Piezoceramic Patches Research Articles

Experimental investigation on interfacial defect detection for SCCS with conventional and novel contact NDT techniques

In order to ensure the mechanical performance and structural safety of steel–concrete composite structures (SCCS), advanced nondestructive testing (NDT) technique for bonding status at steel–concrete interfaces needs to be developed. In this study, the feasibility of multichannel analysis of surface waves (MASW)-based interfacial debonding detection is validated using the contact sensors array. Herein, the multichannel sensor arrays are composed of piezoceramic lead zirconate titanate patches and high-frequency acceleration meters, respectively. For comparison, the impact-response (IR) method and impact-transmission (IT) method are performed utilizing a force hammer and high-frequency acceleration meters, and corresponding damage imaging algorithms are developed. The applicability of ultrasonic computed tomography (CT) scanning test, scanning impact echo (IE) method, ultrasonic tomography (UT) technique on interfacial debonding detection is further discussed in depth. Research findings indicate that the developed contact MASW measurement can fully capture the variation of dispersion characteristics of surface waves induced by debonding defects in SCCS. The developed IR and IT methods are suitable for detecting interfacial debondings in different dimensions. Besides, the damage nephogram resolution of IR is higher than that of the IT method. In addition, the practicability of traditional ultrasonic CT scanning tests, scanning IE method, and UT techniques using commercial equipment is investigated. Experimental observations show that classical NDT testing techniques are incapable of effectively identifying the existence of interfacial damage and are unsuitable for NDT tests on SCCS. The research findings in this study clearly exhibit the precision and limitation of various contact NDT techniques and lay a solid foundation for interfacial debonding detection in practical SCCS.

Actuating Performance Analysis of a New Smart Aggregate Using Piezoceramic Stack

A new type of smart aggregate using piezoceramic stack (SAPS) was developed for improved output, as compared with a conventional smart aggregate with a single piezoceramic patch. Due to the better output, the proposed smart aggregate is preferred where the attenuating effect is strong. In this research, lead zirconate titanate (PZT) material in the form of discs was used due to its strong piezoelectric performance. For analysis, the proposed SAPS was simplified to a one-dimensional axial model to investigate its electromechanical and displacement output characteristics, and an experimental setup was designed to verify the simplified model. Moreover, the influence of the structural parameters, including the number of the PZT discs, the dimensions of the PZT disc, protective shell, and copper lids, and the elastic modulus of the epoxy on the electromechanical and displacement output performance of SAPSs, were numerically studied by using the one-dimensional axial model. The numerical analysis results indicate that the structural dimension of the PZT discs has a greater effect on the electromechanical performance of SAPSs than that of the protective shell and copper lids. Moreover, the results show that the number of the PZT discs and the outer diameter of the protective shell have a much greater influence on the displacement output of SAPSs than other parameters. The analysis results of SAPSs with different elastic moduli of the epoxy demonstrate that the SAPSs’ first resonance frequency, first electromechanical coupling factor, and displacement output change less than 1.79% when the epoxy’s elastic modulus changes from 1.28 GPa to 5.12 GPa, which indicates that the elastic modulus of the epoxy has a limited influence on the property of SAPSs, and it will be helpful for their fabrication. This study provides an approach to increasing the output of SAPS and also develops a method to design the structure of SAPSs.

Parameter Identification of the Nonlinear Piezoelectric Shear d15 Coefficient of a Smart Composite Actuator

The objective of this work is to characterize the nonlinear dependence of the piezoelectric d15 shear coefficient of a composite actuator on the static electric field and include this effect in finite element (FE) simulations. The Levenberg-Marquardt nonlinear least squares optimization algorithm implemented in MATLAB was applied to acquire the piezoelectric shear coefficient parameters. The nonlinear piezoelectric d15 shear constant of the composite actuator integrated with piezoceramic d15 patches was obtained to be 732 pC/N at 198 V. The experimental benchmark was simulated using a three-dimensional piezoelectric FE model by taking piezoelectric nonlinearity into consideration. The results revealed that the piezoelectric shear d15 coefficient increased nonlinearly under static applied electric fields over 0.5 kV/cm. A comparison between the generated transverse deflections of the linear and nonlinear FE models was also performed.

