PZT Sensors Research Articles

Performance evaluation concept for crack healing in bacterial concrete structure using electro mechanical impedance technique with PZT patch

Beginning and development of cracks reduce the structural performance and durability, thus a novel strategy is required to prevent such kind of occurrence. The incorporation of bacteria in the concrete system is likewise a technique to prevent the growth of the cracks by the microbial induced calcite precipitation. The Electro mechanical impedance (EMI) technique is the smart sensor-based technology that is an efficacious technique to examine the health of structures, whereas the prediction of frequency band and corresponding healing damage indicator for real-life application is the governing factor. The examination of crack healing performance in bacterial concrete by EMI technique with PZT sensors was not reported by previous studies to date. This research is motivated by the quality evaluation of crack healing in bacterial reinforced concrete beam specimens using the EMI technique with surface-bonded PZT patch and embedded concrete vibration sensor (CVS), respectively. For the fabrication of bacterial reinforced concrete beam specimen, the Gram-positive Bacillus subtilis bacteria have been used. To induce the structural damage, the three point loading was applied to the prepared reinforced concrete beam specimen. The optimal frequency band was determined which resulted in the structural condition for that the four statistical indices were investigated with various crack severities in several sub-frequency bands. The optimal frequency band was determined as 161–215 kHz. Further, the crack healing performance was investigated with a pre-evaluated optimal frequency band using the statistical damage indices. The damage indicators RMSD, MAPD, and CC were appropriate for the evaluation of damage severity; however Cov was appropriate for damage severity evaluation in lesser amounts in a sub-frequency band. The evaluated damage indicators RMSD, MAPD, Cov, and CC successfully signified the crack healing by the bacterial incorporation in concrete structures. The SEM and XRD tests were performed for the confirmation of calcite deposition at the cracks. The developed concept is resulted in significantly evaluating the healing quality of the cracks by bacterial incorporation over time.

Rapid positioning test method for cylindrical structure penetration based on machine learning

Focusing on the requirements of rapid damage location test for multi-layer steel plates penetration of cylindrical structure in the complex and harsh environment, this paper studies the propagation characteristics of high-speed impact stress waves in steel plates. Also, the measurement effects of impact stress in the near zone of penetration hole are compared with different sensors, so as to select appropriate PZT sensors to measure the velocity of impact stress wave in the actual steel plates. Then the array layout scheme is designed, and the corresponding damage location algorithm is determined. Finally, the deep learning algorithm is used to improve the accuracy and efficiency of damage location.

Flexible Mica-Based PZT Sensor for Real-Time Monitoring of the Airflow

Pipeline leakage causes enormous safety and economic concerns; therefore, sensors which are high-performance and durable are in high demand for improving monitoring accuracy and for avoiding economic loss. In this work, mica-based flexible PZT sensors showed high sensitivity, with 140 mV N−1 and 467 mV N−1 for the output voltage, with regard to the tapping and bending modes, respectively. They can monitor airflow in normal conditions with high sensitivity and a linearity of 424 mV MPa−1 and 0.99, respectively. In the event of a pipeline leak, the mica-based sensors exhibited a rapid response time as short as 0.578 s. Furthermore, they generated distinct voltage levels at different distances from the leakage point, thus providing valuable information for accurately locating the source of the leakage.

A PCA-Based Approach for Very Early-Age Hydration Monitoring of Self-Compacting Concrete Using Embedded PZT Sensors.

This work proposed a novel approach based on principal component analyses (PCAs) to monitor the very early-age hydration of self-compacting concrete (SCC) with varying replacement ratios of fly ash (FA) to cement at 0%, 15%, 30%, 45%, and 60%, respectively. Based on the conductance signatures obtained from electromechanical impedance (EMI) tests, the effect of the FA content on the very early-age hydration of SCCs was indicated by the predominant resonance shifts, the statistical metrics, and the contribution ratios of principal components, quantitatively. Among the three, the PCA-based approach not only provided robust indices to predict the setting times with physical implications but also captured the liquid-solid transition elongation (1.5 h) during the hydration of SCC specimens with increasing FA replacement ratios from 0% to 45%. The results demonstrated that the PCA-based approach was more accurate and robust for quantitative hydration monitoring than the conventional penetration resistance test and the other two counterpart indices based on EMI tests.

