PZT Sensors Research Articles

Damage detection of structural members using internet of things (IoT) paradigm

Abstract Structural Health Monitoring (SHM) has gained a lot of importance in today’s scenario. Significant reduction in the cost of sensors and connectivity, made remote data collection possible to monitor the structures and perform critical analysis so that actions can be taken to assess and enhance the residual life of the structures. Internet of Things (IoT) is the system of smart sensors that combines sensing and transmission of various responses of the structures to distant servers which continuously processes and monitors these responses. The present paper proposes an integrated platform of IoT for damage detection using a Wi-Fi module, Raspberry Pi, (Piezoelectric) PZT sensors along with Digital to Analog (DAC) and Analog to Digital converters (ADC). Responses from the host structure are extracted by the PZT sensors and a mathematical model is proposed to identify and quantify the damage compared with responses of the healthy structural member. The algorithm is executed using Python in Raspberry Pi. The present work includes testing of simply supported aluminium beam surface bonded with PZT transducers where one is an actuator and the other is a sensor. The beam is excited by a sinusoidal wave through an actuator. The digital wave sent from Raspberry Pi is converted to analog using DAC and excites the beam through the actuator. The responses received from the sensor is converted to digital form using ADC. The responses are initially taken for healthy beam and for the same beam, a sequential increase in crack widths is induced. Responses of the healthy and damaged beam are compared using Cross-Correlation (CC) damage index to identify the extent of the damage. The CC values are analyzed and sent to the cloud where an alert message is sent to mobile if the CC value exceeds the threshold limit.

A High Sensitivity Optical Fiber Interferometer Sensor for Acoustic Emission Detection of Partial Discharge in Power Transformer

We propose a Michelson ultrasonic sensing system for detecting the acoustic emission generated by the partial discharge in power transformer. In order to guide the sensor head design in the sensing system for high sensitivity, a theoretical model is established to investigate the effects of the sensor head dimensions on the response sensitivity. After that, an optimized sensor head is designed. In the frequency range from 80 kHz to 200 kHz, whether the PZT sensor is installed in the oil or on the tank, the average response sensitivity of the proposed sensing system is higher than that of the conventional PZT system. When the distance between the sensor head and ultrasonic source is 300 mm in oil, the average detection limit of the Michelson ultrasonic sensing system is about 0.26 Pa, which is about 18.6% of that of the PZT system. Moreover, experiment results show that the detectable partial discharge initial voltage for the proposed optical system is 21.5% lower than that for the PZT system. The enhanced sensitivity makes the Michelson ultrasonic sensing system a potential method to detect the small defects in power transformer.

Numerical simulation for health monitoring of thin simply supported plate using PZT transducers

PZT (Lead Zirconate Titanate) sensors are primarily used due to their important role in structural condition monitoring mainly in nondestructive evaluation. The electromechanical impedance (EMI) strategy is being developed as a successful tool for basic Damage identification. Local damages and flaws in the structure are characterized by variations in the electromechanical impedance signature pattern of the piezoelectric transducer that is attached to the structure. On Basing EMI techniques, numerical simulations are performed using coupled field finite element analysis on a PZT transducer bonded at various location on homogenous plate simply supported with damage in the center of plate, by inducing stiffness reduction, in ANSYS to obtain admittance signatures. RMSD is used for calculation of damage index among damaged and undamaged states. A parametric investigation of the structural stiffness and position of the PZT provides a detailed understanding of admittance signature analysis.