A chip-sized piezoelectric receiver for low-frequency, near-field wireless power transfer: design, modeling and experimental validation

This work presents the design, modeling and characterization of a chip-sized piezoelectric receiver for low-frequency, near-field wireless power transmission. Utilizing a laser micro-machined titanium suspension, one NdFeB magnet, and two PZT-5A piezo-ceramic patches, the receiver operates at its torsion mode mechanical resonance. Two unimorph piezo-ceramic transducers are designed to maximize the power density of the receiver while maintaining a low mechanical resonant frequency for low-frequency electrodynamic wireless power transmission. An equivalent lumped-element circuit model is used to model the system performance. A prototype device is fabricated, assembled and tested, and the experimental results are compared with the system model. The 0.08 cm3 device generates a maximum of 360 μW average power at 1 cm distance from a transmitter coil operating at 724 Hz and below human head and torso exposure limits. This data corresponds to 4.2 mW cm−3 power density. Overall, this volume-efficient design offers a low-profile and compact footprint for potentially wirelessly charging wearable and bio-implantable devices.

Modal effective electromechanical coupling coefficient of shear-mode piezoceramic sandwich cantilevers with segmented multicore: Experimental and numerical assessments

Smart sandwich cantilevers with aluminum faces and single and double cores, formed by assembled shear-mode piezoceramic patches with same poling, are experimentally and numerically assessed for the first time. To measure the electromechanical coupling efficiency of such vibrating smart structures, the so-called modal effective electromechanical coupling coefficient is used as a performance indicator. Hence, it is first experimentally analyzed under different electric connections (short circuit, open circuit, series wiring, and parallel wiring) of the patches’ electrodes; then, it is numerically investigated for models with different refinements (equipotential constraints and bonding adhesives) using ABAQUS® three-dimensional finite element simulations. It is found that the experimental modal effective electromechanical coupling coefficient is low for the smart shear-mode piezoceramic single core sandwich but can be increased using multilayer designs, as confirmed by the smart shear-mode piezoceramic double core sandwich. Numerically, it is found that the electric connection has less influence on the modal effective electromechanical coupling coefficient evaluation than the equipotential constraints and adhesives modeling, in particular for the smart shear double core sandwich. The proposed two benchmarks can be used by the research community of smart structures, systems, and devices for validating new shear-mode response-based theories and numerical models or designing related engineering applications, such as shunted damping, energy harvesting, structural health monitoring, resonators, and filters.

Power Conversion Efficiency of Cantilever-Type Vibration Energy Harvesters Based on Piezoceramic Films

Piezoelectric energy harvesters are very attractive to supply devices for remote sensing applications; however, they suffer from some limitations related to their low-power generation. Recently, piezoceramic flexible patches with high power conversion efficiency have been made commercially available. These film transducers can be suitably used to realize compact low-cost vibration energy harvesters. In this article, the performance of a cantilever-type piezoceramic energy harvester (PCEH) has been thoroughly investigated. Different resonance configurations were obtained by varying the proof mass attached to the free end of the beam. The effects of the excitation features (amplitude and frequency) on generated power and energy conversion efficiency have been evaluated. Furthermore, a rectification and regulation circuit was connected downstream to the PCEH in order to achieve a dc output. In such configuration, the influences of the resonance frequency and the electrical load on the recharging and discharging times were also assessed.

