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  • Open Access

    ARTICLE

    Structures with Surface-Bonded PZT Piezoelectric Patches: a BEM Investigation into the Strain-transfer Mechanism for SHM applications

    I. Benedetti1, A. Milazzo1, M.H. Aliabadi2

    Structural Durability & Health Monitoring, Vol.5, No.3, pp. 251-274, 2009, DOI:10.3970/sdhm.2009.005.251

    Abstract In this work a three-dimensional BEM model is used for the analysis of structures with cracks and surface bonded piezoelectric PZT patches used as strain sensors. The cracked structure is modelled by the dual boundary element method, which allows for accurate and reliable crack analysis, while the piezoelectric patch is analyzed by a finite element state-space approach, that embodies both the full electro-mechanical coupling and the suitable sensor's boundary conditions. The model is used to investigate the strain-transfer mechanism from an host elastic structure to the piezoelectric layer, taking into account the effect of the adhesive layer, as well as… More >

  • Open Access

    ARTICLE

    Unsupervised Time-series Fatigue Damage State Estimation of Complex Structure Using Ultrasound Based Narrowband and Broadband Active Sensing

    S.Mohanty1, A. Chattopadhyay2, J. Wei3, P. Peralta4

    Structural Durability & Health Monitoring, Vol.5, No.3, pp. 227-250, 2009, DOI:10.3970/sdhm.2009.005.227

    Abstract This paper proposes unsupervised system identification based methods to estimate time-series fatigue damage states in real-time. Ultrasound broadband input is used for active damage interrogation. Novel damage index estimation techniques based on dual sensor signals are proposed. The dual sensor configuration is used to remove electrical noise, as well as to improve spatial resolution in damage state estimation. The scalar damage index at any particular damage condition is evaluated using nonparametric system identification techniques, which includes an empirical transfer function estimation approach and a correlation analysis approach. In addition, the effectiveness of two sensor configurations (configuration 1: sensors placed near… More >

  • Open Access

    ARTICLE

    Real Time Damage State Estimation and Condition Based Residual Useful Life Estimation of a Metallic Specimen under Biaxial Loading

    S.Mohanty1, A. Chattopadhyay2, J. Wei3, P. Peralta4

    Structural Durability & Health Monitoring, Vol.5, No.1, pp. 33-56, 2009, DOI:10.3970/sdhm.2009.005.033

    Abstract The current state of the art in the area of real time structural health monitoring techniques offers adaptive damage state prediction and residual useful life assessment. The present paper discusses the use of an integrated prognosis model, which combines an on-line state estimation model with an off-line predictive model to adaptively estimate the residual useful life of an Al-6061 cruciform specimen under biaxial loading. The overall fatigue process is assumed to be a slow time scale process compared to the time scale at which, the sensor signals were acquired for on-line state estimation. The on-line state estimation model was based… More >

  • Open Access

    ARTICLE

    Frequency Domain based Damage Index for Structural Health Monitoring

    G. Giridhara1, S. Gopalakrishnan2

    Structural Durability & Health Monitoring, Vol.5, No.1, pp. 1-32, 2009, DOI:10.3970/sdhm.2009.005.001

    Abstract In this paper, a new damage measure in the frequency domain (FDI), which uses the definition of strain energy in the frequency domain, is proposed. The proposed damage index is derived using the definition of frequency domain strain energy. The base line responses and the strain energies are computed using Wavelet Spectral Finite elements, while the strain energies for the damaged structure is computed using four high fidelity experimental responses. The sensitivity of the damage measure in locating cracks of different sizes and orientation is demonstrated on a square plate, the rectangular plate and on a compressor blade. More >

  • Open Access

    ARTICLE

    Sensitivity of Eigen Value to Damage and Its Identification

    B.K.Raghuprasad1, N.Lakshmanan2, N.Gopalakrishnan2, K.Muthumani2

    Structural Durability & Health Monitoring, Vol.4, No.3, pp. 117-144, 2008, DOI:10.3970/sdhm.2008.004.117

    Abstract The reduction in natural frequencies, however small, of a civil engineering structure, is the first and the easiest method of estimating its impending damage. As a first level screening for health-monitoring, information on the frequency reduction of a few fundamental modes can be used to estimate the positions and the magnitude of damage in a smeared fashion. The paper presents the Eigen value sensitivity equations, derived from first-order perturbation technique, for typical infra-structural systems like a simply supported bridge girder, modelled as a beam, an end-bearing pile, modelled as an axial rod and a simply supported plate as a continuum… More >