Detection and Quantification of Asymmetrically Located Structural Damages by Mode Converted Guided Waves Using Piezo Electric Elements

Though damage identification using guided waves generated using ultrasonics is well proven, its usage for structural health monitoring poses difficulties. Piezo electric actuation and sensing overcomes this difficulty to some extent. In this work, usage of such guided waves for damage identification is investigated. Piezo electric wafer transducers are used for generating and sensing the guided waves. Presence of multiple modes and comparatively higher speeds of the guided waves throw up difficulties in damage identification. It is shown here that this problem can be addressed by considering different sensor location with respect to the damage with suitable interpretation of the results. Usage of fundamental antisymmetric (Ao) mode is found to be more suitable in localizing the damage compared to the fundamental symmetric (So) mode. Asymmetrically located damage causes mode conversion. It is demonstrated in this work that the mode converted guided wave (So) could be advantageously used for identification, localization, and quantification of the damage. Damage identification and localization schemes are evolved based on the location of the sensors with respect to the damage. It is shown that the reduction in the magnitude of the mode converted wave can be utilized for assessing the depth of the damage. 3D finite element based numerical models incorporating a PZT sensor are developed and validated with experimental results in terms of the characteristics of the waves, mode conversion due to damage and influence of the defect size on the received signals which are necessary for quantification of the damage.

Invention of smart tightening tool for directly controlling the preload of bolted joints

Bolted joints are widely used in industries to connect and fasten two separated components. During the assembly of bolted joints, torque wrench is commonly employed to control preload indirectly. Much scatter in preload will occur and decrease the reliability of mechanical product. This study invented a novel tightening tool, which could directly control preload with high accuracy in the process of tightening bolts. The novel tightening tool is composed of an ameliorative intelligent wrench and signal processing system. There are two characteristics or innovations in the intelligent wrench. First, an electric tripping structure with multi-level small-size lever is designed to ensure that the target preload can be controlled effectively when the threshold value is reached. Second, an intelligent socket integrated with PZT sensor is designed, which can avoid many PZT sensors being sticked on bolt heads and greatly reduce cost. In the signal processing system, the waveform tracking strategy based on phase-locked loop is proposed to obtain the stable phase difference, which improves the robustness of the calculation of echo time. Three types of bolts with different sizes were tested. The average preload error was approximatively 2%, validating the accuracy and effectiveness of our tightening tool.

Enhancing the control of boron epoxy cross-ply laminated composite plates through intelligent implementation of PZT sensor and actuator

Piezoelectric materials find diverse applications in structural engineering, particularly in fields like condition monitoring, smart control, and testing. The captivating interplay between their mechanical and electrical properties has garnered significant attention, showcasing immense potential for practical utility. Notably, these materials boast costeffectiveness, lightweight characteristics, compact size, exceptional dynamic capabilities, swift responsiveness, enduring stability, and remarkable energy conversion efficiency. In our research initiative, we delve into a study concentrated on the symmetric surface attachment of two piezoelectric patches or actuators onto composite laminate plates. The goal is to induce a bending effect in the laminate by applying equal-magnitude electric voltages with opposite polarities to these symmetrically positioned piezoelectric actuators. The determination of the bending moment involves the application of principles related to elasticity and piezoelectricity. To scrutinize the displacement and natural frequency of the composite plate influenced by this bending moment, we utilize plate theory and derive analytical solutions. Furthermore, these piezoelectric patches, affixed to the composite laminate plate's surface, double as vibration actuators. We subject the plate to loads to investigate its vibration response in a simply supported rectangular configuration. This excitation is achieved by applying time-harmonic voltages to the piezoelectric patches. Throughout our study, we compute analytical solutions for both deflection and vibration amplitude, presenting numerical results that depict the static deflection and vibration amplitude of the plate. Additionally, a parametric study is conducted to elucidate the influence of piezoelectric actuator size and placement on cross-ply composite laminate plates.

