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FE-PML Modeling of Guided Elastic Waves and its Applications to Ultrasonic NDE

Posted on:2011-08-17Degree:Ph.DType:Thesis
University:University of Manitoba (Canada)Candidate:Mahmoud, Abdel-RahmanFull Text:PDF
GTID:2442390002955043Subject:Applied mechanics
Abstract/Summary:
This thesis investigates the use of a combined finite element and perfectly matched layer approach in modeling guided elastic wave motion in infinite plates and cylinders and its potential applications to non-destructive evaluation. Underlying principles of the perfectly-matched, absorbing layer are demonstrated on one-dimensional wave propagation in a semi-infinite elastic rod.;Time-domain, finite-element formulation of the perfectly matched layer for pressure, shear-vertical wave motion was validated through comparisons with semi-analytical literature data and reciprocity checks. Numerical implementation of the model was employed in studying the effect of crack presence on the time of arrival in a pitch-catch, non-destructive inspection arrangement. Predictions made confirmed previously-reported experimental findings.;Extensions into three-dimensional, Cartesian and cylindrical spaces were validated against reported data. Practical examples of wave scattering in damaged concrete beams, oil and gas pipelines, and composite shells demonstrated the potential use of the proposed model in simulating elastic-wave based non-destructive inspection. Up to 80% of the computational time needed to run an extended-mesh, finite-element model can be saved by introducing the perfectly-matched, absorbing layer to the finite-element model as the current thesis proposes. This significant saving in computational time by the proposed FE-PML model can accelerate the production of artificial neural network training data or help tackle complicated non-destructive testing applications.;Feasibility of using the perfectly matched layer as absorbing boundary condition in the finite-element modeling of guided elastic wave propagation and scattering is studied for the canonical problem of shear horizontal wave motion in isotropic plates. Numerical results in this study are validated against exact analytical solutions. Excellent agreement has motivated the endeavour to take the technique to the next level of pressure, shearvertical wave motion in isotropic and transversely isotropic plates.
Keywords/Search Tags:Wave, Guided elastic, Model, Perfectly matched layer, Applications
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