Piezoelectric Structures Research Articles

Love-type waves generated by an impulsive source in a conductive polymer-coated piezoelectric composite structure

Love-type waves generated by an impulsive source in a conductive polymer-coated piezoelectric composite structure

Effect of temperature on adhesion behavior of layered piezoelectric structure

The effect of temperature on adhesion is neglected in classical adhesive contact theories. However, an increasing number of experimental results indicate that temperature has a prominent effect on adhesion behaviors. In this study, the anisothermal adhesive contact behaviors between two transversely isotropic piezoelectric cylinders with different initial temperatures is investigated by virtue of the generalized JKR model, where the contact interface is assumed to be perfectly bonded. The considered problem is reduced to coupled singular integral equations, which is derived by using the Fourier integral transform. The closed-form solutions of anisothermal generalized stress fields are obtained by taking the series expansion of the integrand induced by temperature difference. The effect of temperature difference on adhesion behaviors of two different types of layered piezoelectric structures under the action of mechanical-electro loadings is revealed. It is found that the pull-off force and contact size at pull-off moment decrease with increasing the temperature difference. The adhesion weakening effect induced by temperature difference diminishes when the electric loading is exerted. The results derived from this paper shed lights on understanding the adhesive contact behaviors of piezoelectric materials in the presence of temperature difference.

Micro-particle aggregation using vortices induced by vibration of a piezoelectric cantilever beam-probe structure

Large-scale nondestructive aggregation of micro-particles is essential for cell detection, microplastics removal and micro- and nano pharmaceuticals. To achieve this goal, this work proposes a method by creating a vortex region in the fluid field using low-frequency oscillation of a piezoelectric cantilever beam probe structure. Vibration of the probe agitates the liquid, creating a horseshoe-shaped vortex in the fluid field. This facilitates the movement of micro-particles and traps them. Using polystyrene microspheres with a diameter of 20 µm and pollen (20–40 µm) as aggregated objects, particle agglomeration tests and flow field PIV tests are performed. Experimental results confirm that the designed structure has the best performance with a driving voltage of 100 V and a driving frequency of 72 Hz. The maximum aggregation area of polystyrene and pollen is 106956 µm2 and 234750 µm2. There are symmetrical large vortices regions on both sides of the probe and small vortices zero vorticity near the free end of the probe. It is also confirmed that small vortices are the root cause of microparticle aggregation. The aggregation method proposed in this study has advantages of low cost, non-selectivity of characteristics for controlled samples, large manipulation area and low power consumption (0.42 W).

Hydroacoustic performance analysis and testing of a novel piezoelectric material transducer

In order to address the high sensitivity requirements of underwater detection systems, this paper designs two new piezoelectric material hydroacoustic transducers, single metal plate and bimetal plate arrays, based on 1–3 piezoelectric composites. By changing the piezoelectric ceramic's original structure to improve its piezoelectric properties, the transducer's overall performance is improved. The comparison of theoretical analysis and finite element simulation results shows that the single metal plate and double metal plate array structures use air instead of polymer to reduce the loss with a higher electromechanical coupling coefficient compared with 1–3 composite materials. 1–3, mono- and bi-metal plate array structure transducers were prepared in turn and tested for hydroacoustic performance. According to the results, the double metal plate array structure has a higher electromechanical coupling coefficient, transmit voltage response, and receive sensitivity compared to the 1–3 piezoelectric composites andsingle metal plate array transducers. The maximum transmit voltage response and receive sensitivity values are 179.8 dB and −173.8 dB, respectively. The bimetallic version of the array structure transducer can be applied to underwater detection systems, which have the ability to detect weaker signals.

Nonlinear electromechanical bending of bi-modular piezoelectric laminated beams

In this paper, the nonlinear electromechanical bending of a bi-modular piezoelectric laminated beam is studied based on the principle of minimum potential energy and the Adomian decomposition method. The different tensile-compressive Young’s modulus of the core and piezoelectric layers, and the different tensile-compressive piezoelectric coefficients are considered. The electromechanical governing equations and related boundary conditions are obtained by using the principle of minimum potential energy. The deflection, neutral layer and interlaminar stresses of the beam are solved by the Adomian decomposition method and the iterative method, and verified by the finite element model and Galerkin's method. Results show that the applied voltage and the bi-modular characteristics affect the position of the neutral layer and the interlaminar stresses. Compared with the bi-modular properties of the core layer, the influences of the bi-modular properties of the piezoelectric layer on the neutral layer are relatively unobvious. In addition, the interlaminar stresses between the piezoelectric layer and core layer can be increased or decreased, depending on the relative magnitude of the applied voltage ratio and the bi-modular ratio. The results obtained are helpful for the analysis of the electromechanical coupling mechanism and design of piezoelectric composites and structures with bi-modular characteristics.

