Genetic algorithm based reconstruction of the elastic moduli of orthotropic plates using an ultrasonic guided wave single-transmitter-multiple-receiver SHM array
TL;DR: In this article, a single-transmitter-multiple-receiver (STMR) compact structural health monitoring (SHM) array is used to reconstruct the elastic moduli of orthotropic plate structures.
Abstract: The reconstruction of all nine unknown elastic moduli of orthotropic plate structures has been achieved using a single-transmitter-multiple-receiver (STMR) compact structural health monitoring (SHM) array. This method uses the velocity measurement of the fundamental guided Lamb wave modes (S0 and A0), generated from a central transmitter, and received by a sparse array of receivers that encircle the transmitter. The measured velocities are then used in an inversion algorithm based on genetic algorithms. A prototype compact STMR array was developed and used in the measurement. Simulated data were used to demonstrate the feasibility of the technique. Experiments were conducted on 3.15 mm graphite–epoxy composite plate using a PZT based STMR array as well as laser vibrometer based displacement measurement. Experimental Lamb wave velocity data were used to validate the present technique. This technique finds application in the areas of material characterization and SHM of anisotropic plate-like structures used in aerospace and automobile components made using fiber reinforced composites.
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05 Mar 2010
TL;DR: In this article, the authors used the Lamb wave S0 and A0 mode signals that are reflected from features in the structure such as edge of the plate, bolt holes, etc that are known apriori using STMR array and then reconst
Abstract: Structural health monitoring of plate like structures, using transducer arrays located suitably on the structure, finds applications in monitoring aerospace structures These plates are anisotropic, with wave propagation properties varying with direction Single Transmitter Multiple Receiver (STMR) arrays have been shown before to have the ability to locally characterize the stiffness properties of a composite material with anisotropy The STMR arrays have also been demonstrated for SHM applications using phase reconstruction techniques The guided ultrasonic Lamb waves are used where the central piezoelectric wafer‐active sensor (PWAS) emits the guided waves, and the other PWAS sensors receive the Lamb wave signals In the current work, this technique has been extended to the determination of global elastic moduli using the Lamb wave S0 and A0 mode signals that are reflected from features in the structure such as edge of the plate, bolt holes, etc that are known apriori using STMR array and then reconst
3 citations
10 Mar 2008
TL;DR: In this article, a flexible Printed Circuit Board (PCB) based patch was developed for SHM of aluminum and composite plates, which can provide a means for the in-situ measurement of changes in the elastic moduli during the life time monitoring of structures.
Abstract: The Single Transmitter Multiple Receiver (STMR) array based Structural health monitoring (SHM) technique has been introduced for evaluation of isotropic and anisotropic plate like structures. SHM is carried out by utilizing a phased addition reconstruction algorithm for imaging damage in large plate‐like structures. A flexible Printed Circuit Board (PCB) based patch was developed for SHM of aluminum and composite plates. Additionally, an elastic moduli reconstruction algorithm is described here, using the PCB array patch, which can be applied in at least two cases; (a) for SHM applications, the leave‐in‐place compact array can provide a means for the in‐situ measurement of changes in the elastic moduli during the life time monitoring of structures, thereby providing velocity data for the phased addition reconstruction algorithm, and (b) for materials characterization, where the compact array can be developed as a portable sensor for the measurement of elastic moduli of in‐service and as‐fabricated structu...
2 citations
Cites background or methods from "Genetic algorithm based reconstruct..."
...Lamb wave propagation characteristics and elastic moduli are related by the Rayleigh-Lamb equation for anisotropic material [3, 4]....
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...The phase velocity of these two modes is calculated as discussed in [4]....
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...The applicability of the reconstruction method used in this work has been explained in [4]....
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...the error in the reconstructed elastic moduli is more for some of the elastic moduli which are less sensitive to the velocity [4]....
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TL;DR: The genetic optimization is employed to update an existing law of flexural rigidity in order to minimize the difference between the measured and predicted deflections; measurements will be considered from different time periods.
Abstract: The real response of a given structure, such as deflection, generally differs from prediction obtained from theoretical models. Hence, the need of periodic or long-term structural monitoring has become mandatory. The present paper describes an approach to localize the most suitable period to perform deflection monitoring in case of reinforced concrete bridges. The searched period allows making the best updates of theoretical models to better represent the structural behaviour with time. So, the genetic optimization is employed to update an existing law of flexural rigidity in order to minimize the difference between the measured and predicted deflections; measurements will be considered from different time periods. The proposed methodology is applied to a representative set of 21 RC T-beam bridges with variable parameters. Simulated measurements of static deflections based on weigh-in-motion data collected in some European countries are used in the application.
2 citations
30 Nov 2020
TL;DR: In this paper, a numerical procedure is presented for the material properties estimation using circular surface mounted piezoelectric transducers that can be used for material characterization or calibration of numerical models.
