical simulations are performed in both 2D and 3D cases. The influences of the external magnetic field, electric field, and electric and magnetic boundary conditions on fracture behaviors of multiferroic materials are studied in detail. The applied magnetic field may not only accelerate or delay the fracture, but also influence the crack path. The present work is beneficial to assess the safety of multiferroic-based devices in engineering applications.

Importance of Three-Dimensional Piezoelectric Coupling Modeling in Quantitative Analysis of Piezoelectric Actuators

This paper demonstrates the importance of three-dimensional (3-D) piezoelectric coupling in the electromechanical behavior of piezoelectric devices using three-dimensional finite element analyses based on weak and strong coupling models for a thin cantilevered piezoelectric bimorph actuator. It is found that there is a significant difference between the strong and weak coupling solutions given by coupling direct and inverse piezoelectric effects (i.e., piezoelectric coupling effect). In addition, there is significant longitudinal bending caused by the constraint of the inverse piezoelectric effect in the width direction at the fixed end (i.e., 3-D effect). Hence, modeling of these effects or 3-D piezoelectric coupling modeling is an electromechanical basis for the piezoelectric devices, which contributes to the accurate prediction of their behavior.

Enhanced SERS and catalytic performance via piezoelectric and plasmonic coupling effects for organic pollutant molecule degradation

The accurate detection and efficient catalytic treatment of pollutants are essential for environmental protection. In this study, we propose a Au/Ag/CuO nanowire (NW)/polyvinylidene fluoride (PVDF) substrate capable of achieving the highly sensitive surface-enhanced Raman scattering (SERS) detection as well as effective piezoelectric photodegradation of organic pollutant molecules. The piezoelectric modulation of the SERS performance of the Au/Ag/CuO NW/PVDF substrate was demonstrated experimentally using rhodamine 6 G and Crystal Violet. The piezoelectric photocatalytic performance was investigated using malachite green and methylene blue. The enhanced SERS and catalytic performance can be attributed to the coupling of the piezoelectric and plasmonic effects of the CuO NW/PVDF and Au/Ag bimetals. The proposed Au/Ag/CuO NW/PVDF substrate provides a robust method that employs plasmonic and piezoelectric materials for high-performance SERS detection and piezoelectric photocatalysis. • We combined sensitive SERS and effective photodegradation for pollutant molecule. • The Raman intensity can be increased by a factor of 1.5 through piezoelectric modulation. • The catalytic efficiency reaches 94.5% and 98.8% respectively through piezoelectric modulation. • The proposed substrate can in-situ degrade dyes in water.

Size-dependent and piezoelectric effects on SH wave propagation in functionally graded plates

This paper is concerned with the propagation of shear horizontal waves in a functionally graded piezoelectric small-scaled plate. In the context of the modified couple stress theory, the Legendre orthogonal polynomial method is utilized to derive the solutions based on the explicit functionally graded model. Four different electric boundary conditions are considered. The obtained results are compared with those by the global matrix method and the advantages of the polynomial method are indicated. Furthermore, the couple stress effect and piezoelectric effect on the SH waves are investigated. Numerical results indicate that the couple stress and piezoelectric coupling effects on SH propagation are mutually inhibited.

Research on material selection of force-sensitive element for high-frequency dynamic piezoelectric pressure sensor

The high-frequency dynamic piezoelectric pressure sensor has the advantages of simple structure, long service life, high natural frequency, excellent signal-to-noise ratio and great sensitivity. It is appropriate for measuring high dynamic, dynamic or quasi-static pressure changes and pressure fluctuations. And this kind of sensor is widely utilized in the shock wave testing. The force-sensitive element is one of the main factors affecting the static and dynamic performance of piezoelectric pressure sensors. Basing on the piezoelectric equation and coupling effect between mechanics and electricity, in this paper, the finite element model of the high-frequency dynamic piezoelectric pressure sensor is established. The influences of the force-sensing element on the sensitivity of the sensor are analysed. Referential suggestions for choosing force-sensitive element of high-frequency dynamic piezoelectric pressure sensor are provided.

