PZT Interface Research Articles

Impedance-based Identification of Strand Looseness in Multi-strand Anchorage under Temperature Effects

In this study, strand looseness in a multi-strand anchorage is identified using measured impedance features of the PZT (Lead zirconate titanate) interface array under temperature effects. Firstly, a PZT-interface method for impedance monitoring in prestressed structures is briefly described. Secondly, a finite element model of multi-strand anchorage equipped with a PZT array is established to analyze the effects of prestress loss and temperature changes in impedance features. Thirdly, variations in simulated impedance signals are quantified using statistical damage metrics for damage detection in the analyzed structure. Last, a test on real-scale multi-strand anchorage is conducted to measure impedance signatures of the PZT interface under temperature fluctuation and prestress loss. The measured signals are then quantified using damage metrics for prestress looseness monitoring. The result reveals that environmental changes cause significant changes in PZT interfaces’ impedance features and affect strand looseness monitoring results.

Identification of Simulated Damage in Prestressed Anchorage Using Admittance-Based Active Sensing Technique

This study examined the feasibility of the admittance-based method for detecting simulated damage in the bearing plate of a prestressed anchorage. The proposed method utilized the PZT (lead zirconate titanate) interface technique to acquire a strong admittance response from the anchorage. Firstly, the numerical feasibility of the method was demonstrated by detecting the presence of fatigue cracks and preload changes in a fixed–fixed beam-like structure. Next, the experimental verification was carried out using a lab-scale prestressed anchorage model. A PZT interface prototype was designed and surface-mounted on the bearing plate. The admittance response of the PZT interface was measured before and after the simulated damage cases of the bearing plate. Afterwards, a statistical damage metric, root-mean-square deviation (RMSD) was used to quantify the change in the admittance spectrum and identify the damage’s presence. It was shown that the experimental admittance response was consistent with the numerical simulation result in the same effective frequency band. Both the numerical and experimental results showed clear shifts in the admittance spectrum due to structural damage. The simulated damages in the bearing plate were successfully identified by the RMSD evaluation metric.

Raspberry Pi Platform Wireless Sensor Node for Low-Frequency Impedance Responses of PZT Interface.

A wireless impedance monitoring system, called SSeL-Pi, is designed to have cheap, mobile, and handy practical features as compared to wired commercial impedance analyzers. A Raspberry Pi platform impedance sensor node is designed to measure signals at a low-frequency range of up to 100 kHz. The low-frequency impedance measurement via the proposed node has been combined with a new PZT interface technique for measuring local responses sensitive to structural damage. The new PZT interface can work as a surface-mounted or embedded sensor, and its local dynamic characteristics are numerically analyzed to pre-determine an effective impedance resonant frequency range of less than 100 kHz. Next, a software scheme was designed to visualize the input/output parameters of the proposed SSeL-Pi system (i.e., Raspberry Pi platform and PZT interface) and automate signal acquisition procedures of the impedance sensor node. The calibration for impedance signals obtained from the proposed system was performed by a series of procedures, from acquiring real and imaginary impedance to adjusting them with respect to a commercial impedance analyzer (HIOKI-3532). The feasibility of the wireless impedance monitoring system was experimentally evaluated for PZT interfaces that were subjected to various compressive loadings. The consistent results analyzed from signals measured by the SSeL-Pi and HIOKI 3532 systems were observed. Additionally, the strong relationships between impedance features (frequency shift and RMSD index) and compressive stresses of the PZT interfaces showed the potential for axial force/stress variation monitoring in real structures using the Raspberry Pi platform impedance sensor node and developed PZT interface.