Abstract: The design and development of robust and reliable guided wave Structural Health Monitoring systems require accurate information of the structure’s material properties. This is needed by various analysis tools for the determination of wave propagation characteristics in order to evaluate and optimize the system’s performance. Estimation of the mechanical properties of composite materials using Lamb wave measurements is not straightforward as it requires the solution of an inverse problem. In this study, a numerical procedure is presented for the material properties estimation. The aim is to obtain estimates of the unknown material properties using circular surface mounted piezoelectric transducers that can be used for material characterization or calibration of numerical models. The procedure utilizes the Semi-analytical finite element method for the efficient computation of the dispersion curves and a genetic algorithm for the extraction of the material properties that fit best the experimental observations.
2 citations
2 citations
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TL;DR: This paper is intended to serve as a summary review of the collective experience the structural engineering community has gained from the use of wireless sensors and sensor networks for monitoring structural performance and health.
Abstract: In recent years, there has been an increasing interest in the adoption of emerging sensing technologies for instrumentation within a variety of structural systems. Wireless sensors and sensor networks are emerging as sensing paradigms that the structural engineering field has begun to consider as substitutes for traditional tethered monitoring systems. A benefit of wireless structural monitoring systems is that they are inexpensive to install because extensive wiring is no longer required between sensors and the data acquisition system. Researchers are discovering that wireless sensors are an exciting technology that should not be viewed as simply a substitute for traditional tethered monitoring systems. Rather, wireless sensors can play greater roles in the processing of structural response data; this feature can be utilized to screen data for signs of structural damage. Also, wireless sensors have limitations that require novel system architectures and modes of operation. This paper is intended to serve as a summary review of the collective experience the structural engineering community has gained from the use of wireless sensors and sensor networks for monitoring structural performance and health.
1,497 citations
TL;DR: In this paper, the capability of embedded piezoelectric wafer active sensors (PWAS) to excite and detect tuned Lamb waves for structural health monitoring is explored.
Abstract: The capability of embedded piezoelectric wafer active sensors (PWAS) to excite and detect tuned Lamb waves for structural health monitoring is explored. First, a brief review of Lamb waves theory is presented. Second, the PWAS operating principles and their structural coupling through a thin adhesive layer are analyzed. Then, a model of the Lamb waves tuning mechanism with PWAS transducers is described. The model uses the space domain Fourier transform. The analysis is performed in the wavenumber space. The inverse Fourier transform is used to return into the physical space. The integrals are evaluated with the residues theorem. A general solution is obtained for a generic expression of the interface shear stress distribution. The general solution is reduced to a closed-form expression for the case of ideal bonding which admits a closed-form Fourier transform of the interfacial shear stress. It is shown that the strain wave response varies like sin a, whereas the displacement response varies like sinc a. ...
890 citations
TL;DR: In this article, a new technique is developed to determine the dispersion relation and the propagational speeds of waves in dispersive solids, which can be applied to measurements of acoustic or electromagnetic wave speeds in other dispersive media.
Abstract: A new technique is developed to determine the dispersion relation and the propagational speeds of waves in dispersive solids. The phase spectrum of a broadband pulse is linearly related to the dispersion relation of the dispersive medium. The method is simpler than the continuous‐wave phase comparison technique. Application is made to measure the phase and group velocities of waves in fiber‐reinforced composite materials and in thin wires. This technique is expected to be applicable to measurements of acoustic or electromagnetic wave speeds in other dispersive media.
476 citations
TL;DR: In this paper, a piezoelectric-based built-in diagnostic technique has been developed for monitoring fatigue crack growth in metallic structures, which consists of three major components: diagnostic signal generation, signal processing and damage interpretation.
Abstract: A piezoelectric based built-in diagnostic technique has been developed for monitoring fatigue crack growth in metallic structures. The technique uses diagnostic signals, generated from nearby piezoelectric actuators built into the structures, to detect crack growth. It consists of three major components: diagnostic signal generation, signal processing and damage interpretation. In diagnostic signal generation, appropriate ultrasonic guided Lamb waves were selected for actuators to maximize receiving sensor measurements. In signal processing, methods were developed to select an individual mode for damage detection and maximize signal to noise ratio in recorded sensor signals. Finally, in damage interpretation, a physics based damage index was developed relating sensor measurements to crack growth size. Fatigue tests were performed on laboratory coupons with a notch to verify the proposed technique. The damage index measured from built-in piezoceramics on the coupons showed a good correlation with the actual fatigue crack growth obtained from visual inspection. Furthermore, parametric studies were also performed to characterize the sensitivity of sensor/actuator location for the proposed technique.
476 citations
TL;DR: In this article, a non-contact method for low-frequency Lamb wave sensing using a laser Doppler velocimeter is presented, and the results are validated using classical piezoceramic-based sensing and numerical simulations.
Abstract: Structural health monitoring using Lamb waves is based on guided waves introduced to a structure at one point and sensed at a different location. Actuation and sensing can be accomplished using various types of transducer. The paper demonstrates a non-contact method for low-frequency Lamb wave sensing. The technique utilizes a laser Doppler velocimeter. Lamb wave responses are enhanced using data smoothing and filtering procedures. The results are validated using classical piezoceramic-based sensing and numerical simulations. The study shows the potential of laser vibrometry for Lamb wave sensing.
301 citations