Experimental Investigation of Damage Evolution Characteristics of C50 Concrete under Impact Load

Impact loads widely exist in practical engineering and often cause cumulative damage and cracks or even fracture failure of concrete structures with their repeated long-term action. This experimental research is conducted on the damage evolution characteristics of concrete under impact loads by regarding C50 nonreinforced concrete as the research object and using a self-developed drop-weight device with electromechanical impedance measurement technology. Results show the following. (1) Under low-energy impact, concrete damage has long continuous development process and remarkable cumulative effects. An apparently sudden break characteristic appears before failure. Under high-energy impact, concrete damage accumulates rapidly, and piezoceramic patch signals grow linearly. (2) The root mean square deviation (RMSD) of the concrete increases exponentially with impact times. Particularly, when the RMSD exceeds 0.075, the concrete damage process enters the rapid development stage and approaches the critical failure state. (3) Under the experimental conditions in this study, the relationship between the ultimate impact times (damage life) and impact heights of the concrete samples shows the development trend of the power function. The above results can provide reference for the research on service life prediction methods of concrete structures under impact loads.

PZT-Based Soil Compactness Measuring Sheet Using Electromechanical Impedance

Compaction is a crucial process in road construction and the compactness is an important parameter in determining the road foundation quality. Traditional compaction monitoring methods are based on different principles. The major principle of these techniques is detecting the water content and bulk density of the soil, and then calculating the dry density and the compactness. The disadvantages are laborious, low accuracy, low efficiency and costly for large scale measurement. These drawbacks may limit their application in certain aspects. In this paper, a novel electromechanical impedance (EMI) based compactness measuring sheet (CMS) for soil compactness monitoring was proposed. The proposed CMS was fabricated by attaching a circular piezoceramic patch onto a circular sheet with a larger size. Eight round CMSs with a diameter of 150 mm, 100 mm, 80 mm, 50 mm were fabricated in this experimental study. Among them, four CMSs were embedded into soil and subjected to compression tests to simulate the increased soil compaction. In this study, the conductance signatures of the proposed CMS were collected and analyzed during the increasing soil compaction process. Experimental results demonstrated that all the peak magnitudes in the conductance signatures in the selected frequency range of 160 kHz to 310 kHz were reduced with the increase of soil compaction. It showed that some specific frequencies shifted to the right side during the compaction process. The variations in the conductance signatures were then quantified with the aid of three statistical metrics. These metrics include root mean square deviation (RMSD), mean absolute percentage deviation (MAPD), and correlation coefficient deviation (CCD). Through calculation, all these metrics increase with the increase of soil compaction, which can be employed as indicators in the soil compaction process. To obtain more insight into CMS electromechanical system, the finite element analysis were also performed to study the EMI response. The simulation results well verified the experimental results. This preliminary study has verified that the proposed EMI based CMS is feasible and effective in monitoring soil compactness and shows a promising application prospect.

Experimental validation of piezoelectric shunt tuning with residual mode correction: Damping of plate-like structures

The effective vibration mitigation properties of piezoceramic patches with inductive-resistive shunts are investigated experimentally. A shunt tuning method is proposed, in which a consistent correction for the influence from residual vibration modes is included by an effective modal capacitance, evaluated from measured charge and voltage amplitudes in short- and open-circuit conditions, respectively. The robustness of the proposed method is verified experimentally for both a free beam and a free plate structure with four shunted piezoceramic patch pairs. A stable and fully passive inductor is produced by winding a copper wire around a magnetic core, which requires precise inductance tuning to determine the final number of turns. It is demonstrated that the effective modal capacitance interpolates consistently between the blocked and static capacitances, commonly used for single-mode tuning of piezoelectric inductive-resistive shunts. By imposing pseudo-random vibrations, the piezoelectric current and voltage signals are measured and evaluated by their frequency response functions. Spectrum peak values determine the apparent short-circuit charge to open-circuit voltage ratio for each shunt, which directly determines the shunt components by explicit tuning formulas. Good correlation between numerical and experimental results are obtained for the free beam, while for the free plate experiment effective multi-mode shunt tuning is obtained by a modified effective electromechanical coupling coefficient.

