Piezo Patches Research Articles

Experimental investigations of the effects of bending vibrations resonance modes on penetration into granular materials

Inspired by the bending vibration observed in the biological locomotions such as those found in snakes, horned lizards, and sandfish, we have developed a novel vibro probe utilizing bending resonance modes to study the bending vibration effects in assisting penetration into granular materials. This approach contrasts with traditional probes that rely on longitudinal vibrations for penetration. This newly developed probe was used to experimentally investigate the impact of bending vibration in reducing the required penetration force and enhancing the penetration process within granular materials such as lunar or Martian regolith. The bending vibrations were excited by thin piezo patches attached to the probe’s machined surface without increasing the probe’s outside diameter. This simple mechanism enables pushing the whole probe inside the granular materials. Experimental modal analysis was employed to determine the resonance frequencies of the probe. Subsequently, the probe was pushed into granular materials, both with and without the bending vibrations, by a linear actuator. Experimental results indicated that employing bending vibration in one direction led to a reduction in penetration force by up to 27% while utilizing two directions resulted in a reduction of up to 42%. Additionally, when the probe stopped penetrating the soil due to insufficient axial force, bi-directional bending vibration proved more effective in swiftly fluidizing the surrounding soil. These findings highlight the efficacy of bending vibrations in compact subsurface drilling tools.

Experimental study on the piezo-based energy harvester utilizing the ambient vibrations for smart applications

The proposed energy harvester has novel construction, its performance evaluated through frequency response, force response and power harvested under an optimum load, is presented. This harvester is more suitable for low power applications like IoT devices, Wireless sensor nodes and biomedical implants. The suggested harvester has two sections namely truncated cone and rectangular beam section (TCRB). The analytical model is formulated and natural frequencies are obtained using FEA tool. Simulations for natural frequencies and associated comprehensive parameters are done along with distribution of stress across the piezo patch. The tapered radius ratio of the truncated cone is analysed to obtain the optimal value. The simulated model is fabricated and verified experimentally. The result is compared with uniform cantilever beam harvester. The voltage produced by a TCRB harvester is 56.76 % higher than the harvester with a homogeneous rectangular cantilever beam. The rectangular harvester has a resonant frequency of 52.8 Hz, while the TCRB harvester has 39.4 Hz. Also, the TCRB type piezoelectric vibration energy harvester with optimum taper radius ratio provides greater power, than uniform and trapezoidal cantilever beams. The obtained experimental results match the simulation results, ascertains the validity of the proposed harvester.

An analytical analysis of vibrational energy harvesting using piezoelectric energy harvester in a fixed wing unmanned aerial vehicle

Fixed-wing unmanned aerial vehicles (UAVs) in the modern day have widespread applications in various reconnaissance, agriculture, military, and civilian operations. Their wide domain of application has placed the development of drone technology at the forefront. The energy harvesting in UAVs seems promising since it not only has the ability to lengthen flying time but also guarantees that no appreciable weight is added. The current article explores the concept of placing piezoelectric material patches on the UAV wing in order to extract energy from the vibration of the wing. This study uses a UAV's fixed NACA 2412 wing to harvest vibration energy by finding the location and placing a piezoelectric patch where it will produce the most voltage. The mode shapes generated are used to get the appropriate location to place the piezoelectric patch. The fixed-wing of a UAV with a piezo patch placed is subjected to a harmonically varying pressure load of 213.934 Pa and the behavior of the wing and its frequency response is analyzed in terms of displacement and voltage as output. The maximum voltage produced by the single piezoelectric patch is found about 0.11 V at the first mode shape of the wing. Embedding and increasing the patch at a location of high displacements help to harvest more energy and can be utilized for other purposes.

A novel approach for synchronized switch damping control based on voltage sources in parallel

This paper presents a novel hybrid model, termed Synchronized Switch Damping with Voltage Sources in Parallel (SSDVP), for enhancing the performance of synchronized switch damping (SSD) control by addressing the flipping voltage and voltage drop issues in piezoelectric elements. The effectiveness of SSD control is closely related to the voltage applied to the piezoelectric element. However, at high voltages, such as the maximum capacity of 1.5 kV for piezoelectric materials, charge leakage becomes significant and cannot be ignored. This results in substantial voltage drop during switching intervals, particularly in low-frequency applications. The proposed SSDVP method combines the advantages of SSDI and Bang-bang control to generate a stable high voltage across the piezoelectric element with minimal power consumption. The working principle and mathematical model of the SSDVP method are described, including the expression of the voltage across the piezo patch and the energy consumption of the control circuit. Simulation and experimental comparisons are conducted among the traditional SSDV model, Bang-bang control, and the proposed SSDVP model to demonstrate the advantages of the novel approach.