Three-dimensional finite element simulation of magnetic-mechanical-electrical coupling in layered cylindrical multiferroic structures

The excellent magnetoelectric (ME) performance of multiferroic structures under room temperature has inspired a wide range of applications in smart devices like energy collectors, ME transducers, neo-antennas, etc. Starting from the constitutive equations of ferroelectric and ferromagnetic materials, a three-dimensional (3D) finite element simulation model was set up to investigate the ME behaviors of the cylindrical structures consisting of Terfenol-D and lead zirconate titanate (PZT). Then the solid mechanical module, electrostatic module and the magnetic module are coupled to calculate the mechanical, electrical and magnetic properties of the components and the structures. The calculated ME coefficients were in good agreement with the experimental data. The results show that P/T and T/P structures reach the maximum of ME coefficients at different bias magnetic fields, approximately 2.5×104 A/m for P/T structure and 4.8×104 A/m for T/P structure. The maximum value of αE31 in the P/T structure is twice that of T/P structure. Moreover, the distribution of magnetic, mechanical, and electrical fields of the composites are also analyzed. The results show that the magnetization of the ferromagnetic material exhibits a non-uniform distribution at low magnetic field, the stress concentration occurs at the Terfenol-D and PZT interface, and the electric potential of piezoelectric material is non-uniform in the plane. Finally, the influence of the interface characteristics on the ME effect is also studied. It is found that, the thicker the interface and the lower the Young's modulus, then the smaller the corresponding ME coefficient for the P/T structure.

Numerical Simulation of Single-Point Mount PZT-Interface for Admittance-Based Anchor Force Monitoring

This study investigates the dynamic characteristics of a smart PZT interface mounted on a prestressed anchorage to verify the numerical feasibility of the admittance-based anchor force monitoring technique. Firstly, the admittance-based anchor force monitoring technique through a single-mount PZT interface is outlined. The admittance response of the PZT interface-anchorage system is theoretically derived to show the proof-of-concept of the technique for anchor force monitoring. Secondly, a finite element model corresponding to a well-established experimental model in the literature is constructed. The effect of anchor force is equivalently treated by the contact stiffness and damping parameters at the bottom surface of the anchorage. Thirdly, the admittance and the impedance responses are numerically analyzed and compared with the experimental data to evaluate the accuracy of the numerical modelling technique. Fourthly, the local dynamics of the PZT interface are analyzed by modal analysis to determine vibration modes that are sensitive to the change in the contact stiffness (i.e., representing the anchor force). Finally, the admittance responses corresponding to the sensitive vibration modes are numerically analyzed under the change in the contact stiffness. The frequency shift and the admittance change are quantified by statistical damage indices to verify the numerical feasibility of the anchor force monitoring technique via the smart PZT interface. The study is expected to provide a reference numerical model for the design of the single-point mount PZT interface.

Anchor Force Monitoring Using Impedance Technique with Single-Point Mount Lead-Zirconate-Titanate Interface: A Feasibility Study

As a key load-bearing element in a prestressed structure, the anchor should be appropriately monitored to secure its as-built prestressing force. In previous studies, the impedance-based prestress force monitoring technique through a mountable lead–Zirconate–Titanate (PZT) interface was developed. However, the previous design of the PZT interface uses a two-point mount technique through two bonding layers, causing inconveniences during installation and replacement processes. To address this issue, we propose an alternative PZT interface model for prestress force monitoring based on the impedance method. The proposed model uses a single-point mounting technique that allows it to be more conveniently installed and replaced on a host structure. First, the electromechanical impedance of the proposed PZT interface is theoretically derived. The proof-of-concept of the proposed PZT interface for impedance monitoring is then shown by finite element modelling. Afterwards, a lab-scaled experiment is conducted on an anchoring system to demonstrate the practical application feasibility of the proposed technique. The obtained results show that the proposed technique can produce impedance responses that are highly sensitive to the prestress force. The performance of the proposed model for impedance-based prestress force monitoring is found to be comparable with the previous techniques (the washer-type mount and the two-point mount). Due to its advantage of simple design, the newly designed PZT interface is promising for the future development of the impedance-based anchor force monitoring systems in practice.