Optimal Placement and Active Control Methods for Integrating Smart Material in Dynamic Suppression Structures

To simulate a lightweight structure with integrated actuators and sensors, two-dimensional finite elements are utilized. The study looks at the optimal location and active vibration control for a piezoelectric smart flexible structure. Intelligent applications are commonly used in engineering applications. In computational mechanics, selecting the ideal position for actuators to suppress oscillations is crucial. The structure oscillates due to dynamic disturbance, and active control is used to try to reduce the oscillation. Utilizing an LQR and Hinfinity controller, optimization is carried out to determine the best controller weights, which will dampen the oscillation. Challenging issues arise in the design of control techniques for piezoelectric smart structures. Piezoelectric materials have been investigated for use in distributed parameter systems (for example airplane wings, intelligent bridges, etc.) to provide active control efficiently and affordably. Still, no full suppression of the oscillation with this approach has been achieved so far. The controller’s order is then decreased using optimization techniques. Piezoelectric actuators are positioned optimally according to an enhanced optimization method. The outcomes demonstrate that the actuator optimization strategies used in the piezoelectric smart single flexible manipulator system have increased observability in addition to good vibration suppression results.

Size-dependent coupled bending-torsional analysis of piezoelectric micro beams

Nowadays, piezoelectric micro-beam structures are used in various industries, and knowing and analysis of these smart microstructures is important. However, in the modeling of these electromechanical microbeams, the torsion during bending is generally omitted for simplicity. Considering that in some cases, twisting and bending cannot be omitted and must be modeled simultaneously. Therefore, this article presents a coupled bending-torsion model for the first time for static deflection and free vibration analysis of piezoelectric microbeams with nonclassical continuum theories. The governing equations of the motion and boundary conditions of the Timoshenko beam at the micro-scale have been obtained using size-dependent electromechanical theory and Hamilton’s principle. In addition, the Laplace transform is used to solve the static equations, while the generalized differential quadratic (GDQ) method is used to discretize and solve the free vibration equations. In the following, the influence of various parameters, such as the effect of size and geometric conditions, on the static displacements and the natural frequency of the microbeam is discussed.

Fabrication of Piezoelectric Structures with High Porosity by Digital Light Processing

Fabrication of Piezoelectric Structures with High Porosity by Digital Light Processing

ZnO@ZIF-8: The construction of core-shell structures to a new reaction pathway for efficient TC degradation

Present situation of tetracycline antibiotic pollution in water bodies is serious. In this study, ZnO@ZIF-8 with core-shell and non-central symmetric piezoelectric material structure was synthesized by mechanochemical method, which exhibits excellent degradation properties: degradation rate of a 50 mg/L tetracycline solution after 40 min of vibration can exceed 90%. Experimental analysis has confirmed that the composite material has better piezoelectric performance. Additionally, the adsorption of pollutants by ZIF-8 can effectively shorten the reaction path, which breaks through the limitations of general solution reactions, thereby improving the catalytic reaction efficiency. Radical quenching and electron paramagnetic resonance results have demonstrated that ∙OH and ∙O2– are the main active radicals of the catalytic reactions in the solution. Finally, the study identified the products after tetracycline degradation. This work provides a fresh approach to the application of piezoelectric materials in sewage treatment.

Analysis of the characteristics of valveless piezoelectric pump with crescent dune bluff body.