A Method of Damage Detection Efficiency Enhancement of PZT Sensor Networks under Influence of Environmental and Operational Conditions

Two performance parameters are particularly important for the assessment of structural health monitoring (SHM) systems, i.e., their damage detection capabilities and risk of false positive indications due to varying environmental and operational conditions (EOCs). A reduced ratio of false-positive indications can be of significant importance for particular applications, for example, in aerospace, where the costs of unplanned maintenance procedures can be very high. In such cases, the reduction of the false calls ratio can be critical for the possibility of the practical application of the system, apart from damage detection efficiency and system costs. Among various sensor technologies, PZT networks are proven to be one of the most universal approaches to SHM, and they were successfully applied in different scenarios. Moreover, many EOCs which may have an impact on the risk of false positive indications have been identified. Over the years, different approaches to the influence of EOCs compensation have been proposed. Compensation methods can be tailored to the particular way in which a given measurement condition, for example, ambient temperature, alters signals acquired by the PZT network or can be formulated to be also applied in the more general case. In the paper, a method for enhancement of damage detection efficiency under influence of EOCs of general nature is proposed. The particular measurement condition affecting signals acquired by PZT sensors neither needs to be measured, which could be hard in some cases, but also nor even have to be identified. The efficiency of the proposed compensation algorithms is verified based on the example of experimental results obtained under varying temperatures.

Monitoring of biochemical based sustainable bacterial concrete system using electromechanical impedance technique with PZT sensor

Monitoring of biochemical based sustainable bacterial concrete system using electromechanical impedance technique with PZT sensor

Elastic Wave Application for Damage Detection in Concrete Slab with GFRP Reinforcement

The aim of the presented examination is condition-monitoring of GFRP-reinforced concrete structural members using elastic wave propagation. As an example, a deck slab is selected. The deck slab is made of concrete of the targeted C30/37 class under three-point bending. During loading cycles, the specimen is observed with a digital image correlation (DIC) system, which enables calculation of the strain field. The measuring setup consists of two Baumer 12.3 Mpx cameras with VS-1220HV lenses, combined in a Q400 system by Dantec Dynamics GmbH. Elastic waves are also measured based on signals recorded with PZT (lead-zirconate-titanate) sensors. Additionally, the typical crack-opening measurements are made. The appearance of a crack and its growth causes changes in both the shape and amplitude of the registered signals. However, the changes are not obvious and depend on the location of the sensors. Due to the impossibility of determining simple parameters with respect to disturbingly wide cracks, for damage detection, an artificial neural network (ANN) is applied. Perfect determination of the specimen's condition (100% properly classified patterns) is possible based on whether the element is under loading or not.

Multiple Damage Detection in PZT Sensor Using Dual Point Contact Method

Lead Zirconate Titanate (PZT) is used to make ultrasound transducers, sensors, and actuators due to its large piezoelectric coefficient. Several micro-defects develop in the PZT sensor due to delamination, corrosion, huge temperature fluctuation, etc., causing a decline in its performance. It is thus necessary to identify, locate, and quantify the defects. Non-Destructive Structural Health Monitoring (SHM) is the most optimal and economical evaluation method. Traditional ultrasound SHM techniques have a huge impedance mismatch between air and solid material, and most of the popular signal processing methods define time series signals in only one domain, which provides sub-optimal results for non-stationary signals. Thus, to improve the accuracy of detection, the point contact excitation and detection method is implemented to determine the interaction of ultrasonic waves with micro-scale defects in the PZT. The signal generated from this method being non-stationary in nature, it requires signal processing with changeable resolutions at different times and frequencies. The Haar Discrete Wavelet Transformation (DWT) is applied to the time series data obtained from the coulomb coupling setup. Using the above process, defects up to 100 μm in diameter could be successfully distinguished.