Experimental Characterization of Piezoelectric Transducers for Automotive Composite Structural Health Monitoring

<div class="section abstract"><div class="htmlview paragraph">Composite materials are a natural choice for automotive applications where mechanical performance and lightweight are required. Nevertheless, attention should be directed to the defects into the material. This paper presents the building up of a Structural Health Monitoring system based on a piezoelectric transducers network: a continuous data system acquisition has been carried out in order to detect the presence of faults inside the analyzed structure. A piezoceramic patch has been coupled to a host structure in composite, to characterize the acquisition and the transmission of a wave signal on the material. The importance of this advanced technology research and the positive results obtained in the case study constitute the starting point for future application of piezoelectric-based Structural Health Monitoring systems over real industrial components.</div></div>

Piezoelectric d15 Shear-Mode Sensor in Parallel and Series Configurations

The sensor response experiments of piezoceramic shear same poled d15 patches which are integrated in a composite sandwich beam-like structure and connected in parallel and series configurations are presented in this letter. The core of the smart structure is formed from four piezoceramic shear d15 patches arranged in the same polarization (SP) direction and sandwiched between two identical glass fiber/epoxy layers. The dynamic response of the composite structure was monitored using these four piezoceramic shear d15 patches acting as sensors in parallel and series configurations and the data were evaluated by a pulse-multianalyzer system. A charge amplifier was used as a signal conditioning circuit between the piezoceramic shear d15 patches and the pulse-multianalyzer system. The outputs of the piezoceramic shear sensor were in a short-circuit state with the use of the charge amplifier. The results are promising as the proof of using piezoceramic shear same-poled d15 patches to sense the response of beam-like composite structures.

Multi-mode piezoelectric shunt damping with residual mode correction by evaluation of modal charge and voltage

A resonant, piezoelectric shunt tuning procedure is based on the limiting eigenvalue problems associated with short and open circuiting of the piezoelectric domains attached to a vibrating structure. Whereas short circuit and open circuit frequencies are directly obtained from the eigenvalues, the associated electrical equation further determines a modal charge as an short circuit reaction force and a new modal voltage from the electric deflection in the open circuit limit. By a modal representation with short circuit mode shapes the structural equation fully decomposes, while the inherent contributions from non-resonant vibration modes in the corresponding electrical equation consistently define an effective modal capacitance, conveniently estimated by the modal charge to voltage ratio. The shunt tuning is obtained from the governing characteristic equation for the targeted vibration mode, in which the residual mode correction is explicitly represented by the effective modal capacitance. The tuning procedure with an effective modal capacitance is generalized to multiple piezoelectric domains with independent shunts for simultaneous damping of multiple vibration modes. The accuracy of the proposed shunt tuning methods is demonstrated by a numerical beam example with three piezoceramic patch pairs and independent resistive–inductive shunts. The analysis is carried out in a commercial finite element program, in which the required modal frequencies, charge and voltage are readily available as output to the short circuit and open circuit eigenvalue problems.

Piezoceramic patches for energy harvesting and sensing purposes

This paper deals with a design, modelling, simulation, and test of vibrating mechanical cantilever with bonded piezoelectric patches for energy harvesting and sensing purposes. An experimental flexible structure was designed and piezoceramic patches were placed originally as energy harvesting devices. Furthermore, additional sensing functionality of piezoceramic patches is investigated in this paper. Such piezoceramic patches are integrated in the cantilever design and they could represent, for example, smart layers of an advanced aircraft structure. The design and position of the piezoceramic patches were analysed in the ANSYS environment. The finite element model was used to predict output voltage and power for varied vibration modes. This proposed design of the cantilever with piezoceramic patches was tested in laboratory conditions, and voltage response for varied mechanical excitation was measured and analysed for both energy harvesting and sensing purposes. Proposed paper will also present an example of practical usage of the tested design for impact detection. It could be mainly used in structural monitoring systems or health and usage systems in aircraft applications.