To improve the output flow characteristics of the piezoelectric pump in one direction, a new valveless piezoelectric pump with a crescent dune bluff body has been proposed. The pump can achieve low damage to the active substance on the premise that the active cell can guarantee the transport volume. By comparing with the hemispherically deficient and imitated meniscus resistance fluid, the barchan dune resistance fluid which can effectively improve the unidirectional output of the piezoelectric pump is obtained. Combined with the pump theoretical flow calculation formula, these influencing parameters, the degree of inclination, the sand ridge radius and the order of the crescent dune were analyzed. Finally, an experimental prototype of a valveless piezoelectric pump has been fabricated by 3D printing technology, and the pump flow test is being conducted. The relationship between frequency, voltage and output flow has been obtained. The test results show that with a dune inclination of 37.5, a sand ridge radius of 6.75 mm and a dune order of 4, the flow rate of the piezoelectric pump is best at 194.7 mL/min. The experimental results agree with the simulation results, showing the effectiveness of the valveless piezoelectric pump structure.

Thermo-electro-elastic coupled modeling and simulation of functionally graded piezoelectric structures

Compared with the composite materials, the functionally graded materials can not only provide better specific stiffness but also reduce the risk of layered damage. Therefore, the graded distribution forms have become the development trend of advanced structures. An efficient finite element (FE) modeling method and numerical simulation of plate and shell with nonlinear temperature gradient coupling are developed based on the FOSD hypothesis for thermo-electro-elastic coupled functionally graded piezoelectric material (FGPM) integrated with smart structures in this paper. The constitutive model for thermo-electro-elastic coupled FGPM is derived. Assuming that the temperature gradient distribution changes secondarily through the thickness, two nonlinear physical models for temperature change are constructed. Based on the FOSD hypothesis, the multi-field coupled FE equation of plate and shell is derived. The accuracy of the present FE model is verified by the commercial calculation structures. The parametric simulation of FGPM shells is carried out based on the FE model.

A piezoelectric wave energy harvester equipped with a sequential-drive rotating mechanism and rotary piezoelectric harvesting component

This study developed a sequential rotary-driven piezoelectric wave energy harvester (SRD-PWEH), comprising a cylindrical buoy, sequential-drive rotating mechanism based on a pair of one-way bearings, and rotary piezoelectric harvesting component. The harvesting component was based on a circumferentially arranged piezoelectric composite cantilever beam array. The one-way bearings converted the repetitive rotary motion of an input shaft into a unidirectional rotational motion without reverse rotation to drive the rotary piezoelectric harvesting component. Considering that the rotary-driven process is kind of noncontact-driven, it can effectively reduce the risk of damage to the piezoelectric composite cantilever beam structure. The SRD-PWEH was tested in a wave flume under two wave amplitudes and five wave periods. Results showed that the experimental condition of the wave amplitude and period of 75 mm and 0.9 s, respectively, achieved the highest electrical power. The root-mean-square voltage and maximum average power with the fault diagnosis rate filter circuit were 2.46 V and 0.49 mW, respectively.

Developments in the Use of Hinfinity Control and μ-Analysis for Reducing Vibration in Intelligent Structures

During the past few years, there has been a notable surge of interest in the field of smart structures. An intelligent structure is one that automatically responds to mechanical disturbances by minimizing oscillations after intelligently detecting them. In this study, a smart design that contains integrated actuators and sensors that can dampen oscillations is shown. A finite element analysis is used in conjunction with the application of dynamic loads such as wind force. The dynamic-loading-induced vibration of the intelligent piezoelectric structure is aimed to be mitigated using a μ-controller. The controller’s robustness against uncertainties in the parameters to address vibration-related concerns is showcased. This article offers a thorough depiction of the benefits stemming from μ-analysis and active vibration control in the behavior of intelligent structures. The gradual surmounting of these challenges is attributed to the increasing affordability and enhanced capability of electronic components used for control implementation. The advancement of μ-analysis and robust control for vibration reduction in intelligent structures is amply demonstrated in this study.