Analysis of smart laminated composites integrated with piezoelectric patches using spectral element method and lamination parameters

This paper investigates the effect of stacking sequence on the power output of a smart composite panel integrated with piezoelectric patches, using lamination parameter formulation and spectral element method (SEM). The deformation of the panel is expressed using the first-order shear deformation theory. The strain energy of the host plate is formulated using lamination parameters and the governing equations are derived following Hamilton’s principle. To solve the governing equations accurately and efficiently, a spectral element method is applied where the structure is divided into regions that are continuous in terms of geometry, and element matrices of each region are calculated using the spectral Chebyshev approach. This method benefits both from the (geometry) flexibility of the finite element method and the accuracy of the meshless methods. The developed electromechanical model is used to study the effect of the number of piezo patches and their sizes. To demonstrate the accuracy and performance of the presented SEM, six case studies were investigated by comparing natural frequencies, structural/voltage frequency response functions (FRFs), and computational duration to those obtained from a finite element analysis (FEA). The maximum difference in the predicted natural frequencies between the SEM and FEA results is below 1% and the FRFs obtained using the presented solution technique excellently match the FEA results. Yet, the simulation duration is significantly reduced compared to FEA. To exploit the computational efficiency of the presented analysis approach, optimization case studies were also performed implementing a genetic algorithm to maximize the power output by optimizing the stacking sequence and patch distribution.

Monitoring hydration of concrete using EMI of surface bonded smart piezo patches

Monitoring hydration of concrete using EMI of surface bonded smart piezo patches

Comparison of Structural Integrated Piezoceramics, Piezoelectric Patches and Strain Gauges for Condition Monitoring.

This paper presents a new approach to the structural integration of piezoceramics into thin-walled steel components for condition-monitoring applications. The procedure for integrating the sensors into metal components is described, and their functionality is experimentally examined with a 2 mm-thick steel sheet. The signal quality of the produced sensors is investigated in a frequency range from 100 Hz to 50,000 Hz and is compared with the results of piezo patches and strain gauges under the same conditions. The results show that due to a higher signal-to-noise ratio and a better coherence, the structurally integrated piezoceramics and the piezo patches are more qualified sensors for vibration measurement in the examined frequency range than the strain gauges. The measurements also indicate that the patches provide higher amplitudes for the frequency range up to 20 kHz. Beyond that, up to 40 kHz, the integrated sensors supplied higher amplitudes. The better signal quality in different frequency ranges as well as the different manufacturing and application methods can be interpreted as an advantage or disadvantage depending on the boundary conditions of the condition-monitoring system. In summary, structural integrated piezoceramics extend the options of monitoring technology.

Auxetic hexachiral cantilever beams for piezoelectric vibration energy harvesting

This work presents an auxetic hexachiral cantilever substrate for low-frequency vibration energy harvesting applications. Auxetics are materials with negative Poisson’s ratio that develop stresses of the same nature under mechanical loading, which can be advantageously used in designing energy harvesters with enhanced power output. The proposed harvester is fabricated by attaching a piezo patch on a 3D printed polylactic acid hexachiral substrate to convert the mechanical response to electrical output. Experiments are conducted to characterize the vibration and electrical properties of the harvester. A 3D finite element (FE) model is developed and validated with experimental voltage obtained for different electrical resistance. As the first mode generates maximum power, an equivalent single degree of freedom semi-analytical model is formulated and validated with experiments and FE results. The proposed harvester has a natural frequency of 23 Hz with a voltage output of 9.1 V at 250 kΩ. The developed models are used to study the influence of hexachiral geometry, electrical and mechanical loading on the electro-mechanical response. The harvester voltage is influenced by the ligament thickness and is found to increase linearly with an increase in mechanical loading. Further, the enhancement in performance by the addition of hexachiral sub patch to a plain beam is investigated, followed by a comparison with harvesters having plain, hexagonal and re-entrant geometries. The results show that the hexachiral harvester has the lowest first mode frequency with a power output about 20 and 3 times the plain and re-entrant harvesters, respectively. Finally, random vibration analysis of the hexachiral harvester is carried out to evaluate its performance under ambient loading, and the results show that the semi-analytical model is a computationally efficient alternative to study the first mode behavior. The findings of the study demonstrate the potential of the proposed hexachiral harvester for low-frequency applications.

