Papers by Keyword: Damage Localization

Paper TitlePage

Authors: Chen Ning Cai, Gang Yan
Abstract: This paper presents a genetic algorithm (GA)-based approach for localizing damage in plate-like structure. Diagnostic Lamb wave is excited into structure before and after damage to obtain scattered wave that contain characteristic information of the damage. After the time-of-flight (ToF) of the scattered wave in each actuator-sensor path is measured by continuous wavelet transform (CWT), a GA optimization procedure is developed to adaptively identify the location of damage without knowing the material properties a priori. It is achieved by minimizing the difference between the measured and calculated ToF of the scattered Lamb wave. Experimental study for an aluminium plate is conducted to validate the proposed damage localization approach.
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Authors: Madhuka Jayawardhana, Xin Qun Zhu, Ranjith Liyanapathirana, Upul Gunawardan
Abstract: High energy consumption, excessive data storage and transfer requirements are prevailing issues associated with structural health monitoring (SHM) systems, especially with those employing wireless sensors. Data compression is one of the techniques being explored to mitigate the effects of these issues. Compressive sensing (CS) introduces a means of reproducing a signal with a much less number of samples than the Nyquist's rate, reducing the energy consumption, data storage and transfer cost. This paper explores the applicability of CS for SHM, in particular for damage detection and localization. CS is implemented in a simulated environment to compress SHM data. The reconstructed signal is verified for accuracy using structural response data obtained from a series of tests carried out on a reinforced concrete (RC) slab. Results show that the reconstruction was close, but not exact as a consequence of the noise associated with the responses. However, further analysis using the reconstructed signal provided successful damage detection and localization results, showing that although the reconstruction using CS is not exact, it is sufficient to provide the crucial information of the existence and location of damage.
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Authors: Alberto Carpinteri, Giuseppe Lacidogna, Gianni Niccolini
Abstract: Extensive research and studies on concrete fracture and failure have shown that concrete should be viewed as a quasi-brittle material having a size-dependent behaviour. Numerous experimental techniques have been employed to evaluate fracture processes, and a number of modelling approaches have been developed to predict fracture behaviour. The non-destructive method based on the Acoustic Emission (AE) technique has proved highly effective, especially to check and measure the damage phenomena that take place inside a structure subjected to mechanical loading. In this paper an experimental investigation conducted on concrete and RC structures by means of the AE technique is described. The AE signals reflecting the release of energy taking place during the damage process were recorded and micro-cracking sources were localised by measuring time delays by means of spatially distributed AE sensors.
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Authors: Dong Hwan Lee, Ju Won Kim, Chang Gil Lee, Seung Hee Park, Jong Jae Lee
Abstract: In this study, a MFL (Magnetic Flux Leakage) based 3D inspection system which is incorporated into a cable climbing robot was investigated to monitor the healthy condition of steel cables. Firstly, a MFL sensor head prototype composed of two permanent magnets and eight hall sensors was designed and fabricated. A steel cable specimen with several types of damage, such as corrosion and cutting, was inflicted and scanned by the MFL sensor head to measure the magnetic flux density of the specimen. The measured MFL signals were used to interpret the healthy condition of the steel cable. For improving the resolution and quantification of the damage level, digital signal processing techniques were performed. In addition, the measured MFL signals were visualized into a 3D MFL map for real-time and online cable monitoring. This visualized MFL map can provide the information about location, shape and size of damages very intuitively. Finally, the results were compared with information on actual inflicted damages to confirm the accuracy and effectiveness of the MFL based cable inspection system.
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Authors: Tomasz Wandowski, Pawel Malinowski, Wiesław M. Ostachowicz
Abstract: In this paper algorithm for damage localisation in thin panels made of aluminium alloy has been proposed. Mentioned algorithm uses Lamb wave propagation methods and geometrical approach for damage localisation. Elastic waves are generated and received using piezoelectric transducers. Excited elastic waves propagate and reflect from panel boundary and discontinuities existing in the panel. Wave reflection can be registered through the piezoelectric transducers and used in signal processing algorithm. Processing algorithm consists of two parts: signal filtering and extraction of damage location. The first part is used in order to remove noise from received signals. Second part allows to extract arrival time of waves reflected from discontinuity, very often called Time Of Flight (TOF). Localisation algorithm uses pairs of transducers from a concentrated transducers configuration. Using signals from pair of transducers two times of reflection can be extracted from received signals. Because coordinates of transducers are well known ellipse can be constructed based on extracted times of waves reflections. Damage lies one ellipse but it is not known exactly where. Therefore one ellipse is not enough to localise a discontinuity. In order of proper damage localisation more ellipses must be used. In this purpose signals received by larger number of transducers pairs are used in damage localisation algorithm. Points of ellipses intersections allow to indicate localisation of damage. Described signal processing algorithm has been coded in the MATLAB® environment. In this work experimental results has been presented.