Analytical Modeling and Experimental Validation of an Energy Harvesting System for the Smart Plate with an Integrated Piezo-Harvester.

The literature on piezoelectric energy harvesting (PEH) is strongly focused on structures, like cantilever beams with piezoceramic layers, due to the fact that they are easily modelled and implemented. As compared to the number of studies dealing with the aforementioned case, research on 2D structures with an attached piezoceramic patch harvester is very limited. Thus, an analytical modeling and experimental validations of a piezo harvester structurally integrated on a thin plate with SFSF (Simply supported-Free-Simply supported-Free) boundary conditions is presented in this paper. The distributed parameter electroelastic model of a harvester bonded to an aluminum plate with both piezo-patch actuators is developed on the basis of the Kirchhoff plate theory and the modal analysis for physical and modal coordinates. This allows to estimate the steady-state value output voltage for each odd mode in the frequency range of 10–300 Hz. Finally, the obtained results for the electroelastic analytical model is experimentally verified on a laboratory stand.

General numerical implementation of a new piezoelectric shunt tuning method based on the effective electromechanical coupling coefficient

A recently proposed tuning method for resistive-inductive (RL) shunts is implemented in a commercial finite element (FE) code (ANSYS®). A main result of the paper is therefore the consistent formulation of the tuning method in terms of variables directly available as solutions in any commercial FE code: The two natural frequencies associated with short- and open-circuit (SC and OC) electrodes and a modal charge obtained as the electrical SC reaction force. An alternative method is based on quasi-static solutions with SC and OC electrodes, convenient for both numerical analysis and experiments. The proposed shunt tuning method is suitable for implementation in any commercial FE software supporting electromechanical analysis and ANSYS® has been used to assess its accuracy for a piezoelectric smart plate benchmark problem. The method is finally extended to multiple piezoceramic patches, placed symmetrically on the structure and shunted to a single RL network, whereby more vibration modes can be effectively controlled for the specific plate problem.

Damage Analyses of Replaceable Links in Eccentrically Braced Frame (EBF) Subject to Cyclic Loading

In the current design of steel eccentrically braced frames (EBFs), the yielding link is coupled with the floor beam. This causes the design of cross-sectional dimensions of links to be enlarged, resulting in over-designed structures and foundations, and increasing the cost of the overall structure. In addition, the beams are forecast to sustain severe damage through repeated inelastic deformations under design-level earthquakes, and thus the structure may require extensive repair or need to be replaced. To improve upon these drawbacks, a shear device with replaceable links based on EBFs was designed. The hysteresis curve, the stress distribution, and the deformation of the specimen were obtained by cyclic loading tests of the eight replaceable links. The energy dissipation behavior, the bearing capacity, the failure modes, and the plastic rotation angle of those specimens were analyzed. The results indicated clearly that the links in this shear device had inelastic deformation concentrated in the link showing very stable hysteresis behavior, and damaged links were replaced easily as end-plate connections were adopted. The energy dissipation capacity and the plastic rotation angle of the specimens were mainly dependent on the arrangement of stiffener, length ratio, and welding access holes. Experimental studies performed in this research and the related damage analyses reveal that cracks are the major causes of damage to the EBF and there is a lack of research on real-time monitoring of the onset and development of these cracks in EBF structures. As a future work, this paper proposes a piezoceramic patch transducer-based active sensing approach to monitor the crack onset and development of the EBF when subjected to dynamic loadings.