Vibration measurement of a cutting tool using root-embedded PZT sensor

PurposeIn this paper, a vibration measuring technique that relies on the use of piezoelectric material and is originally developed to measure the vibration of turbine blade is adopted to measure the vibration of cutting tool in turning. The piezoelectric material is embedded at the root of the cutting tool. The scope of this research is to investigate the feasibility of using this technique by first conducting ANSYS simulation to solve the coupled field equations that govern the piezoelectric phenomenon followed by experimental work to compare the measured data with those obtained by conventional method to have an insight into the effectiveness of the adopted technique. Both simulation and experimental results show that the use of an embedded PZT sensor at the root of cutting tool is very useful for measuring vibration and can be used for further cutting operation control. In addition, it has captured more information than conventional vibration measurement techniques.Design/methodology/approachVibration measurement of root-embedded PZT material to convert the dynamic cutting forces into vibration signals that can be used in cutting process optimization and improvement of cutting quality.FindingsPZT material is found to be very responsive to high-frequency vibrations such that it can catch Chatter phenomena and can be used in developing control strategies.Research limitations/implicationsMainly used for turning cutting process in this research. Other manufacturing process like milling special tool holder designs.Practical implicationsCan be used as online monitoring systems for cutting tool holders.Social implicationsEngineer and technician aid in quality assurance and control.Originality/valueThe new approach of embedding PZT material at the cutting tool root and the signals presentation and processing.

Reverberation-based high-speed guided-wave ultrasonic propagation imager for structural inspection of thick composites

Increasing use of thick composite structures in many fields, including the aerospace and shipbuilding industries, necessitates appropriate inspection techniques to ensure structural integrity. Of many nondestructive testing techniques, laser ultrasonic testing is a non-contact method that yields accurate inspection results with high spatial resolution; this method was adopted in this study for the inspection of thick composite structures. We propose a novel guided-wave ultrasonic propagation imaging (UPI) method, called the reverberation wave UPI (R-wave UPI), which is capable of faster target scanning and clearer highlighting of confining waves. To prove the merits of the R-wave UPI, a relatively thin carbon/epoxy composite (thickness, 12 mm) was first tested using the proposed method and the conventional through-transmission UPI. The R-wave UPI modifies the guided-wave UPI with a faster pulse repetition frequency (PRF) laser and ultrasonic energy mapping with straightforward parameter determination. The through-transmission UPI consisting of a raster mechanical scanner, a Q-switched laser, and a laser Doppler vibrometer, was used as a reference, whereas the R-wave UPI consisting of an angular laser mirror scanner, a Q-switched laser, and a PZT sensor was operated at a high PRF in the kilohertz regime to induce reverberation. The reverberation phenomenon was used in the post-image processing, called ultrasonic energy mapping (UEM). UEM with a high PRF was then compared to the through-transmission inspection reference to verify its accuracy and reliability for mapping of structural anomalies. Finally, a thick and curved composite blade with a rough and curved surface that could not be inspected using the conventional through-transmission UPI was tested using 7 kHz PRF and its delamination was successfully visualized using the UEM.

Analytical approach for crack identification of glass fiber reinforced polymer–sea sand concrete composite structures based on strain dissipations

Glass fiber reinforced polymer bars have potential application in the seawater sea sand concrete. In this study, an analytical method was proposed to examine the internal crack development in glass fiber reinforced polymer–sea sand concrete composites. The method was derived by analyzing the strain dissipation and shear-lag behavior. Thus, the internal cracks can be quantitatively identified by the proposed model with Fourier transform analysis. The proposed approach was experimentally verified through pullout tests for the specimens with artificial cracks. The results indicated that the prediction errors were less than 10%. In addition, the piezoelectric sensors were adopted to verify the proposed model. A damage index (DI) defined by the energy loss of received signals was used to characterize cracks inside the composite. Loading test results indicated that the DI-calculated cracks were consistent with the proposed analytical model. Finally, the cyclic loading tests of the glass fiber reinforced polymer composite were conducted using both strain gauges and PZT sensors. The results have shown that the differences between the proposed approach and PZT sensors were less than 15%. Thus, the proposed approach in this study could provide an alternative approach for quantitative evaluation of internal cracks in the glass fiber reinforced polymer–coral sand–cement composites.