Piezoelectric‐based hoop‐type interface for impedance monitoring of local strand breakage in prestressed multi‐strand anchorage

In this study, a piezoelectric-based interface technique for impedance measurement is presented to monitor local strand breakage in multi-strand anchorage systems. Firstly, a hoop interface-based impedance measurement model is designed based on stress behaviors of the multi-strand anchorage. Coupled dynamic behaviors between the lead zirconate titanate (PZT) interface and the target tendon anchorage are interpreted to determine sensitive frequency ranges under local strand breakage. Next, a prototype of the PZT interface is designed to fit into the target multi-strand anchorage to monitor the stress variations induced by local strand breakages. Dynamic characteristics of the PZT interface are numerically analyzed to sensitively catch impedance signals in predetermined frequency ranges. Finally, a series of damage scenarios are tested on a full-scale multi-strand anchorage system to evaluate the feasibility of the PZT interface for monitoring a series of strand-breakage cases. Impedance responses of the PZT interface prototype are analyzed to determine damage-sensitive frequency ranges. Linear tomography of root-mean-square-deviation (RMSD) indices is utilized to localize damaged strands.

Sensitivity of Piezoelectric-Based Smart Interfaces to Structural Damage in Bolted Connections.

This study presents a set of experimental and numerical investigations to study the sensitivity of the piezoelectric-based smart interface device to structural damage in a bolted connection. The study aims to identify the proper geometric sizes of smart interfaces for damage detection tasks. First, the fundamentals of the damage monitoring technique via lead zirconate titanate (PZT) interface is briefly described for a bolted connection. Second, a lab-scaled girder connection is selected as the test structure for the experimental investigation. PZT interface prototypes with varying geometric sizes are designed for the test connection. Under the bolt-loosening inflicted in the connection, the impedance responses of the PZT interfaces are analyzed to understand the effect of geometric parameters on the damage sensitivity of the impedance responses. Subsequently, the bolt-loosening detection capabilities of the PZT interfaces are comparatively evaluated for identifying the proper geometric sizes of the devices. Finally, a finite element model of the PZT interface-bolted connection system is established for the numerical investigation. The damage sensitivity of the numerical impedance responses is compared with the experimental results for the verification.

Sensing Region Characteristics of Smart Piezoelectric Interface for Damage Monitoring in Plate-Like Structures

For impedance-based damage detection practices, the sensing range of piezoelectric devices is an important parameter that should be determined before real implementations. This study presents numerical and experimental analyses for characterizing the sensing region of a smart PZT (lead–zirconate–titanate) interface for damage monitoring in plate-like structures. First, a finite element (FE) model of the PZT interface mounted on a plate structure is established. The impedance responses of the PZT interface are numerically simulated under different damage locations inflicted in the plate domain. The impedance features are extracted from the impedance signatures to analyze the sensing distance and the damage detectability of the PZT interface. Next, the splice plate of a bolted connection is selected as a practical plate-like structure for the experimental examination of the PZT interface’s sensing region on a limited plate domain. The damage sensitivity behavior of the PZT interface is analyzed with respect to the damage location on the splice plate. An FE analysis of the corresponding PZT interface-splice plate system is also conducted to support the experimental results.

Local Strand-Breakage Detection in Multi-Strand Anchorage System Using an Impedance-Based Stress Monitoring Method-Feasibility Study.

This study investigates the feasibility of impedance-based stress monitoring method for local-strand breakage detection in multi-strand anchorage systems. Firstly, stress fields of a multi-strand anchorage system are numerically analyzed to examine anchorage’s responses sensitive to local strand breakage. Secondly, an impedance-based stress monitoring technique via the PZT interface is outlined. Thirdly, a novel hoop-type PZT interface is designed for the multi-strands anchorage to monitor the stress variation induced by the strand breakage. Local dynamic responses of the hoop-type PZT interface are analyzed to predetermine the effective frequency ranges. Finally, the numerical feasibility of the proposed method is verified on a seven-strand anchorage system under various strand breakage cases. Variations in impedance responses are statistically quantified, and broken strands are localized by linear tomography analysis of damage indices. A lab-scale experiment is also conducted on a multi-strands anchorage to evaluate the realistic performance of the hoop PZT interface for impedance-based stress monitoring method.

Tunable Piezophotonic Effect on Core-Shell Nanoparticles Prepared by Laser Ablation in Liquids under External Voltage

We report an experimental study on the piezophotonic effect of gold and lead zirconate titanate (PbZrTiO3) nanoparticles (NPs) and also their core-shell nanostructures prepared by the laser ablation in liquid method. To obtain these NPs and composite materials, the targets were immersed in deionized water and a polymeric solution of polyvinyl pyrrolidone (PVP) under Nd:YAG laser pulses irradiation. Linear and nonlinear properties of these NPs were studied by optical spectroscopy and the Z-scan technique. Furthermore, tunable nonlinear properties of the NPs were measured under an external electric field under illumination to investigate the piezophotonic effect. Our results show that, at the interface of PZT and Au, due to the Schottky barrier, we have electron/hole recombination prevention, which leads to efficient enhancement in the nonlinear properties.

