Open Access

ARTICLE

Dennis Bäcker¹, Andreas Ricoeur², Meinhard Kuna¹
Structural Durability & Health Monitoring, Vol.7, No.1&2, pp. 1-22, 2011, DOI:10.3970/sdhm.2011.007.001
Abstract A new sensor concept for monitoring fatigue crack growth in technical structures is presented. It allows the in-situ determination of the position of the crack tip as well as the fracture mechanical quantities. The required data are obtained from a piezoelectric polymer film, which is attached to the surface of the monitored structure. The stress intensity factors and the crack tip position are calculated from electrical potentials obtained from a sensor array by solving the non-linear inverse problem. More >

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1022

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ARTICLE

Gouravaraju Saipraneeth¹, Ranjan Ganguli²
Structural Durability & Health Monitoring, Vol.7, No.1&2, pp. 23-64, 2011, DOI:10.3970/sdhm.2011.007.023
Abstract In this paper, the effect of damage on mode shape related parameters of a beam is investigated. The damage is represented by a localized reduction in beam stiffness. The damage location and amount is varied using a finite element model of the beam to obtain the mode shapes. A beam which is simply supported at both ends is used for the numerical results. The periodic nature of the beam is exploited to obtain spatial Fourier coefficients of the mode shapes. As the damage location and size are varied, it is found that the Fourier coefficients also change and are found… More >

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1081

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926

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ARTICLE

Clyde K Coelho, Cristobal Hiche, Aditi Chattopadhyay
Structural Durability & Health Monitoring, Vol.7, No.1&2, pp. 65-82, 2011, DOI:10.3970/sdhm.2011.007.065
Abstract Low velocity impacts on composite plates often create subsurface damage that is difficult to diagnose. Fiber Bragg grating (FBG) sensors can be used to detect subsurface damage in composite laminates due to low velocity impact. This paper focuses on the prediction of impact loading in composite structures as a function of time using a support vector regression approach. A time delay embedding feature extraction scheme is used since it can characterize the dynamics of the impact using the sensor signals. The novelty of this approach is that it can be applied on complex geometries and does not require a dense… More >

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913

Open Access

ARTICLE

C. Braccesi¹, F. Cianetti^1,2
Structural Durability & Health Monitoring, Vol.7, No.1&2, pp. 83-118, 2011, DOI:10.3970/sdhm.2011.007.083
Abstract In this paper the problem of the correct evaluation of the stress state of mechanical components of non linear systems in the frequency domain was analysed. This is one of the most important steps in the frequency domain evaluation of the fatigue behaviour of components submitted to random loads. A new methodology to obtain an accurate representation in frequency domain of the non-linear behaviour of the system as well as of the stress state of the components both in terms of power spectral density (PSD) function and of frequency response function (FRF) was proposed and validated. This methodology is useful… More >

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1211

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ARTICLE

P. Gayathri¹, R. Ganguli^1,2
Structural Durability & Health Monitoring, Vol.7, No.1&2, pp. 119-138, 2011, DOI:10.3970/sdhm.2011.007.119
Abstract The effect of random variation in composite material properties on the reliability of structural damage detection is addressed in this paper. A composite plate is considered as the structure and a finite element model is used for the simulation. Damage growth due to cyclic loading is addressed. Matrix crack induced delamination is emphasized in this paper. Thresholds for the damage accumulation are found using finite element simulations so that the structure can be subjected to inspections and removed from service safely. Uncertainty effects of composite material properties on the response of the structure are quantified using Monte Carlo simulations. Vibration… More >

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867

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ARTICLE

Ramamurty Raju P.¹, Rajesh S.¹, Satyanarayana B.², Ramji K.³
Structural Durability & Health Monitoring, Vol.7, No.1&2, pp. 139-152, 2011, DOI:10.3970/sdhm.2011.007.139
Abstract This paper presents the details of method of sample size determination to estimate the characteristic fatigue life of aluminum alloy, A356.2-T6. The characteristic fatigue life of the alloy has been estimated by assuming log normal distribution model. A step wise procedure is outlined to determine the number of specimens required at predetermined stress amplitude to estimate the fatigue life with an acceptable error at 50% probability and various confidence levels, 90%, 95% and 99%. Maximum percentage of errors has also been calculated for the above probability and confidence levels. Details of generation of S-N curve for aluminum alloy A356.2-T6 using… More >

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1692