Nelinearna strategija kontrole pametnih tankih ploča sa kubnom nelinearnostima primenom tehnike aproksimacije funkcijama (TAF)

The current work introduces three nonlinear control solutions for the regulation of a vibrating nonlinear plate considering model uncertainty. These solutions are feedback linearization control (FBL), virtual velocity error-based control (VVEC), and backstepping control (BSC). In the FBL control, a nonlinear control law is designed with linear closed-loop dynamics such that dynamic stability is ensured. Whereas, by the VVEC (or so-called passivity-based approach in the robotics community) the limitations of the feedback linearization are overcome. On the other side, the BSC selects virtual control variables with stabilized intermediate control laws based on Lyapunov theory. Systematic modeling for the target vibrating plate with piezo patches is described. In effect, considering the nonlinear influence makes the resulted mode shapes for the vibrating structure are highly coupled and careful control design is required. Using the Galerkin approach, the partial differential equation for the smart plate is transformed into definite ordinary differential equations; the multi-input multi-output model is established. The aforementioned control strategies are evaluated and investigated in detail. In essence, they are powerful tools for dealing with nonlinear dynamic systems, however, the VVEC could be considered superior in comparison with the FBL control and the BSC since the designed control structure does not include inertia inverse matrix and modal coordinate acceleration that could make computational problems. As a result, simulation experiments were focused on the VVEC strategy, and the latter was implemented on a simply supported thin plate structure with collocated piezo-patches. The results show the validity of the proposed control architecture.

Towards Localized Tactile Feedback on Touch Surfaces: Finite Element Analysis of a Vibrating Touch Screen Actuated by Piezo Patches

Surface haptics technologies offer an augmented user experience by providing a unique and distinctive interaction between the finger and touchscreen. In this study, we focus on a touch screen design to display vibrotactile tactile feedback to the user through piezo patches located on its surface. We investigated the effects of boundary conditions, piezo configurations, and materials of the touch surface and piezo patches that will achieve the highest deformation on the touch surface, considering the most sensible human tactile perception frequency using the ANSYS FEM software package. In our analysis, we used three different touch surface and piezo patch materials, three different boundary conditions, four different piezo patch locations, and three different touch surface thicknesses. The results showed that the boundary conditions and thickness of the glass have a significant effect on the first natural frequency of the touch surface, and the results leading to best human tactile perception were obtained by fixing four piezo patches at four sides of the touch surface. Based on the determined configuration in the modal analyses, we performed a response surface optimization study to estimate the geometry of the touch surface (width, height, thickness), which will result in maximum deformation on the touch surface. We achieved the best configuration (max total deformation at about 250 Hz first modal frequency) with 160 × 90 × 0.28 mm and 190 × 110 × 0.4 mm dimensions. In the future, we will develop models to render localized tactile feedback on a touchscreen-based on piezo patches operating at various combinations (i.e., sequence, amplitude, frequency), which will be predicted based on the FEM simulations.

Piezo-based flexural vibration suppression for an annular rotor via rotating-frame H2 control optimization

Elastic vibration can arise in annular and thin-walled rotor structures, impacting on operating performance and the risk of failure. Feedback control to reduce flexural vibration can be realized using lightweight actuators and sensors embedded in the rotor structure. To design optimal controllers, rotating-frame models of both the structural dynamics and sources of excitation are required. This paper describes a solution to this problem for the case of an annular rotor equipped with piezo patch actuators and sensors. To account for space-fixed external excitation sources, a forcing function is considered involving specified spatial and frequency domain distributions. A model-based [Formula: see text] synthesis is used to compute optimal control solutions. These are tested experimentally on a thin-walled cylindrical steel rotor for cases with narrowband and broadband excitation sources, applied from the fixed frame. The results show that frequency-splitting within the rotating-frame dynamics plays a key role in predicting and controlling resonance. The effectiveness of the optimal control methodology in reducing circumferential vibration of the annular rotor is also confirmed.

Mini-max optimization of actuator/sensor placement for flexural vibration control of a rotating thin-walled cylinder over a range of speeds

For a rotating thin-walled cylinder subject to flexural vibration, active control can be applied using surface-mounted actuators and sensors. To achieve acceptable vibration control performance, the dependency of the dynamic behaviour on rotational speed must be accounted for in the control system design, including the selection and positioning of actuators and sensors. A key issue is that the natural modes of vibration of the cylinder wall involve circumferential travelling waves and, for certain rotational speeds, the frequency of a backward wave for a low order mode can become equal to that of a forward wave for a high order mode. It is shown that these frequency-crossings have important implications for the actuator/sensor placement problem due to the potential for loss of controllability. Accordingly, an actuator/sensor placement approach is introduced based on a mini-max optimization, where the system controllability is maximized for the worst-case rotational speed within a specified interval. Placement solutions are obtained through the application of a nested particle swarm optimization algorithm, used to find saddle-point solutions. The approach is shown to be effective for cases involving 2, 3 and 4 actuator/sensor pairs and with multi-mode model (including up to 16 modes). The results are confirmed by experiments on a thin-walled rotor system with piezo patch actuators and sensors, where H2 control algorithms are applied to suppress vibrational resonances within a control bandwidth of 200-1200 Hz. The potential for loss of controllability at certain rotational speeds is confirmed, as well as the effectiveness of the optimal placement solutions in maintaining control performance over a targeted range of speeds.

