Determination of stress intensity factors and J-integrals using the method of caustics

Lee, Ouk Sub; Hong, Seong Kyeong

doi:10.1016/0013-7944(93)90118-c

Cited by 10 publications

(1 citation statement)

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“…Apart from development of various techniques, another important direction in experimental determination of static stress intensity factors is the application of the existing techniques to corroborate the analytical/numerical solutions of the SIFs. For example, application of photoelastic methods is dealt in [Marloff et al 1971;Chan and Chow 1979;Kazemi et al 1989;Nurse et al 1994] and caustics techniques in [Baik et al 1995;Lee and Hong 1993]. Such investigations establish the existing techniques as useful tools in real design situations of great complexity.…”

Section: Discussionmentioning

confidence: 99%

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2008

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This paper introduces a wave propagation-based damage index which relies on the evaluation of the strain energy distribution associated with propagating waves. The presence of localized damages typically distorts the wavefield by causing reflections and diffractions. The evaluation of such distortions, in reference to the wavefield corresponding to the undamaged structure, can be used as an indicator which potentially locates, quantifies and classifies the damage.The damage index formulation is first illustrated through a numerical model of a beam with a small notch, modeled as a localized thickness reduction. The beam's wave propagation response is simulated through the combined application of perturbation techniques and the spectral finite element method. The perturbation approach and a first order model for the beam capture the coupling between bending and axial behavior caused by the damage, and allow the prediction of mode conversion phenomena. The perturbation solution allows direct comparison between undamaged and damaged strain energy contributions, which are directly associated with perturbation solutions of different orders. The resulting damage index locates the damage along the beam length and estimates its severity.Experimentally, the damage index is implemented by considering full wavefield measurements obtained through a scanning laser vibrometer. The undamaged reference response is derived directly from measurements on the damaged component, through the application of a filtering procedure operating in the wavenumber/frequency domain.

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