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 article, an inverse procedure based on the propagation of guided ultrasonic waves is proposed for the characterization of the elastic material constants of plates, which consists of an optimization problem in which the discrepancy between the dispersion curves obtained through a semi analytical finite element (SAFE) formulation and numerical or experimental dispersion curve is minimized.
82 citations
TL;DR: In this article, two flexible printed circuit board (PCB)-based patches were developed for accomplishing both objectives, i.e. online material characterization (MC) and structural health monitoring (SHM) of anisotropic plate-like structures.
Abstract: Structural health monitoring (SHM) of plate-like structures used in aerospace industries, using transducer arrays located suitably on the structure, such as the single-transmitter multiple-receiver (STMR) array [Wilcox PD, Lowe M, Cawley P. Lamb and SH wave transducer arrays for the inspection of large areas of thick plates. Review of progress in quantitative nondestructive evaluation, vol. 19A. Melville, NY, USA: American Institute of Physics; 1999. p. 1049–56; Wilcox PD. Guided wave beam steering from omni-directional transducer arrays. Review of progress in quantitative nondestructive evaluation, vol. 22A. Melville, New York, USA: American Institute of Physics; 2002. p. 761–8], has been demonstrated here. The reconstruction of the material state was carried out by utilizing a phased addition reconstruction algorithm. In addition to the signals from damage sites, the ultrasonic guided wave-based reconstruction procedures also need the complete set of elastic moduli as a continuous input throughout the SHM process. In the present study, two flexible printed circuit board (PCB)-based patches: ((i). single-quadrant, double-ring STMR material characterization (MC) array and (ii). Full-ring STMR SHM array) were developed for accomplishing both objectives, i.e. (a) online MC and (b) SHM of anisotropic plate-like structures, respectively. Experiments were conducted on 3.15 mm graphite-epoxy composite plate using PCB-based STMR arrays, the feasibility of accomplishing both objectives was demonstrated.
48 citations
TL;DR: A review on the development of nondestructive vibrational evaluation approaches in identifying the elastic constants of composite plates, in experimental and numerical manners, in order to enlighten researchers with the current trends of nonsmooth vibrational approaches is presented in this article.
Abstract: Destructive identification approaches are no longer in favor since the advent of nondestructive evaluation approaches, as they are accurate, rapid, and cheap. Researchers are devoted to improving the accuracy, rate of convergence, and cost of such approaches, which depend greatly on the types of vibrational experiments conducted and the types of forward and inverse methods used in numerical section. Therefore, this article presents a review on the development of nondestructive vibrational evaluation approaches in identifying the elastic constants of composite plates, in experimental and numerical manners in order to enlighten researchers with the current trends of nondestructive vibrational approaches.
44 citations
TL;DR: An algorithm to compute specific parts of the dispersion curves for elastic waveguides based on an axisymmetric representation of the Scaled Boundary Finite Element Method.
43 citations
TL;DR: This paper introduces an efficient inversion method based on genetic algorithms using multimode guided waves, in which the mode-order is kept blind, and shows that the model parameters are in good agreement with the reference values derived from x-ray micro-computed tomography.
Abstract: Recent progress in quantitative ultrasound has exploited the multimode waveguide response of long bones. Measurements of the guided modes, along with suitable waveguide modeling, have the potential to infer strength-related factors such as stiffness (mainly determined by cortical porosity) and cortical thickness. However, the development of such model-based approaches is challenging, in particular because of the multiparametric nature of the inverse problem. Current estimation methods in the bone field rely on a number of assumptions for pairing the incomplete experimental data with the theoretical guided modes (e.g. semi-automatic selection and classification of the data). The availability of an alternative inversion scheme that is user-independent is highly desirable. Thus, this paper introduces an efficient inversion method based on genetic algorithms using multimode guided waves, in which the mode-order is kept blind. Prior to its evaluation on bone, our proposal is validated using laboratory-controlled measurements on isotropic plates and bone-mimicking phantoms. The results show that the model parameters (i.e. cortical thickness and porosity) estimated from measurements on a few ex vivo human radii are in good agreement with the reference values derived from x-ray micro-computed tomography. Further, the cortical thickness estimated from in vivo measurements at the third from the distal end of the radius is in good agreement with the values delivered by site-matched high-resolution x-ray peripheral computed tomography.