Performance Evaluation of a Vortex Induced Piezoelectric Energy Converter (VIPEC) with CFD Approach

A novel vortex induced piezoelectric energy converter (VIPEC) was present in this paper to harvest flow kinetic energy from the ambient environment through a piezoelectric beam. The converter consists of a circular cylinder, a pivoted beam attached to the tail of the cylinder and several piezoelectric patches. Vortex induced pressure difference acts on the beam and drives the beam to squeeze piezo patches to convert fluid dynamic energy into electric energy. Transition Shear Stress Transport (SST) combined with Scale Adaptive Simulation (SAS) model was employed to predict the turbulent flow and flow separation around the cylinder with various beam lengths at high Reynolds number of 8 × 104 based on the computational fluid dynamics (CFD) approach. The accuracy of SST-SAS model was investigated through verification and validation studies. The output voltage equation was derived from the piezoelectric constitutive equation. It was revealed that the beam length influences the flow wake pattern, the separation angle and shedding frequency greatly through changing the adverse pressure gradient around the cylinder. The wake pattern becomes symmetrical about the beam when the beam length is longer than a critical value. The length of the beam has little influence on the separation angle. When the beam length is about 1.3 times the diameter of the cylinder, the shedding frequency and output voltage achieves its maximum, and the separation angle is minimal. Maximal output voltage reaches 20 mV.

Design and Performance Evaluation of a "Fixed-Point" Spar Buoy Equipped with a Piezoelectric Energy Harvesting Unit for Floating Near-Shore Applications.

In the present work, a spar-buoy scaled model was designed and built through a “Lab-on-Sea” unit, equipped with an energy harvesting system. Such a system is based on deformable bands, which are loyal to the unit, to convert wave motion energy into electricity by means of piezo patch transducers. In a preliminary stage, the scaled model, suitable for tests in a controlled ripples-type wave motion channel, was tested in order to verify the “fixed-point” assumption in pitch and roll motions and, consequently, to optimize energy harvesting. A special type of structure was designed, numerically simulated, and experimentally verified. The proposed solution represents an advantageous compromise between the lightness of the used materials and the amount of recoverable energy. The energy, which was obtained from the piezo patch transducers during the simulations in the laboratory, was found to be enough to self-sustain the feasible on-board sensors and the remote data transmission system.

Vibration Modelling and Control Experiments for a Thin-Walled Cylindrical Rotor with Piezo Patch Actuation and Sensing

This paper describes a dynamic model formulation and control experiments concerning the vibration behaviour of a thin-walled cylindrical rotor with internal piezoelectric patch transducers. Model development, validation and controller design procedures were undertaken for an experimental rotordynamic system comprising a tubular steel rotor (length 0.8 m, diameter 0.166 m and wall-thickness 3.06 mm) supported by two radial active magnetic bearings. Analytical solutions for mode shapes and natural frequencies for free vibration were first derived using a shell theory model, and these used to construct a speed-dependent parametric model for the rotor structure, including piezo patch actuators and sensors. The results confirm that the developed shell theory model can accurately capture the rotating frame dynamics and accounts correctly for frequency splitting from Coriolis effects. The model is also shown to be suitable for active controller design and optimization. Model-based H2 feedback control using the rotor-mounted actuators and sensors is shown to achieve vibration suppression of targeted flexural modes, both with and without rotation.

A distributed-parameter electromechanical coupling model for a piezoelectric energy harvester with variable curvature

Enabling technologies for harvesting ambient vibration energy have attracted considerable attention in research communities from different disciplines in the last decades. Among the various devices, straight cantilever-based energy harvesters have been widely investigated from the perspective of designs, modeling, simulation and experiments. In this study, we propose curved piezoelectric energy harvesters (PEHs) with variable curvature to further broaden application scenarios. Within the framework of the Euler–Bernoulli beam theory, we develop a distributed-parameter electromechanical coupling model for a curved segmented unimorph with variable curvature by Hamilton’s Principle and solve it using the Rayleigh–Ritz method. The convergence and accuracy of the model are validated by finite element simulation and experiments. Based on the proposed model, we perform a systematic parameter study and discuss the effects of the proof mass, Young’s modulus of the substrate, the thickness ratio of the substrate to the total thickness, the curvature of the substrate and the piezo patch on the mechanical and electrical responses of the structures. The theoretical model will help engineers to design and optimize new PEHs and serve as a benchmark solution for future research in this field.