Three-dimensional scaled boundary finite element method to simulate Lamb wave health monitoring of homogeneous structures: Experiment and modelling

Exploiting scattering and reflection related data of ultrasonic Lamb wave interactions with damage is a common approach to health monitoring of thin-walled structures. Using thin PZT sensors, the method can be implemented in real-time. Simulation of Lamb wave propagation and its interaction with damage plays an important role in damage diagnosis and prognosis. It is, however, a time-consuming task due to the high-frequency waves that are commonly used to detect tiny damage. The current study employs the Scaled Boundary Finite Element Method (SBFEM) for effective modeling of Lamb wave health monitoring of homogenous thin plates. The electromechanical effects of piezoelectric sensors are included in the model to improve accuracy and make the results comparable to those of laboratory experiments. Simple meshing of complex topologies is possible by converting standard finite elements to scaled boundary elements. The 3D SBFEM wave motion equations are solved in the time domain to capture the sensor's PZT response to a high-frequency tone-burst actuation. The results are validated by pitch-catch and pulse-echo laboratory tests carried out on thin plates. SBFEM is used to study wave propagation in complex configurations, such as a stiffened plate, and the results are compared to their FEM counterparts. According to the findings, SBFEM significantly reduces the computational costs associated with simulation of Lamb wave health monitoring while also providing significant accuracy in comparison to the experimental results.

Prediction of remaining life of RCC sewer manhole using smart material-based EMI technique for sustainable environment.

Manholes are vital component of the sewerage system; they are often damaged due to concrete corrosion, hydrogen sulphide (H2S) gas released by sewage effluent and vehicular loading. Due to large number of accidents occurred on the road, there is need for supervision of manholes so that it can be replaced when it is about to damage. In this paper, three different manholes were tested according to Indian standard code IS 12592 (2002). At the same time, using electro mechanical impedance (EMI) technique, the damage quantification was done using root mean square deviation (RMSD) for the obtained signature of the manholes with different damage stages. Three PZT sensors were bonded using epoxy, one each on top and bottom of manhole cover and third at the frame of the manhole. It was found that the PZT bonded at bottom captures the damages well than the PZT bonded on the top of cover, but it shows large variation when the crack line passes through the PZT bonded place, the PZT bonded on the frame shows abrupt variations with the damage. Hence, PZT sensor pasted on top of manhole cover was found to be well correlated to the damage stages. The effective structural parameters were extracted using PZT sensor; moreover, for all the three manhole structures, the structural damping was identified for different damage states. A model was developed including all three manholes with more than 95% confidence level for estimating the remaining life of manhole.

Phased array guided wave propagation in curved plates

For the monitoring of plate structures, phased array guided wave has great application prospects to effectively determine damage location and size. Locating damage via phased array focusing is a challenging task, especially in curved plates. Hence, a systematic understanding of the behavior of the phased array guided wave propagation in curved plates is needed. In this study, a phased array focusing method was proposed for the damage localization of curved plates. Different damage scenarios and phased array focusing schemes are investigated in the finite element plate models with different radii. A high-speed signal generation and acquisition system including PZT actuators and sensors is set up. Experimental tests are carried out on a curved aluminum plate with embedded piezoelectric elements to verify the finite element models. Parametric studies are then performed to evaluate the effect of different radii and damage scenarios on the behavior of phased array guided wave propagation in curved plates. Numerical simulations and experimental results show that the proposed PA method has the capabilities of wave focusing and damage identification in curved plates. The damage localization method using phased array guided wave has the potential to be applied to the real-time monitoring of structures with curved plates.