Nanoindentation response of small-volume piezoelectric structures and multi-layered composites: modeling the effect of surrounding materials

With piezoelectric small-volume composites gaining importance in smart device applications and nanoindentation being recognized as a versatile method for assessing the properties of layer materials, the present study is focused on the indentation response of the small-volume piezoelectric structures multi-layered composites. In particular, the effects of the nature of the substrate and surrounding materials, on the indentation response of piezoelectric nanocomposites, such as nanoislands, nanowires, and multi-layered composites are investigated. By developing three-dimensional finite element modeling, the complex interaction between the fundamental elastic, piezoelectric and dielectric properties of the piezoelectric materials and the elastic, plastic and electrically conducting or insulating properties of the surrounding materials, on the indentation response of the layered composites is analyzed. It is found that: (i) a substrate material that is elastically stiffer enhances the mechanical indentation stiffness and the electric indentation stiffness while plastic deformation in the substrate causes a reduction in the mechanical and electrical indentation stiffness; (ii) the effective piezoelectric and mechanical indentation stiffnesses of piezoelectric multi-layered composites are bounded by the corresponding characteristics of the bulk material counterparts from which the individual layers are constructed; (iii) electrically conducting surrounding materials produce a softening effect while insulating materials enhance the electrical indentation stiffness resulting in more charges being accumulated during the indentation process.

Nonlinear model order reduction of resonant piezoelectric micro-actuators: An invariant manifold approach

This paper presents a novel derivation of the direct parametrisation method for invariant manifolds able to build simulation-free reduced-order models for nonlinear piezoelectric structures, with a particular emphasis on applications to Micro Electro Mechanical Systems. The constitutive model adopted accounts for the hysteretic and electrostrictive response of the piezoelectric material by resorting to the Landau-Devonshire theory of ferroelectrics. Results are validated with full-order simulations operated with a harmonic balance finite element method to highlight the reliability of the proposed reduction procedure. Numerical results show a remarkable gain in terms of computing time as a result of the dimensionality reduction process over low dimensional invariant sets. Results are also compared with experimental data to highlight the remarkable benefits of the proposed model order reduction technique.

Effect of strontium substitution on growth and piezoelectric properties of calcium magnesium silicate Ca2MgSi2O7 single crystals

We report the effect of Sr substitution on the crystal growth and piezoelectric properties of calcium magnesium silicate Ca2MgSi2O7 (CMS) single crystals. Strontium-substituted CMS single crystals with a chemical composition of Ca1−x Sr x MgSi2O7 (CSMS100x; x = 0.0 to 0.6) were grown using the conventional Czochralski method. CSMS100x crystals without impurity phases are obtained up to x = 0.5. Both crystallographic axis c and a increased with the Sr content x, and the crystallographic axis ratio a/c decreased. The piezoelectric d 36 constants obtained using CMS, CSMS30, and CSMS40 crystals decreased with an increase in the Sr content x. Based on these observations, a relationship between piezoelectric properties and crystal structure was found using data from 14 types of melilite-type crystals. It was found that d 36 increases with an increase in a/c.

Effect of bismuth deficiency with K substitution for Na on piezoelectric properties and crystal structure of Bi0.5−x(Na0.8−yK0.2+y)0.5TiO3–3x/2 (0 ≤ x ≤ 0.015, 0 ≤ y ≤ 0.1) ceramics

The piezoelectric properties and crystal structure of Bi0.5−x(Na0.8−yK0.2+y)0.5TiO3–3x/2 (0 ≤ x ≤ 0.015, 0 ≤ y ≤ 0.1) ceramics were characterized in this study. The crystal-structure refinement for Bi0.5−x(Na0.8K0.2)0.5TiO3–3x/2 was carried out using synchrotron X-ray diffraction data and Rietveld analysis and revealed the coexistence of rhombohedral (R3c) and tetragonal (P4mm) phases for the compositions with 0 ≤ x ≤ 0.015, although the fraction of these phases was almost independent of the composition x (49% for the rhombohedral phase and 51% for the tetragonal phase at x = 0.015). The Bi deficiency led to an increase in the lattice distortion of rhombohedral phase and a decrease in the that of tetragonal phase. The piezoelectric constant (d33) value decreased from 151.5 to 120.6 pC/N as x was increased from 0 to 0.015, and a shift of the depolarization temperature to higher temperatures was also confirmed by in situ d33 measurements. These results are attributed to an increase in the lattice distortion of rhombohedral phase enhanced by the Bi deficiency. The K substitution for Na in Bi0.485(Na0.8−yK0.2+y)0.5TiO2.9775 led to the formation of a morphotropic phase boundary (MPB) in the composition range 0 ≤ y ≤ 0.06, resulting in an increase in the fraction of the tetragonal phase. Although a decrease in the mechanical quality factor (Qm) was observed for K-rich compositions, the highest d33 value of 195.4 pC/N with a mechanical coupling factor of 32.9% was obtained for the Bi0.485(Na0.76K0.24)0.5TiO2.9775 (y = 0.04) ceramic because of the enhancement of the tetragonality in the MPB region, resulting in the onset of depolarization at ∼170 °C.