Dynamics of a delayed Duffing-type energy harvester under narrow-band random excitation

In this paper, a Duffing-type energy harvester with time delay circuit under narrow-band random excitation is studied by using the method of multiple scales. The analytical expressions of the steady-state responses near the principal resonance and their stable conditions are derived. Results show that the phenomenon of stochastic jump is found, and the operational bandwidth of the nonlinear energy harvester can be extended. The effects of frequency detuning, noise intensity, time delay, piezoelectric coupling, and time constant ratio on the dynamical behaviors are discussed. From the viewpoint of improving system performance and optimizing harvester design, a proper choose of time delay and feedback gain is proposed by the power conversion efficiency and the RMS voltage. It indicates that the negative feedback gain is favorable for an energy harvester to provide more electrical output power and miniaturize design. Moreover, the Monte Carlo simulations are given to verify the validity of the theoretical method.

High-power characteristics of a piezoelectric bar vibrating in extensional mode with the effect of longitudinal piezoelectric coupling

High-power characteristics of a piezoelectric bar vibrating in extensional mode with the effect of longitudinal piezoelectric coupling

A Self-Powered Biosensor for Monitoring Maximal Lactate Steady State in Sport Training

A self-powered biosensor for monitoring the maximal lactate steady state (MLSS) during exercise has been developed for intelligently assisting training system. It has been presented to create poly (vinylidene fluoride) (PVDF)/Tetrapod-shaped ZnO (T-ZnO)/enzyme-modified nanocomposite film through an efficient and cost-effective fabrication process. This sensor can be readily attached to the skin surface of the tester. Due to the piezoelectric surface coupling effect, this biosensor can monitor/sense and analyze physical information in real-time under the non-invasive condition and work independently without any battery. By actively outputting piezoelectric signals, it can quickly and sensitively detect body movements (changes of joint angle, frequency relative humidity during exercise) and physiological information (changes of lactate concentration in sweat). A practical application has been demonstrated by an excellent professional speed skater (male). The purpose of this study is to increase the efficiency of MLSS evaluation, promote the development of piezoelectric surface coupling effect and motion monitoring application, develop an intelligently assisting training system, which has opened up a new direction for human motion monitoring.

Stable transitions between remote equilibria of post-buckled beams using piezoelectric actuation

This paper considers the extent to which a clamped-clamped post-buckled beam bonded to two elongating piezoelectric actuators can be made to stably transition between remote equilibria. The electromechanical system is modeled using elastica theory with extensions to account for the influence of the actuators on the structure. It expresses this piezoelectric coupling effect in terms of a non-dimensional parameter, σ, that can be easily calculated for candidate substrate/actuator configurations. Parameter studies determining the threshold values of σ required to execute stable transitions under different actuation and loading situations are presented. The results indicate that the lowest threshold values of σ occur when the beam is actuated from approximately 15%–85% of its span. Experiments validate the numerical results and offer the first physical demonstrations of the use of piezoelectric actuators to achieve stable transitions between remote equilibria.

Tunable phononic structures using Lamb waves in a piezoceramic plate

Phononic crystals made of piezoceramic materials allow for frequency band structure tunability due to the ease of electric command use. In this paper, we develop a full elastodynamic model, taking into account piezoelectric coupling effects for the band-structure calculation of Lamb eigenmodes of a phononic crystal consisting of a piezoceramic plate with a one-dimensional periodic array of electrodes set on both sides. The dispersion-relation characteristics of these eigenmodes are nondestructively tuned via external circuit impedance loads coupled to the phononic plate, e.g., through inductance loads inducing tunable resonant flat bands that hybridize with the Lamb modes of the elastic plate, thus opening up hybridization gaps. It is shown that additional control of the shape of these resonant bands can be achieved by incorporating an impedance interconnecting two adjacent electrodes of the same side, the whole structure forming an electric quadripole. This behavior can be easily predicted with the help of our formalism combined with a simplified electric line model of the phononic crystal plate.