Crack damage identification and localisation on metro train bogie frame in IoT using guided waves

The Internet of Things (IoT) is one of the key components of metro train safety as an emerging development approach due to its great potential to advance environmental sustainability. A bogie is a key component for carrying a passenger's vehicle body. Its damage and defects can destroy fluent operations and better service for train operation. The critical problem of traditional non-destructive examination for bogie is the high cost of labour and environment. Because they are in effect only after the whole vehicle has to be split into many sub-components and paint removed. This study provides an IoT approach and practice for bogie crack identification of bogie. The presented method can achieve simple and efficient detection of damage with cheap PZT sensor network. Its advantages is that non-split work and non-removal paint pollution. Compared with traditional detection methods, this method is more sensitive to a small area of internal damage and can identify the level of damage and location of the bogie plate frame even with the dirty and non-smooth surface.

Smart embedded PZT sensor for in-situ elastic property and vibration measurements in concrete

An embeddable PZT-based sensor, which is capable of detecting transient dynamic motion for vibration measurement from a concrete structure, is presented. A circular PZT patch, which provides uniform in-plane sensing capability, is used to develop the sensor. The validity of vibration measurements obtained from the embedded PZT sensor is established using a standard setup. The influence of the orientation of the PZT sensor on capturing the different vibrational modes of the concrete cylinder is studied. The transient dynamic signatures captured from the embedded sensors in a vibration measurement match those obtained from surface mounted accelerometers. The elastic properties of hydrating concrete are determined from the vibration measurements of standard cylinders obtained using the embedded PZT sensors. The ability of the embedded sensors to detect low-level, transient vibration of the concrete structures immediately after setting is demonstrated. The vibration measurements provide a continuous measure of increasing stiffness of an aging concrete medium.

Extrapolation of AR models using cubic splines for damage progression evaluation in composite structures

This paper presents the potentiality of the use of extrapolation of a set of Auto-Regressive (AR) models to inspect a future damage sensitive indices based on changes in one-step-ahead prediction errors. The key idea is to use multiple AR models to assess a data-driven model to represent and predict the time-series outputs of the PZT sensors receiving Lamb waves in a composite coupon. Based on some simplified assumptions, after detecting initial damage using some previous classifier, its progression evaluation by interpolating the AR parameters is proposed and examined based on cubic spline functions. After, an extrapolated AR model using this information may verify the future state and to inspect how the damage could progress. An aeronautical composite panel with bonded piezoelectric elements that act both as sensors and actuators is utilized to examine the relationship between the variation of the identified model parameters with various levels of simulated damage. The results have shown a smooth and adequate correlation between the estimates obtained by the extrapolated model and the actual progress of the damage observed. The significant advantage of the proposed procedure is implementing this task without adopting a complicated and costly mathematical-physical model.

Piezo-electret vibration sensors designed for acoustic-electric guitars

A piezo-electret vibration sensor designed for acoustic-electric guitars is evaluated. A piezo-electret, which is a cellular polypropylene electret film, is laminated with a 150-μm-thick polyethylene terephthalate (PET) film to achieve sufficient durability for general use. Additionally, a 10-μm-thick silver electrode is printed on the top surface as a shield electrode. This electrode adds a mass of only 63 mg to the sensor. The sensor is attached to the soundboard of a guitar body. An impact force is applied to the top of the saddle of the guitar body. The output voltage of the sensor owing to the vibration of the soundboard is measured by a voltage follower and an FFT analyzer. Conventional sensors that use lead zirconate titanate (PZT) ceramics are also tested. The results show that only the piezo-electret sensor detects the vibration of the soundboard over a wide frequency range up to 10 kHz. The time response of the sensor also corresponds to the vibration of the soundboard. However, the output voltage of the sensor is 1/10 to 1/100 of that of the PZT sensors. The effective d 33 value of the sensor is 1.58 pC/N at 1 kHz. The value is only 1/280 of the apparent d 33 value of the piezo-electret, owing to an increase in the effective elastic modulus in the thickness direction caused by lamination with the PET film.