Design and experimental study of rotary-type energy harvester

A rotary-type energy harvester for the applications having space restrictions has been designed and developed to harvest the energy from rotary motion system. The rotation kinetic energy is converted into electrical energy through a lead zirconate titanate patch, which is strained by magnetic force. Most of the researchers used d31 mode of the piezoelectric material of such conversion. Some researchers have explored d33 mode harvester with piezo patch along the circumferential direction. In this article, d33 mode of harvesting with radial direction piezo patch has been proposed. Mathematical and finite element models are developed to calculate the harvested energy. The results are experimentally verified. The average output power of 14.48 nW is generated corresponding to the magnetic force of 0.3126 N and rotational speed of 2100 r/min. The results from the mathematical and finite element models are observed to be consistent with the experimental results. Such harvester will be useful for the applications having space limitations such as self-power generation in an artillery shell and rotary projectile.

Analytical and Experimental Studies of Double Elastic Steel Sheet (DESS) Vibration Energy Harvester System

This study provides a double elastic steel sheet (DESS) piezoelectric energy harvester system, in which the vibration generated by the deformation and clap of two elastic steel sheets is assisted by a piezo patch to generate electric energy. The system is combined with energy storage equipment to propose a complete solution forgreen energy integration. This study buildsexperimentallyon the model of the proposed system to explore its voltage, power output and energy collection efficiency. This study also builds atheoretical model of a nonlinear beam with the piezo patch, including the piezoelectric coupling coefficient and current equation. This nonlinear problem is analyzed by the method of multiple scales (MOMS). The system frequency response wasobserved using fixed points plots. The perturbation technique and numerical method wereused to mutually validate the experimental results; the concept of DESS vibration energy harvester (DESS VEH) is proved feasible. In order to prolong the lifetime of the clapping of DESS piezo patch, a camber protector design is proposed. The findings show that the power-generating effect is best when the piezo patch is placed at the peak of the third mode of the DESS system, and the high camber protector is used to generate electric energy.

Piezoelectric vortex induced vibration energy harvesting in a random flow field

Vibration-based energy harvesters have significant potential for sustainable energy generation from ambience for micro-scale systems like wireless sensor networks and similar low power electronic devices. Vortex-induced vibration (VIV) is one of the richest sources for such power generation for devices installed within a fluid environment. However, uncertainty in the direction and magnitude of the free stream velocity could affect the performance of such systems. We have first developed the mathematical model of a piezoelectric cantilever beam with end mass vibrating under the influence of VIV. The piezo patch is assumed to be in the unimorph and bimorph configurations. From the unimodal dynamic response of the system, an equivalent single degree of freedom mechanical model is developed. This is further integrated with the electrical model of the piezoelectric system without and with an inductor. The energy harvested from the deterministic harmonic excitation is estimated against the non-dimensional velocity parameter. A random process model is developed considering the excitation force due to vortex shedding to be a bounded, weakly stationary and narrowband random process. The power spectral density of the random process is obtained using the Fourier transform of the auto-correlation function. The dynamic response of the energy harvester is obtained against such random excitations. The expressions of the mean power are obtained in closed-form corresponding to the cases without and with the inductor integrated to the electrical circuit. It is observed that while for cases without the inductor, the average harvested power monotonically decreases with increase in damping ratio and decrease in the coupling factor; for models with the inductor, an optimal inductor constant exists corresponding to the maximum mean-power condition. The extensive analytical modelling and initial representative results are expected to pave the way for the practical design of VIV based piezoelectric energy harvesting system subjected to stochastic excitation.

Investigations on state estimation of smart structure systems

This paper aims at enlightening the properties, computational and implementation issues related to Kalman filter based state estimation algorithms and sliding mode observers, by applying them for estimating the states of a smart structure system. The Kalman based estimators considered in this work are Kalman filter and information filter and, the sliding mode observers considered are Utkin observer and higher order sliding mode observer. A fourth order linear time invariant model of a piezo actuated beam is used in this work. This structure is embedded with four number of piezo patches, of which two act as sensors, one as disturbance actuator and the other as control actuator. The performance of the state estimation algorithms is evaluated through simulation, for the first two vibrating modes of the piezo actuated structure, when the structure is maintained at first mode and second mode resonance.