38 citations
References
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TL;DR: In this article, the integration of laser and fiber optic methods for generating and detecting broadband, transient Lamb waves in a steel plate is described, and the generated Lamb waves are shown to be a superposition of different Lamb modes including the zeroth-order symmetric together with the first-order antisymmetric modes.
Abstract: This Letter describes the integration of laser and fiber optic methods for generating and detecting broadband, transient Lamb waves in a steel plate. The generated Lamb waves are shown to be a superposition of different Lamb modes including the zeroth‐order symmetric together with the zeroth‐ and first‐order antisymmetric modes. Signal processing techniques are used to extract the phase velocities for each of these modes over a continuous, broadband frequency spectrum from the transient time histories of the waves recorded at two locations on a steel plate. The results are found to be in excellent agreement with theoretical phase velocities for each of the three modes evaluated.
30 citations
TL;DR: In this article, a simple method for measuring Lamb wave phase velocities is used to obtain data for the lowest symmetric Lamb mode (S0) and the lowest antisymmetric Lamb modes (A0) for composite laminates.
Abstract: A simple method for measuring Lamb wave phase velocities is used to obtain data for the lowest symmetric Lamb mode (S0) and the lowest antisymmetric Lamb mode (A0) for composite laminates. The experimental data are compared with the results from an approximate theory for the lowest Lamb modes in the low frequency, long wavelength region for a unidirectional laminate, a symmetric cross-ply laminate, a symmetric quasi-isotropic laminate and an aluminum plate. There is good correlation between the data and the results from the approximate theory, which suggests that the approximate theory works well in the low frequency, long wavelength region in these cases. Also, this experimental procedure of measuring phase velocities of the lowest symmetric and antisymmetric modes can be used to characterize laminated composite plates with and without damage since each material and stacking sequence gives distinct lowest symmetric and antisymmetric curves.
29 citations
TL;DR: In this paper, the authors present a technique to identify elastic parameters of composite materials based on model updating involving an optimization process in which the objective function is defined as the difference between analytical natural frequencies and their experimental counterparts.
Abstract: The aim of this work is to present a technique to identify elastic parameters of composite materials. The identification is based on model updating involving an optimization process in which the objective function is defined as the difference between analytical natural frequencies and their experimental counterparts. Such analytical natural frequencies are obtained by means of the finite element method while the experimental ones are obtained by standard modal tests. The optimization problem is solved by a genetic algorithm (GA), which does not require the cost function gradient avoiding the expensive eigenvectors computation presents in gradient methods. The proposed technique is assessed by a number of different tests.
20 citations
TL;DR: In this paper, a nonlinear inverse method was proposed to determine the second and third order elastic constants for a caesium dihydrogen phosphate lattice via ultrasonic velocity measurements.
Abstract: This paper describes a nonlinear inverse method which allows the determination of the second- and third-order elastic constants for a caesium dihydrogen phosphate lattice via ultrasonic velocity measurements. This analysis is based on a genetic algorithm. The efficiency and accuracy of the method and the influence of measurement errors are discussed.
20 citations
01 Jan 1990
TL;DR: In this article, the loci of the reflection coefficient (RC) zeroes as functions of frequency and angle of ultrasonic wave incidence were investigated for fluid-loaded composite plates.
Abstract: Recently there have been intensive studies [1,2,3] of the coefficient of reflection of ultrasonic waves from fluid-loaded composite plates. Attention has been given mainly to the loci of the reflection coefficient (RC) zeroes as functions of frequency and angle of ultrasonic wave incidence. Interest in the RC zeroes (maxima of the transmission coefficient) arose originally from their association with the leaky Lamb waves in the plate which is valid only for low fluid densities [4]. Independently of the physical meaning of the RC zeroes the spectrum carries important information on the properties of the composite and may be used for reconstruction of the elastic constants from the experimental data [5,6].
17 citations