87
Authors: Hui Fang
Abstract: This paper presents a new method for the damage localization and severity estimate for lattice material based on substructure modal energy. The significant advantage associated with new method over traditional modal energy methods is that the spatially complete mode shape isn’t needed. Additionally, the new method does not require the analytical and measured modes to be consistent in scale, or to be normalized. Numerical studies in this paper are conducted for lattice material based on synthetic data generated from finite element models.
789
Authors: Sheng En Fang, Ricardo Perera, Maria Consuelo Huerta
Abstract: An environmental excitation having random characteristics may be more effective and cost-efficient than other excitation means for non-destructive damage identification purpose on most of the large-scale engineering structures under operation. In general, many existing damage indexes are constructed based on the modal properties derived firstly from the power spectral density (PSD) analysis of the structures under random excitation. However, the derivation procedures for the modal parameters usually introduce some extra errors into the indexes. This paper aims to propose a simple and feasible damage location index (DLI) constructed directly derived from the analysis results of the structural response PSD. The performance of DLI was verified using an aluminum beam with fixed ends and an experimental reinforced concrete (RC) beam under free boundary condition. Our results show that the damage location of the aluminum beam can be determined via the plot of DLI value by selecting the peaks with the amplitudes exceeding a predefined threshold value in both single- and multi-damaged scenarios. And the index may also predict the possible damage zones in the RC beam experimentally tested.
589
Authors: Jia Wei Zhu, Dan Ting Zhou, Qiu Wei Yang
Abstract: Using the static displacement data, this paper presented a damage localization method for a continuous beam. This method is based on the estimation of changes in the static displacements of the structure. The most significant advantage of the method is that it does not require development of an analytical model of the structure being tested. All predictions are made directly from the measurments taken on the structure. The efficiency of the proposed method is demonstrated using simulated data of a three-span continuous beam. The results showed that the region in which the displacement variation is maximum is the damaged region for the continuous beam. Regardless of damages being small or large, the proposed method can identify locations of structural damages accurately only using the displacement changes under the applied static load. The proposed procedure is economical for computation and simple to implement. The presented scheme may be useful for damage localization of the continuous beam.
366
Authors: Dionisio Bernal
Abstract: The Dynamic Damage Locating Vector (DDLV) technique localizes damage by interrogating changes in transfer matrices G. It is shown that although G cannot be computed in a stochastic setting a surrogate matrix whose null space is related to that of G can be extracted and this matrix suffices. The paper reviews the theoretical support for the DDLV approach, discusses the constraints used to obtain the surrogate for G, and illustrates the technique using a 12-DOF shear beam monitored with 6 sensors.
107
Authors: Ming Chih Huang, Yen Po Wang, Chien Liang Lee
Abstract: In this study, damage localization of frame structures from seismic acceleration responses is explored using the DLV technique and ARX model for system identification. The concept of the DLV method is to identify the members with zero stress under some specific loading patterns derived by interrogating the changes in flexibility matrix of the structure before and after the damage state. Success of the DLV method for damage localization lies on the ability to identify the flexibility matrix. The ARX model, a discrete-time non-parametric auto-regressive system identification technique is adopted to identify the modal parameters (natural frequencies, transfer functions and mode shapes) from which the flexibility matrices of the intact and damaged structures are constructed. To explore the effectiveness of the DLV method, a five-storey steel model frame with diagonal bracings was considered for seismic shaking table tests. The damage conditions of the structure were simulated by partially removing some of the diagonals. With the flexibility matrices of both the intact and damaged structures synthesized on a truncated modal basis, the damage locations have been successfully identified by the DLV method for either single or multiple damage conditions, regardless of the damage locations. This study confirms the potential of the DLV method in the detection of local damages from global seismic response data for frame structures.
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