A piezoelectric–electromagnetic hybrid energy harvester inspired by flapping motion of the Diptera insect

Low-frequency vibration is widespread in nature. Vibration energy harvesting is considered to be a reliable and sustainable method to achieve continuous power supply. It is a feasible method to design an energy harvesting system of the bio-inspired mechanical structure to improve the efficiency of energy harvesting. A hybrid energy harvester piezoelectric–electromagnetic that mimics the flapping wing motion of the Diptera insect. The biomimetic energy harvesting device consists of two piezoelectric cantilever beams structure with the mass block installed, which mimics the flapping movement mechanism of the Diptera insect. The intermediate part of this harvester inspired by the insect skeleton and muscle structure of the Diptera insect is composed of magnetic levitation coupled repulsion structure, which is easily affected by vibration and changes greatly, to realize electromagnetic energy harvesting. The ‘click’ mechanism of the Diptera insect is constructed by storing energy in springs to improve the performance of energy harvesting devices. The hybrid energy harvesting device realizes piezoelectric–electromagnetic energy harvesting with multiple energy outputs at one excitation input. A dynamic model of the proposed energy harvester is constructed based on the electromechanical coupling characteristics. The modal analysis and structure optimization of this device is realized by the finite element method (FEM). The FEM simulation and experimental results can verify that under the low-frequency excitation of 3 Hz, the maximum output power of the designed harvester reaches 12.33 mW in the low-frequency environment.

Harnessing ultrasound in photocatalysis: Synthesis and piezo-enhanced effect: A review

The photocatalytic technique has drawn far-ranging interests in addressing the current issues; however, its property suffers from the limited visible light response and rapid recombination of carriers. To address these issues, two specific approaches have been proposed to enhance the photocatalytic activity: (1) ultrasound-assisted synthesis has been utilized to prepare photocatalysts, resulting in refined grain size, increased specific surface area, and reduced photogenerated carrier recombination; (2) sonophotocatalysis and piezoelectric enhanced photocatalysis have been developed to accelerate the reaction, which utilizes the synergism between ultrasound and light. On one side, sonophotocatalysis generates cavitation bubbles which induce more reactive radicals for redox reactions. On the other side, ultrasound induces deformation of the piezoelectric material structure, which changes the internal piezoelectric potential and improves the photocatalytic performance. Currently, intensive efforts have been devoted to related research and great progress has been reached with applications in pollutant degradation, new energy production, and other fields. This work starts by elucidating the fundamental concept of ultrasound-assisted photocatalyst synthesis and photocatalysis. Then, the synergistic behavior between ultrasonic and light in ultrasonic-assisted photocatalysis has been thoroughly discussed, including pollutant degradation, water splitting, and bacterial sterilization. Finally, the challenge and outlook are investigated and proposed.

Field experiments of watt-level piezoelectric energy harvester for different embedded depths

Road piezoelectric energy-harvesting technology uses the positive piezoelectric effect to convert vibrational energy produced by vehicular load to electrical energy. Road piezoelectric energy harvesters (RPEHs) are the core elements behind this technology. A new disc-type metal–piezoelectric ceramic transducer structure was developed to promote road piezoelectric energy collection and increase power generation from RPEHs. Finite element analyses and field tests were then conducted. The experimental results show that the disc transducers have excellent road compatibility. The greater the embedded depth of the transducer, the smaller is the output power of the RPEH; hence, an embedded depth of 2 cm was selected as the optimal value for comprehensive durability and electrical performance. When a small car travelling at a speed of 60 km/h passed over the RPEH embedded at a depth of 2 cm, a maximum voltage of 62 V, maximum current of 62 mA, and maximum utput power of 3844 mW (power density: 43 W/m2) were observed. The influence of the vehicle weight on the RPEH output power decreased with increase in speed. Therefore, this study confirms that the new disc-type RPEH is less costly, has excellent power generation, and requires less piezoelectric transducer material.