Identification of a moving mass on a beam bridge using piezoelectric sensor arrays

Since overload has become the main potential safety hazard for aging bridges, management of traffic load information is of great significance in safety insurance of bridges. Here, an array of lead zirconium titanate (PZT) sensors is utilized to capture the dynamic responses of beam bridge due to moving load, for which the details are identified based on electromechanical analysis and structural dynamics. The precision and feasibility of the proposed method are validated by experimental tests for a simply supported and a continuous steel beam respectively. Results show that the PZT sensor has the advantage of self-driving, fast response and high precision, which makes it possible for wireless sensing technology. Results also reveal that dynamic responses of the beam can reflect effectively the moving speed and magnitude of the moving force when the load approaches to the mid-span. Furthermore, the proposed method is applicable for different beam structures and insensitive to the noise interference. The current method may provide guidance for bridge moving load identification.

Use of smart intelligent sensor & actuator mechanical materials (PVDF / PZT) in developing MIMO mathematical model of the smart structure and its use to control the active vibrations using discrete sliding mode control theory with output samples

A multi-input, multi-output based modelling of intelligent flexible mechanical aluminium structures using smart materials with Euler-Bernoulli beam theory & state space techniques is being presented with multi-sensor data fusion concepts. An aluminium cantilever beam of rectangular cross section with known specifications is considered for the modelling purposes. To start with, from the fundamental principles of E-B theory, a Lagrange equation of motion is obtained both for the regular beam element as well as for the PZT & PVDF sensor actuator pair. Following which, a dynamic equation of motion of the smart intelligent structure developed using the smart materials consisting of PZT& PVDF is obtained. The dynamic equation is transformed into a state space model with 2 i/o’s using the concepts of state space theory in control engineering. The model is developed considering the first 2 modes of vibration, which are the most dominant modes in the vibration theory. The developed state space model is used for active vibration control. An external force of 1 N is applied at the end of the smart flexible multivariable multimodel cantilever beam after which the beam is subjected to vibrations. A Discrete Sliding Mode Control (DSMC) based controller on the o/p samples is designed and put in loop with the plant, after which the plant vibrations decays to zero in no time. The mathematical model of the DSMC controller is used to control the vibrations of the plant using the concept of destructive interference. The mathematical model of the DSMC controller can be used to control the vibrations of the plant using the concept of destructive interference.

Development of mathematical model for smart intelligent flexible structures using smart intelligent sensor & actuator materials using Timoshenko beam theory & its control using POF

In this research paper, the multivariable modelling of intelligent flexible aerospace structures using smart materials with Timoshenko beam theory & state space techniques with multi-sensor data fusion concept & its control using POF strategy is presented in n this research article. Finite Element Method is used in the analysis also. An aerospace aluminum cantilever beam of rectangular cross section with known specifications is considered for the modelling purposes. To start with from the fundamental principles of Timoshenko beam theory, a Lagrange equation of motion is obtained both for the regular beam element as well as for the PZT & PVDF sensor actuator pair. Following which, a dynamic equation of motion of the smart intelligent structure developed using the smart materials consisting of PZT & PVDF is obtained. Smart materials have got some special properties that react to the changes in their environmental conditions. This means that some of their special properties can be changed by using an external condition, such as temperature, light, pressure, electricity, voltage, pH, or chemical compounds, which could be considered as the special characteristics and this change is reversible, which can be repeated many times. The dynamic equation is transformed into a state space model with 2 inputs and 2 outputs using the concepts of state space theory in the advanced control engineering. The model is developed considering the first 2 modes of vibration, which are the most dominant modes in the vibration theory. The developed state space model is used for active vibration control. The effect of shear is considered in modelling here, which is neglected in case of Euler – Beam theory, thus giving an accurate beam model. An external force of 1 N is applied at the end of the smart flexible multivariable multimodel cantilever beam after which the beam is subjected to vibrations. A POF controller can be designed and put in loop with the plant, after which the plant vibrations decays to zero in no time. The mathematical model of the POF controller can be used to control the vibrations of the plant using the concept of destructive interference. The work done can also be compared with others to show the authenticity or the profoundness of the methodology that is being developed by us.

