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A mode conversion-based algorithm for detecting rectangular notch parameters in plates using Lamb waves
, Article Archive of Applied Mechanics ; Volume 85, Issue 6 , 2015 , Pages 793-804 ; 09391533 (ISSN) ; Behzad, M ; Mirdamadi, H. R ; Sharif University of Technology
Springer Verlag
2015
Abstract
In this paper, an algorithm for identifying rectangular notch parameters as damage in a plate using Lamb waves is presented. In this algorithm, a combination of pulse-echo and pitch-catch methods is used. The method is divided into two steps: notch localization and notch geometry detection. The bases for this algorithm are mode conversion and scattering phenomena because of interaction of Lamb wave modes with defects. The method is applied to some numerical examples, and the results show that it can successfully identify all of rectangular notch parameters, i.e., its location, depth, and width
Damage identification in multi-step waveguides using Lamb waves and scattering coefficients
, Article Archive of Applied Mechanics ; Volume 88, Issue 6 , June , 2018 , Pages 1009-1026 ; 09391533 (ISSN) ; Behzad, M ; Mirdamadi, H. R ; Sharif University of Technology
Springer Verlag
2018
Abstract
Damage detection in uniform structures has been studied in numerous previous researches. However, damage detection in non-uniform structures is less studied. In this paper, a damage detection algorithm for identifying rectangular notch parameters in a stepped waveguide using Lamb waves is presented. The proposed algorithm is based on mode conversion and scattering phenomena because of interaction of Lamb wave modes with defects. The analysis is divided into two steps: notch localization and notch geometry detection. The main advantage of this method is its ability to detect all of the notch parameters in a waveguide with arbitrary number of step discontinuities. The method is applied to a...
Structural Health Monitoring of Beam with Symmetric Discontinuity Using Ultrasonic Guided Wave Propagation
, M.Sc. Thesis Sharif University of Technology ; Behzad, Mehdi (Supervisor) ; Mirdamadi, Hamid Reza (Co-Advisor)
Abstract
Damage identification in uniform structures using Lamb waves has been studied by the researchers; however, as most of the industrial structures are not uniform, it is necessary to study more complex structures. In this thesis, a method of identifying notch specifications as damage in a symmetric stepped beam with arbitrary number of steps using Lamb wave propagation is presented. Initially, the study will examine and compare the Lamb wave propagation in uniform, symmetric stepped and asymmetric stepped beams. In the first stage, a method for detection of damage location in symmetric stepped beam is presented. This method is based on mode conversion phenomenon of Lamb wave modes. Moreover,...
Nonlinear interaction of intense hypergeometric Gaussian subfamily laser beams in plasma
, Article Optics and Laser Technology ; Volume 81 , 2016 , Pages 40-45 ; 00303992 (ISSN) ; Vaziri, M. (Khamedi) ; Rooholamininejad, H ; Bahrampour, A. R ; Sharif University of Technology
Elsevier Ltd
Abstract
Propagation of Hypergeometric-Gaussian laser beam in a nonlinear plasma medium is investigated by considering the Source Dependent Expansion method. A subfamily of Hypergeometric-Gaussian beams with a non-negative, even and integer radial index, can be expressed as the linear superposition of finite number of Laguerre-Gaussian functions. Propagation of Hypergeometric-Gaussian beams in a nonlinear plasma medium depends on the value of radial index. The bright rings' number of these beams is changed during the propagation in plasma medium. The effect of beam vortex charge number l and initial (input) beam intensity on the self-focusing of Hypergeometric-Gaussian beams is explored. Also, by...