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Showing 4 results for Wave Propagation
Damage Detection in Beam and Rod using Wave Propagation Method with Spectral Finite Elements
M. S. Eskandarjuy , A. Baghlani,
Volume 35, Issue 2 (2-2017)
Abstract

In this paper, wave propagation method was applied to detect damage of structures. Spectral Finite Element Method
(SFEM) was used to analyze wave propagation in structures. Two types of structures i.e. rod and Euler-Bernoulli beam were
modelled using spectral elements. The advantage of spectral finite element over conventional Finite Element Method (FEM), in
wave propagation problems, is its accuracy and lower computational time. Two examples of rod and Euler-Bernoulli beam with
embeded concentrated mass were presented to illustrate the superiority of SFEM to FEM. Finally, a cracked beam was modeled
and analyzed using spectral finite elements and the location of the crack was determined using time history response of beam
structure.


Simulation of Elastic Wave Propagation through Steel/Epoxy Phononic Crystal Waveguide by Displacement-Based Finite Difference Method
M. Moradi, M. Bagheri Nouri,
Volume 36, Issue 1 (9-2017)
Abstract
In order to obtain transmission spectra through a phononic crystal as well as its waveguide, a new algorithm is presented in this paper. By extracting displacement-based forms of elastic wave equations and their discretization, Displacement- Based Finite Difference Time Domain (DBFDTD) algorithm is presented. Two numerical examples are solvcd with this method and the results are compared with the conventional Finite Difference Time Domain (FDTD) method. In addition, the computational cost of the new approach has been compared with the conventional FDTD method. This comparison showed that the computation time of the DBFDTD method is 40 percent less than that of the conventional FDTD method.

Investigation of Piezoelectric Coupling and Anisotropy Effect on Acoustic Wave Propagation at LithiumNiobate Crystalloacoustic
Sh Rezaei, M Eskandari-Ghadi, M. Rahimian,
Volume 36, Issue 1 (9-2017)
Abstract
The acoustic wave velocity depends on elasticity and density at most materials, but because of anisotropy and especially piezoelectric coupling effect, the acoustic wave propagation at piezoelectric based crystalloacoustic materials, is an applied and challenging problem. In this paper, using modified Christoffel's equation based on group velocity concept, the effect of anisotropy and piezoelectric coupling at different wafers of lithium niobate crystalloacoustic (strong anisotropy) on acoustic wave velocity (semi-longitudinal, semi-vertical transverse wave and semi-horizontal transverse wave) is investigated, and validated by experimental data. Then, the acoustic wave velocity ranges that can be supported are determined. The result of this study can be essential at acoustic metamaterials design, Phononic crystal and piezoelectric based wave-guides.

Modelling Wave Propagation in Thin Plates with the pectral Modal Method
F. Shirmohammadi, M. M. Saadatpour,
Volume 37, Issue 1 (9-2018)
Abstract
In this article spectral modal method is developed for studying wave propagation in thin plates with constant or variable thickness. Theses plates are subjected to the impact forces and different boundary conditions. Spectral modal method can be considered as the combination of Dynamic Stiffness Method (DSM), Fourier Analysis Method (FAM) and Finite Stripe Method (FSM). Using modeling of continuous distribution of mass and an exact stiffness causes solutions in frequency domain. Unlike the most numerical methods, in this method refining meshes is no longer necessary in which the cost and computational time is decreased. In this paper the important parameters of the method and their effects on results are studied through different examples.

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