Home / Journals / SDHM / Vol.5, No.1, 2009
  • 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

    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

    An Automated Procedure for the Geometrical Modelling of a Surface Crack Front

    J. Toribio1, J.C. Matos2, B. González1, J. Escuadra2
    Structural Durability & Health Monitoring, Vol.5, No.1, pp. 57-72, 2009, DOI:10.3970/sdhm.2009.005.057
    Abstract In this paper an automatic (analytical-numerical) procedure is proposed to model the front of a transverse surface crack located in the circular section of a lineal structural element (wire, cable, strand, rod, shaft,..., i.e., a cylindrical geometry) by means of a fitting ellipse, obtaining the ellipse parameters from a series of points in therealcrack front and adjusting them to thetheoreticalfitting ellipse by a least square method. For symmetric cracks two modelling procedures are formulated: (i) in the first one, a fitting ellipse is used wit its centre belonging to the periphery of the circular section of the cylinder; (ii) in… More >

  • Open Access

    ARTICLE

    An Evaluation of Fatigue Crack Growth in a Reactor Steel in Air and Aqueous Environments Considering Closure Effects

    Ivo Černý1, Václav Linhart2
    Structural Durability & Health Monitoring, Vol.5, No.1, pp. 73-86, 2009, DOI:10.3970/sdhm.2009.005.073
    Abstract The experimental programme described in the paper was aimed at an evaluation of fatigue crack growth (FCG) rate and threshold conditions in a reactor pressure vessel steel in laboratory air and in simple aqueous environment. Though the main target of the work was to enlarge the data basis for possible future needs of defect and risk assessment, an emphasis was put on an evaluation of crack growth mechanisms. It was shown that despite some recent works infirming crack closure phenomenon itself or methods of its evaluation, crack closure explained near-threshold fatigue crack behaviour in the specific case of the reactor… More >

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