Quantification of temperature effect on impedance monitoring via PZT interface for prestressed tendon anchorage

In this study, the quantification of temperature effect on impedance monitoring via a PZT interface for prestressed tendon-anchorage is presented. Firstly, a PZT interface-based impedance monitoring technique is selected to monitor impedance signatures by predetermining sensitive frequency bands. An analytical model is designed to represent coupled dynamic responses of the PZT interface-tendon anchorage system. Secondly, experiments on a lab-scaled tendon anchorage are described. Impedance signatures are measured via the PZT interface for a series of temperature and prestress-force changes. Thirdly, temperature effects on measured impedance responses of the tendon anchorage are estimated by quantifying relative changes in impedance features (such as RMSD and CCD indices) induced by temperature variation and prestress-force change. Finally, finite element analyses are conducted to investigate the mechanism of temperature variation and prestress-loss effects on the impedance responses of prestressed tendon anchorage. Temperature effects on impedance monitoring are filtered by effective frequency shift-based algorithm for distinguishing prestress-loss effects on impedance signatures.

Quantitative damage identification in tendon anchorage via PZT interface-based impedance monitoring technique

In this study, the severity of damage in tendon anchorage caused by the loss of tendon forces is quantitatively identified by using the PZT interface-based impedance monitoring technique. Firstly, a 2-DOF impedance model is newly designed to represent coupled dynamic responses of PZT interface-host structure. Secondly, the 2-DOF impedance model is adopted for the tendon anchorage system. A prototype of PZT interface is designed for the impedance monitoring. Then impedance signatures are experimentally measured from a laboratory-scale tendon anchorage structure with various tendon forces. Finally, damage severities of the tendon anchorage induced by the variation of tendon forces are quantitatively identified from the phase-by-phase model updating process, from which the change in impedance signatures is correlated to the change in structural properties.

Compensation of temperature effect on impedance responses of PZT interface for prestress-loss monitoring in PSC girders

In this study, a method to compensate the effect of temperature variation on impedance responses which are used for prestress-loss monitoring in prestressed concrete (PSC) girders is presented. Firstly, an impedance-based technique using a mountable lead-zirconate-titanate (PZT) interface is presented for prestress-loss monitoring in the local tendon-anchorage member. Secondly, a cross-correlation-based algorithm to compensate the effect of temperature variation in the impedance signatures is outlined. Thirdly, lab-scale experiments are performed on a PSC girder instrumented with a mountable PZT interface at the tendon-anchorage. A series of temperature variation and prestress-loss events are simulated for the lab-scale PSC girder. Finally, the feasibility of the proposed method is experimentally verified for prestress-loss monitoring in the PSC girder under temperature-varying conditions and prestress-loss events.

Temperature-dependent electrical transport properties in graphene/Pb(Zr0.4Ti0.6)O3 field effect transistors

We report the temperature and gate voltage dependent electrical properties of PZT gated graphene field effect transistors (PZT-GFETs) in the vacuum atmosphere. The PZT-GFETs exhibit p-type characteristics which are attributed to the chemical doping induced the Fermi level shifting below the Dirac point. Meanwhile, it also shows a large memory window. The temperature dependencies of the source-drain current in the range of 20–300K indicate thermally activated hysteresis behaviors. The hysteresis in the transfer characteristics of PZT-GFETs shows a simultaneous enlargement with increasing temperature. The hysteresis appears to stem from the screening of charges that are transferred from graphene to traps at the interface of PZT and graphene. The magnitude of the charge neutrality point under opposite gate voltage sweep are enhanced with the increase of temperature and gate voltage can be ascribed to the common effects of the temperature and voltage magnitude dependent mechanisms such as interface charge trapping process and the polarization effects of PZT films.