On dispersion relations in smart laminated fiber-reinforced composite membranes considering different piezoelectric coupling effects

Wave propagation characteristics are determined for smart laminated fiber-reinforced composite cylindrical membrane shells with different piezoelectric coupling effects. Wave motion equations are derived using the membrane shell model. By solving an eigenvalue problem, dispersion curves of the wave motion are obtained for different axial and circumferential wave numbers. The effects of piezoelectric coupling, fiber orientation, stacking sequence, and material properties of the host shell on wave behaviors are investigated. The results of this paper can be used for studies on dynamic stability of piezoelectric coupled laminated fiber-reinforced composite shell structures and in design of smart structures with the piezoelectric materials for the applications of damage detection and structural health monitoring.

Analytical model of mechanically excited piezoelectric unimorph beams.

A model is presented of a composite beam with one elastic and one piezoelectric layer. A reduced set of piezoelectric equations of state that has only the longitudinal components of stress and strain and the transverse components of electric field and charge density is consistently used to include the effect of piezoelectric coupling in all the equations. The equi-potential boundary conditions on the electrodes, the open-circuit condition, and the Gauss condition are satisfied. The position of the neutral axis and the dynamic equilibrium equation are derived after including the effect of piezoelectric coupling. All equations are combined to derive an equation of motion that contains only the displacement and the mechanical excitation. The solution to the equation is expressed in terms of a complete set of functions and an auxiliary function that contains the electric potential. The latter is needed to satisfy piezoelectric boundary conditions at the ends of the beam. The electric potential varies along the length of the beam and has a quadratic variation between the electrodes. Analytical expressions for displacement and potential, and numerical results at low frequencies and in the neighborhood of resonance, are presented for certain sets of boundary conditions.

A multiscale model for damage progression and detection in piezo/pyroelectric composite laminates

Assessment of damage initiation and progression in composite structures reinforced with electrically active filaments is modeled in a multiscale analysis. The analysis developed is a two-tier, interactive analysis, which involves two length scales; macroscopic, and microscopic. The proposed multiscale analysis provides seamless integration of the mechanics at the two length scales, including piezoelectric and pyroelectric coupling effects and damage under overall thermomechanical loads and an electric field applied to electroactive fibers. The macromechanical analysis is performed for multidirectional, fibrous laminates using the lamination theory, including bending, and the micromechanical analysis is performed using a two-phase model and a periodic array model. The effect of eigenstrains caused by thermomechanical, electromechanical, and thermoelectric coupling at both the microscopic and macroscopic length scales is accounted for by a two-tier transformation field analysis (TFA).

Parametric Analysis and Experimental Verification of a Hybrid Vibration Energy Harvester Combining Piezoelectric and Electromagnetic Mechanisms

Considering coil inductance and the spatial distribution of the magnetic field, this paper developed an approximate distributed-parameter model of a hybrid energy harvester (HEH). The analytical solutions were compared with numerical solutions. The effects of load resistances, electromechanical coupling factors, mechanical damping ratio, coil parameters and size scale on performance were investigated. A meso-scale HEH prototype was fabricated, tested and compared with a stand-alone piezoelectric energy harvester (PEH) and a stand-alone electromagnetic energy harvester (EMEH). The peak output power is 2.93% and 142.18% higher than that of the stand-alone PEH and EMEH, respectively. Moreover, its bandwidth is 108%- and 122.7%-times that of the stand-alone PEH and EMEH, respectively. The experimental results agreed well with the theoretical values. It is indicated that the linearized electromagnetic coupling coefficient is more suitable for low-level excitation acceleration. Hybrid energy harvesting contributes to widening the frequency bandwidth and improving energy conversion efficiency. However, only when the piezoelectric coupling effect is weak or medium can the HEH generate more power than the single-mechanism energy harvester. Hybrid energy harvesting can improve output power even at the microelectromechanical systems (MEMS) scale. This study presents a more effective model for the performance evaluation and structure optimization of the HEH.

Mathematical justification of the obstacle problem in the case of piezoelectric plate

This paper aims at properly justifying the modeling of a thin piezoelectric plate in unilateral contact with a rigid plane. In order to do that we start from the three-dimensional non-linear Signorini problem which couples the elastic and the electric effects. By an asymptotic analysis we study the convergence of the displacement field and of the electric potential as the thickness of the plate goes to zero. We establish that, at the limit, the in-plane elastic components and the electric potential are coupled and solve a bilateral linear piezoelectric problem. However the transverse mechanical displacement field, is independent of the electric effect and solves a two-dimensional elastic obstacle problem. We also investigate the very popular case of cubic crystals and show that, for thin plates, the piezoelectric coupling effect disappears.