Multivariable modelling of intelligent flexible mechanical structures using smart materials with FEM, Euler-Bernoulli beam theory, state space & multi-sensor data fusion techniques

In this research paper, the multivariable modelling of intelligent flexible mechanical structures using smart materials with Euler-Bernoulli beam theory & state space techniques is being presented with multi-sensor data fusion concept. To start with from the fundamental principles of E-B theory, a Lagrange equation of motion is obtained both for the regular beam element as well as for the PZT & PVDF sensor actuator pair. Following which, a dynamic equation of motion of the smart intelligent structure developed using the smart materials consisting of PZT& PVDF is obtained. Smart materials have got some special properties that react to the changes in their environmental conditions. This means that some of their special properties can be changed by using an external condition, such as temperature, light, pressure, electricity, voltage, pH, or chemical compounds, which could be considered as the special characteristics and this change is reversible, which can be repeated many times. The dynamic equation is transformed into a state space model with 2 inputs and 2 outputs using the concepts of state space theory in the advanced control engineering. The model is developed considering the first 2 modes of vibration, which are the most dominant modes in the vibration theory. The developed state space model is used for active vibration control. An external force of 1 N is applied at the end of the smart flexible multivariable multimodel cantilever beam after which the beam is subjected to vibrations. A Periodic Output Feedback controller can be designed and put in loop with the plant, after which the plant vibrations decays to zero in no time. The work done can also compared with others to show the authenticity or the profoundness of the methodology that is being developed by us.

Effect of the physical parameters of longitudinally polarized PZT tubes on PZT sensors

Lead zirconium titanate (PZT) sensors have been investigated in various fields. Related research focuses mainly on experiments, analyses are hardly conducted in PZT parameters and PZT sensor performance. In order to improve the PZT sensors’ performance from PZT structural parameter design, simulations on PZT tube’s deformations and resonance frequencies are conducted and analyzed, PZT-fiber Bragg grating (FBG) voltage sensors with different PZT tubes are established for validation tests. It is found in simulation results that the applied voltage range can be decided by polarized direction parameter, and the lowest resonance frequency of PZT tubes, which is decisive to sensor flat frequency response range, are closely related to tubes’ radial parameters. It is also indicated in PZT-FBG sensor tests that PZT’s coupled efficiency with other sensing elements is also an important concern to sensor performance. PZT tube parameter design suggestions for different sensing purposes and for PZT-FBG voltage sensor enhancement are proposed at last. Results in this paper can also be a reference for PZT sensors’ performance enhancement with PZT tubes.

Piezoelectric cement sensor-based electromechanical impedance technique for the strength monitoring of cement mortar

Piezoelectric cement is a 0–3 type cement-based piezoelectric composite comprising 50% lead zirconate titanate (PZT) particles. Piezoelectric cement sensors, which are based on the electromechanical impedance (EMI) technique, are applied for the structural health monitoring (SHM) of cementitious materials. The compressive strength (fc) of three cement mortar types with water-to-cement ratios of 0.4, 0.5, and 0.6 were monitored for 56 days using an embedded piezoelectric cement sensor (PEC sensor). The PZT sensor was used as a counterpart in the experiments. The results indicate that the strength monitoring capability of the PEC sensor is similar to that of the PZT sensor. However, the monitoring capability of the PEC sensor is superior to that of the PZT sensor because the electrical impedance change of the PEC sensor is more evident. The PEC sensor is easy to find an effective monitoring frequency at which the conductance decreases with the age of the cementitious materials because it has the advantage of a broader frequency bandwidth that provides higher recognizing ability than the PZT. For the PEC sensor, a conductance root mean square deviation GR in a high frequency region, such as that higher than 800 kHz, can promote the reliability of mortar strength monitoring. Based on the GR value calculated at the effective monitoring frequency, the relation between fc and GR in the mortar presents a logarithmic behavior. The PEC sensor is suitable for monitoring the change in material properties, especially for cementitious materials.