Optimization of La0.7Sr0.3MnO3 thin film by pulsed laser deposition for spin injection

We have investigated low temperature magnetic properties of La0.7Sr0.3MnO3 (LSMO) thin films on SrTiO3 (STO) substrate deposited by pulsed laser deposition (PLD). We observed a large change in the Curie temperature TC when the LSMO film thickness is reduced from 4nm (TC~280K) to 2nm (TC ~100K), which is a result of high strain present at the STO–LSMO interface. The presence of the strain is confirmed by a grazing angle X-ray diffraction (XRD) technique where a particular peak is shifted away from the bulk peak position as we decrease the thickness. In a LSMO/Pb[ZryTi1−y]O3 (PZT)/LSMO magnetic tunnel junction (MTJ), these LSMO thin films can be used for spin injection into the tunnel barrier. Here spin current can be manipulated by changing the strain present at the LSMO–PZT interface by using piezoelectric properties of PZT.

Impedance-Based Cable Force Monitoring in Tendon-Anchorage Using Portable PZT-Interface Technique

In this paper, a portable PZT interface for tension force monitoring in the cable-anchorage subsystem is developed. Firstly, the theoretical background of the impedance-based method is presented. A few damage evaluation approaches are outlined to quantify the variation of impedance signatures. Secondly, a portable PZT interface is designed to monitor impedance signatures from the cable-anchorage subsystem. One degree-of-freedom analytical model of the PZT interface is established to explain how to represent the loss of cable force from the change in the electromechanical impedance of the PZT interface as well as reducing the sensitive frequency band by implementing the interface device. Finally, the applicability of the proposed PZT-interface technique is experimentally evaluated for cable force-loss monitoring in a lab-scaled test structure.

Ruddlesden-Popper Phase Formation in Pb(Zr,Ti)O3 Thin Films

In this work, we give evidences of Ruddlesden-Popper (RP) phase formation in Pb(Zr,Ti)O 3 thin films deposited by multi-target reactive sputtering at a substrate temperature of 520°C onto oxidized silicon wafers comprising a ZrO 2 buffer layer. X-ray diffraction data of films deposited at 520°C revealed the appearance of a Pb 2 (Zr,Ti)O 4 RP phase. High-resolution transmission electron microscopy (HRTEM) images have proved the presence of a corresponding superstructure with a period of about 1.3 nm. It was nucleated on top of an amorphous, lead-enriched interface layer near the ZrO 2 /PZT interface. At higher substrate temperatures, when this amorphous interface layer disappears, a perovskite structure with a sharp interface was nucleated directly on the ZrO 2 buffer layer.

Texture control of Pb(Zr, Ti)O 3 thin films with different post-annealing processes

The non-crystalline Pb(Zr, Ti)O 3 thin films sputtered on Pt(1 1 1)/Ti/SiO 2/Si(1 0 0) substrates at room temperature were crystallized by conventional furnace annealing (CFA) and rapid thermal annealing (RTA), respectively. It was found that the RTA process favored the (1 1 1)-preferred orientation in lead zirconate titanate (PZT) thin films while the CFA process favored the (1 0 0)-preferred orientation. The origin of the different orientation selection might be due to the different epitaxial nucleation mechanism. The long heating duration would lead to the aggregation of Pb and the formation of PbO(1 0 0) on film surface; therefore, the nucleation at the PbO(1 0 0)/PZT interface on film surface might lead to the (1 0 0)-preferred orientation. However, the nucleation at the PZT/Pt(1 1 1) electrode interface by RTA process would result in the formation of (1 1 1)-preferred orientation. The RTA-derived (1 1 1)-preferentially oriented PZT thin films exhibited a high remnant polarization of 35 μC/cm 2.

Ferrite∕piezoelectric microwave phase shifter: studies on electric field tunability

A 1–10 GHz magnetostatic wave (MSW) phase shifter that uses a single crystal yttrium iron garnet (YIG) and lead zirconium titanate (PZT) layered structure as a medium for MSW propagation is studied. The structure provides electric field control of the phase shift due to magnetoelectric interaction at the YIG–PZT interface. Phase shifts of the order of a radian have been obtained for nominal electric fields.