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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 >

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1136

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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 >

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968

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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 >

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978

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ARTICLE

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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