Determining the Sensing Region of Surface Bonded PZT Sensor and Surface Mounted PZT Sensor in Electro-Mechanical Impedance Technique for Non-Destructive Testing

Determining the Sensing Region of Surface Bonded PZT Sensor and Surface Mounted PZT Sensor in Electro-Mechanical Impedance Technique for Non-Destructive Testing

Interface debonding detection of grouted connection based on Lamb wave energy leakage

Grouted connections (GCs) are transitional elements that have been extensively employed in offshore wind turbine support structure to transfer loads from superstructure to foundation. However, interface debonding defects between steel tube and grout layer have an adverse effect on the durability and fatigue resistance of the GC. An effective interface debonding defects detection approach for GC is necessary. In this study, interface debonding defects detection approach based on Lamb wave energy leakage was proposed and validated numerically and experimentally. Numerical studies on Lamb wave energy leakage models and the GC models were performed to study mechanism of detection approach. Lamb wave is excited on the surface, and stress wave fields and time-history response of models were extracted and compared. Experimental investigations were carried out to verify the applicability of the proposed approach in practice. A scaled GC specimen was constructed and Lamb wave was excited by the PZT patches mounted on the surface of GC specimen. The output voltage of surface-mounted PZT sensors under different axial loads were compared. Both numerical and experimental results show that the proposed approach is effective to the detection of interface debonding defects. The damage evolution index (DEI) based on wavelet packet energy is defined and it can be adopted to qualitatively determine the initiation and evolution of the damage.

A variable kinematic model for the prediction of capacitance variations in embedded PZT sensors

This paper proposes the use of a two-dimensional refined finite element model, based on the Carrera Unified Formulation (CUF), to predict the variation in capacitance of embedded piezoelectric sensors. The accurate stress field of laminated structures with embedded sensors has been evaluated by exploiting the capabilities of refined layer-wise models. A fully coupled electro-mechanical formulation has been adopted to predict the piezoelectric response of embedded sensors. Different piezoelectric materials have been considered and a parametric analysis has been carried out including geometrical and physical parameters. The results show that the variation in capacitance is highly affected by the through-the-thickness deformations, that is, classical models cannot be used to predict this phenomenon. The variation in the capacitance value has been confirmed by experimental results proposed in the literature and can be used as a parameter for evaluating the internal stress field.

Damage Identification and Localization in an Aluminium Plate Based on Lamb Waves

The article presents a method for identifying and locating damages in an aluminum plate using Lamb waves. For this, a network of PZT wafer type actuators/sensors is used to generate and detect Lamb waves. The damage location algorithm is sketched taking into account the network configuration of PZT sensors. The experimental results confirm the calculation procedure.

Theoretical formulism analyzing damping nature of the ferromagnetic shape memory alloy

The behavior of acoustic stress waves propagated through Ferromagnetic Shape Memory Alloy (FSMA) is formulated theoretically for analyzing their energy-absorbing capability and is validated with experimental measurements. In the experiment, piezostack actuator transfers the series of asymmetric acoustic pulses through Ni48Mn32Ga20 single crystal to induce twin boundary motion. Thereby suppressing the vibration along the sample and are observed using a PZT sensor. Based on these experimental conditions, one dimensional wave function is theoretically derived to numerically compute the damping behavior of Ni48Mn32Ga20 sample. These analyses can be utilized to design a highly efficient and cost-effective damper using an FSMA sample.

Piezo displacement sensors for a compact high-speed x–y nanopositioner in differential actuation mode

An emerging actuation technique in piezo driven nanopositioners is differential actuation, where each axis has two opposing actuators that operate differentially and provide bilateral motion. It has simultaneous benefits of improving linearity and range of displacement. However, few methods for displacement sensing employing in-situ transducers have been considered for this kind of nanopositioners. We address a novel application of PZT piezoelectric chips for direct displacement sensing in differentially driven nanopositioners. First, an electromechanical force analysis is performed in order to increase the PZT sensor sensitivity through the structural design of the nanopositioner. Secondly, the sensing performances of the proposed in-situ PZT sensor are compared with those from an alternative built-in piezoresistive (PZR) strain gauge sensor under equal circumstances, in different sensing and actuation configurations. While the PZR sensor has a larger sensing bandwidth than the PZT one and performs better if the actuation frequency is smaller than 30 Hz, the PZT sensors provides better accuracy when the actuation is well within its sensing bandwidth. The accuracy of the differential sensors and the input-displacement linearity are improved when the mechanical preload force magnitudes on the opposing actuators are balanced. The differential PZT sensor can provide accurate measurements even in a non-differential mode after recalibration.