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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TL;DR: In this paper, an inverse procedure based on stress guided waves is proposed for the characterization of the elastic moduli of composite plates, which is carried out via genetic algorithms by minimizing the discrepancy between experimental and numerical group delay curves for different directions of propagation along the plate.
Abstract: In this study, an inverse procedure based on stress guided waves is proposed for the characterization of the elastic moduli of composite plates. The characterization is carried out via genetic algorithms by minimizing the discrepancy between experimental and numerical group delay curves for different directions of propagation along the plate. Experimentally, for a given distance source–receiver, the group delay curves are obtained by processing the guided waves time–transient signals via a time–frequency transform. For the same distance, a fast and reliable semi-analytical finite element formulation is used for the forward computation of the group delay curves. Here, pseudo-experimental data, generated by means of the semi-analytical finite element model for an assumed known set of elastic coefficients, are used to test the reliability of the proposed procedure. The results obtained for three different plates are promising. Since semi-analytical finite element formulations can also handle plates with unif...
37 citations
TL;DR: In this article, the first-ever implementation of an inverse modeling technique on the basis of a genetic optimization scheme in order to extract quantita- tive information from a pulsed ultrasonic polar scan (P-UPS) was reported.
Abstract: Already in the early 1980's, it has been conjectured that the pulsed ultrasonic polar scan (P-UPS) provides a unique fingerprint of the underlying mechanical elasticity tensor at the insonified material spot. Until now, that premise has not been thoroughly investigated, nor validated, despite the opportunities this would create for NDT and materials science in general. In this paper, we report on the first-ever implementation of an inverse modeling technique on the basis of a genetic optimization scheme in order to extract quantita- tive information from a P-UPS. We validate the optimization approach for synthetic data, and apply it to experimentally obtained polar scans for annealed aluminum, cold rolled DC-06 steel as well as for carbon fiber reinforced plastics. The investigated samples are plate-like and do not require specific preparation. The inverted material characteristics show good agreement with literature, micro-mechanical models as well as with results obtained through conventional testing procedures.
36 citations
TL;DR: In this paper, the authors examined the potential of ultrasonic guided waves to identify the elastic properties of fiber-reinforced composite laminates widely used in light-weight structures and proposed a property inversion scheme based on matching phase velocity dispersion curves of relevant guided modes by means of a Simulated Annealing optimization algorithm and a Semi-Analytical Finite Element method.
36 citations
TL;DR: In this paper, an approach to non-destructive evaluation of laminate composite plate elastic properties based on piezoelectrically induced elastic guided waves and laser Doppler vibrometry is presented and discussed.
34 citations
TL;DR: In this paper, the stiffness coefficients of two different composites were reconstructed by inverting the measured Lamb wave phase velocities through genetic algorithms, by minimizing the error between the calculated and the measured velometres.
28 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