Design and Experimental Analysis of Composite Material with Piezoelectric Layer

The main objective of this work is to analyze the active vibration control using smart sensors and actuators in a laminated E-Glass/epoxy cyanate composite beam. The cantilevered composite beam has piezoelectric ceramic patches as smart sensors and actuators. Hand layup technique for vibration suppression is done on the fabricated E-Glass/Epoxy-cyanate composite laminated beam. Experimental modal testing is performed to achieve vibration suppression on the flexible composite beam bonded with seven circular type piezoelectric actuator elements and seven circular type sensor elements. The complete vibration suppression utilizes a data acquisition system, a real-time control system, and a functional generator, in addition to the composite beam with PZT sensor and actuator. The data acquisition hardware consists of model NI 9233 (4 channel +5 V 24 Bit IEPE Analog input I2VA 1-to earth ground).

Modal Propellant Gauging in Microgravity

Since 2008, the Modal Propellant Gauging (MPG) team, consisting of multidisciplinary undergraduate researchers from Carthage College, has been developing and testing a fuel gauging system for use in microgravity environments. Using Experimental Modal Analysis (EMA) techniques, the goal of the MPG project is to develop a flight ready technology that gauges fuel in microgravity environments by correlating the modal response of a 1-g equilibrium surface to the microgravity surface response at the same fluid fill level. The technology has been tested aboard parabolic flights via a manned parabolic flight payload. The payload consists of two propellant tanks and is designed to measure the modal response of each propellant tank to an injected white noise signal via PZT sensors. Flight data shows that the MPG method can measure fuel with greater than or equal to 1% resolution at and below 50% fill levels. Under funding from the Wisconsin Space Grant Consortium during the summer of 2018 and 2019, the MPG team made improvements to the Blue Origin New Shepard research flight payload which saw flight on the New Shepard vehicle in January of 2019 and is manifested to fly again in December of 2019.

Monitoring of Grouting Compactness in Tendon Duct Using Multi-Sensing Electro-Mechanical Impedance Method

The structural integrity of post-tensioning prestressed concrete structures with tendon ducts highly depends on the grouting quality in construction. This paper proposes a real-time approach to monitoring the grouting compactness in tendon ducts using the multi-sensing electro-mechanical impedance (EMI) method. When Lead Zirconate Titanate (PZT) transducers with different pre-selected dimensions are serially connected and mounted on a structure at distributed locations, each PZT provides unique resonance frequency coupled with the local structural physical property. Therefore, the impedance with multiple peaks of the serially connected multiple PZTs can be captured during a single measurement, which significantly simplifies the measurement procedure and reduces the data processing time. In addition, the wiring for the PZT sensors is also simplified. In this research, the feasibility of the proposed method was experimentally and numerically investigated to monitor the grouting compactness in a tendon duct specimen. The 3-dB mean absolute percentage deviation (MAPD) was applied to quantify the variations of the impedance signatures measured from five different grouting levels. Both experimental and numerical results verify the feasibility of using the proposed method for monitoring the grouting compactness in tendon ducts.

Damage‐sensitive impedance sensor placement on multi‐strand anchorage based on local stress variation analysis

An important issue in impedance-based damage monitoring is to deploy sensors in proper positions in which damage-sensitive impedance responses can be captured effectively. In this study, a full-scale multi-strand anchorage is analyzed to determine optimal locations of piezoelectric sensors for impedance-based monitoring of locally damaged strands. First, stress variations of the multi-strand anchorage are experimentally measured to estimate the anchorage behavior under the effect of locally damaged strands. Strain signals are examined for axial, circumferential, and radial stress components under the variation of prestress forces. Second, a finite element analysis is made on the multi-strand anchorage to back up the experimental findings. Third, a damage-sensitive structural model is interpreted for the local strand breakage. Finally, impedance responses sensitive to local strand breakage are experimentally examined for a few scenarios simulated in the anchorage system. PZT (lead zirconate titanate) sensors deployed on the anchor head and the bearing plate are evaluated to comparatively determine ideal regions of interest for impedance monitoring. The results show that the greater stress variation yields the greater variations in impedance responses and the near-top and near-anchor heads are ideal regions of interest for damage-sensitive impedance monitoring.