  • Open Access

    ARTICLE

    Electromechanical Admittance -- Based Damage Identification Using Box-Behnken Design of Experiments

    C.P. Providakis1, M.E. Voutetaki

    Structural Durability & Health Monitoring, Vol.3, No.4, pp. 211-228, 2007, DOI:10.3970/sdhm.2007.003.211

    Abstract Piezoceramic transducers have emerged as new tools for the health monitoring of large-scale structures due to their advantages of active sensing, low cost, quick response, availability in different shapes, and simplicity for implementations. In the present paper, a statistical metamodeling utilization of electro-mechanical (E/M) admittance approach by applying piezoelectric materials to the damage identification is investigated. A response surface metamodel is constructed by empirically fitting a model to a set of design points chosen using a Box-Behnken design of experiment (simulation) technique. This empirical fit allows polynomial models to be produced for relating damage parameter such that stiffness reduction to… More >

  • Open Access

    ARTICLE

    An Investigation into Active Strain Transfer Analysis in a Piezoceramic Sensor System for Structural Health Monitoring Using the Dual Boundary Element Method

    S.P.L. Leme1, M.H. Aliabadi2, L.M. Bezerra1, P.W. Partridge1

    Structural Durability & Health Monitoring, Vol.3, No.3, pp. 121-132, 2007, DOI:10.3970/sdhm.2007.003.121

    Abstract The coupled electromechanical behaviour of a thin piezoceramic sensor bonded to a stiffened panel subjected to membrane mechanical loadings is examined. The sensor is characterised by an electrostatic line model bonded to a damaged panel modelled by the dual boundary element method. Numerical results obtained demonstrate that the proposed method is capable of modelling changes in the signal output due to presence of cracks. Also presented is a numerical model for detecting fatigue crack growth in a stiffened panel using piezoceramic sensors. More >

  • Open Access

    ABSTRACT

    A Vision-based Displacement Measurement Method for Structural Health Monitoring of Large-scale Infrastructures

    Hyung-Jo Jung, Jong-Jae Lee, Jeong-Su Park

    The International Conference on Computational & Experimental Engineering and Sciences, Vol.19, No.4, pp. 125-126, 2011, DOI:10.3970/icces.2011.019.125

    Abstract A vision-based displacement measurement method for structural health monitoring of large-scale infrastructures such as high-rise buildings and long-span bridges is presented. The method uses digital image processing techniques including a target recognition algorithm, projection of the captured image, and calculation of the actual displacement using target geometry and the number of pixels moved. To measure the displacement of a flexible structure from a distant location which can be regarded as a fixed reference point, a novel image processing method has been devised by means of successive estimation of relative displacement and rotational angle using a synchronized vision-based system. By measuring… More >

  • Open Access

    ABSTRACT

    Stay cable vehicle live load effects analysis based on structural health monitoring data

    C.M. Lan1, H. Li1

    The International Conference on Computational & Experimental Engineering and Sciences, Vol.12, No.3, pp. 75-82, 2009, DOI:10.3970/icces.2009.012.075

    Abstract Stay cables are some of the most critical structural components of a bridge. However, stay cables readily suffer from corrosion damage and stress corrosion damage. Thus, health monitoring of stay cables is important for ensuring the integrity and safety of a bridge. Glass Fibre Reinforced Polymer Optical Fibre Bragg Grating (GFRP-OFBG) cable, a kind of fibre Bragg grating optical sensing technology-based smart stay cables, is proposed in this study. The fabrication procedure of the smart stay cable was developed and the self-sensing property of the smart stay cable was calibrated. The application of the smart stay cables on the Tianjin… More >

  • Open Access

    ABSTRACT

    Unsupervised Support Vector Machine Based Principal Component Analysis for Structural Health Monitoring

    Chang Kook Oh1, Hoon Sohn1

    The International Conference on Computational & Experimental Engineering and Sciences, Vol.8, No.3, pp. 91-100, 2008, DOI:10.3970/icces.2008.008.091

    Abstract Structural Health Monitoring (SHM) is concerned with identifying damage based on measurements obtained from structures being monitored. For the civil structures exposed to time-varying environmental and operational conditions, it is inevitable that environmental and operational variability produces an adverse effect on the dynamic behaviors of the structures. Since the signals are measured under the influence of these varying conditions, normalizing the data to distinguish the effects of damage from those caused by the environmental and operational variations is important in order to achieve successful structural health monitoring goals. In this paper, kernel principal component analysis (kernel PCA) using unsupervised support… More >

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