Three-dimensional perturbation solution of the natural vibrations of piezoelectric rectangular plates

The paper discusses a perturbation solution of the natural frequencies and mode shapes of a piezoelectric rectangular plate modelled as a three-dimensional body. The coupled theory of piezoelectricity is used, with the governing equations consisting of one electrostatic and three mechanical equations coupled through the piezoelectric effect. Analytical perturbation formulas up to the first-order terms have been derived and used. An important difference of the present analysis as compared to the classical perturbation method consists in that the small parameter enters not only the governing equations but the boundary conditions as well. To address this complication an efficient new approach that makes use of generalized functions has been proposed. Results of the natural frequencies and mode shapes obtained by the perturbation method are discussed for a thin piezoelectric rectangular plate, a thick plate and a piezoelectric parallelepiped. All the results obtained using the perturbation method have been compared with the exact solutions of the coupled electromechanical problem. The proposed perturbation approach furnishes an efficient approximate method of studying the coupled piezoelectric vibration problem. The main advantage of the method derives from the fact that only the elastic solution is required, the effect of piezoelectric coupling being accounted for at a post-processing stage.

Optimization of electrooptic and pieozoelectric coupling effects in tetragonal relaxor-PT ferroelectric single crystals

The electrooptic and piezoelectric coupling effects in tetragonal relaxor-based ferroelectric 0.62Pb(Mg1/3Nb2/3)O3–0.38PbTiO3 (PMN–0.38PT) and 0.88Pb(Zn1/3Nb2/3)O3–0.12PbTiO3 (PZN–0.12PT) single-domain crystals have been analyzed by the coordinate transformation. The orientation dependence of the electrooptic and half-wave voltage was calculated based on the full sets of refractive indices, electrooptic and piezoelectric coefficients. The optimum orientation cuts for achieving the best electrooptic coefficient and half-wave voltage were found. The lowset half-wave voltage is only 76V for the PMN–0.38PT single-domain crystal. Compared to commonly used electrooptic crystal LiNbO3, tetragonal relaxor-PT ferroelectric single-domain crystals are much superior for optical modulation applications because of their much higher linear electrooptic coefficients and substantially lower half-wave voltages when the piezoelectric strain influence is considered.

X-ray diffraction measurement of residual stress in sol-gel grown lead zirconate titanate thick films on nickel-based super alloy substrate

Residual compressive stress of Pb(Zr0.52Ti0.48)O3 thick films was investigated using residual strains derived from X-ray diffraction patterns. Sin2ψ method was applied for the 5, 10 and 15 µm sol-gel derived thick films annealed at 700°C for 1 hr as high frequency structural health monitoring square-shape transducers of 10×10 mm, deposited onto the curved nickel-based super alloy substrates. A triaxial model was proposed based on piezoelectric constitutive equations, and Bragg’s law at a large diffraction angle (∼89o) was utilized considering the electromechanical coupling factor as well as elastic, dielectric and piezoelectric constants. Thickness variations led to a significant change in residual stress magnitudes delineated from more-accurate triaxial model compared to small angle plane-stress results not considering the piezoelectric coupling effects.

Transient analysis of biocomposite laminates with delamination.

The transient analysis of smart biocomposite laminates with delamination at ply interfaces is investigated, by using an electro-mechanical coupled improved layerwise theory. The piezoelectric coupling effect was modeled using higher order electric potential. Four-node plate elements were used for finite element implementation. Linear Lagrange interpolation functions were used for in-plane structural unknowns and electric unknowns, and a Hermite cubic interpolation function was used for out-of-plane structural unknowns. Single delamination was seeded in the biocomposite laminates at three different locations, to study the effects of delamination. Numerical results were obtained by using the Newmark-beta algorithm. The results showed that the time history of nodal displacement and sensor output didn't give enough information of delamination. However, the power spectral density of the time history provided clear information of the delamination effects. From the results, it is expected that the proposed theory has the potential to predict the dynamic characteristics and delamination effects in smart biocomposite laminates.