Optimal piezoelectric resistive–inductive shunt damping of plates with residual mode correction

This work concerns vibration suppression of plates and plate-like structures by resonant piezoelectric damping, introduced by resistive–inductive shunts. The performance of this type of shunt damping relies on the precise calibration of the shunt frequency, where an important aspect is the ability to account for the energy spill-over from the non-resonant modes, not taken into account by most available calibration methods. A newly proposed calibration procedure includes this residual mode contribution by a quasi-dynamic modal correction, taking both flexibility and inertia effects of the non-resonant modes into account. In this work, this procedure is implemented in a finite element model combining Kirchhoff plate bending kinematics for the host structure and a plane stress assumption for a pair of bonded piezoceramic patches. The established model is verified by comparison with shunt calibrations from benchmark examples in the literature. As demonstrated by frequency response plots and the obtained damping ratios, the resistive–inductive shunt tuning is influenced by the effect of the non-resonant modes and omission may yield a significant detuning of the shunt circuit. Finally, an alternative method for precise evaluation of the effective (or generalized) electromechanical coupling coefficient is derived from the modal electromechanical equations of motion. This results in a new shunt tuning method, based on the effective electromechanical coupling coefficient obtained by the short- and open-circuit frequencies of the coupled piezo-plate structure.

Self-heat generation of embedded piezoceramic patches used for fabrication of smart materials

The use of smart materials, with embedded sensors and active actuators to provide real-time monitoring and controlling capabilities, has greatly increased in last decades. Piezoceramic flexible patches (PFPs) are particularly suitable for these applications due to their low thickness and intrusiveness. A critical point, when they are used as embedded actuators, is their self-heating, which can be a concern especially if structural materials with very low thermal conductivity such as plastic reinforced composites are considered. This paper aims to investigate such issue by examining three paradigmatic case studies: a) PFP in a “free” exposed to static air; b) PFP enclosed between two skins of polymeric material and c) PFP embedded into a glass fibre reinforced plastic (GFRP) composite panel. The main goal of the research has been to assess how the temperature, produced by self-heating of the piezo ceramic, is influenced by the surrounding material as the patch is enclosed or embedded into a structural element. A sensitivity analysis was performed to evaluate the effect on self-heating of either the amplitude or the frequency of the driven voltage. Moreover, a simple theoretical model, based on energies balance, has been derived in order to estimate the actual PFP temperature in both the b) and c) configurations.

STRUCTURAL HEALTH MONITORING USING PZT A REVIEW

Due to the involution of damage occurring in the structure it is difficult to monitor structural health. Electromechanical Impedance technique (EMI) is used for the damage detection in the structural member experimental results are obtained by the applying piezoceramic patches surface bonded and embedded PZT (Lead Zirconate Titanate) patchs are used for the detection of structure failure. This papers reviews online strength gain monitoring of early age concrete is detected with the help of EMI sensing technique. By using this methods detection s well as location, severity estimation is also possible. The piezoceramic materials performs the both works sensor as well as actuator. The proposed method of damage detection are quit effective and sensitive to concrete.

Grout compactness monitoring of concrete-filled fiber-reinforced polymer tube using electromechanical impedance

The concrete-filled fiber-reinforced polymer tube (CFFT) is a type of structural element widely used in corrosive environments. Poor grout compactness results in incomplete contact or even no contact between the fiber-reinforced polymer (FRP) tube and the concrete grout, which reduces the load bearing capacity of a CFFT. The monitoring of grout compactness for CFFTs is important. The piezoceramic-based electromechanical impedance (EMI) method has emerged as an efficient and low-cost structural health monitoring technique. This paper presents a feasibility study using the EMI method to monitor grout compactness of CFFTs. In this research, CFFT specimens with different levels of compactness (empty, 1/5, 1/3, 1/2, 2/3, and full compactness) were prepared and subjected to EMI measurement by using four piezoceramic patches that were bonded circumferentially along the outer surface of the CFFT. To analyze the correlation between grout compactness and EMI signatures, a compactness index (CI) was proposed based on the root-mean-square deviation (RMSD). The experimental results show that the changes in admittance signatures are able to determine the grout compactness qualitatively. The proposed CI is able to effectively identify the compactness of the CFFT, and provides location information of the incomplete concrete infill.