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Propagation of SH Wave in Elastic Media with Cylindrical Inhomogeneity at Micro and Nano Scales by Couple Stress Theory
, M.Sc. Thesis Sharif University of Technology ; Mohammadi Shodja, Hossein (Supervisor)
Abstract
It is well known that the classical continuum theory does not consider size effect in predicting material’s behavior, however at the micro and nano scales, this effect is not negligible and the classical theory has deficiencies at these scales. To take into account the size effect, higher order continuum theories introduce new material constants into the formulation. One famous version of these theories is couple stress which is applied in this research. This theory considers size effect of inhomogeneity by employing Characteristic length of materials. Quasi-static couple stress and classical dynamic approaches do not include explicitly the size of the material unit cell in the formulation...
The electro-elastic scattered fields of an SH-wave by an eccentric two-phase circular piezoelectric sensor in an unbounded piezoelectric medium
, Article Mechanics of Materials ; Vol. 75 , 2014 , pp. 1-12 ; ISSN: 01676636 ; Jarfi, H ; Rashidinejad, E ; Sharif University of Technology
Abstract
The dynamic equivalent inclusion method (DEIM) which was first proposed by Fu and Mura (1983), in its original context has some shortcomings, which were pointed out and remedied by Shodja and Delfani (2009) who introduced the new consistency conditions along with the related micromechanically substantiated notion of eigenstress and eigenbody-force fields. However, these theories are bound to elastic media with isotropic phases. The present work extends the idea of the above-mentioned new DEIM to the dynamic electro-mechanical equivalent inclusion method (DEMEIM) for the treatment of the scattering of SH-waves by a two-phase circular piezoelectric obstacle bonded to a third phase...
Determination of the scattered fields of an SH-wave by an eccentric coating-fiber ensemble using DEIM
, Article International Journal of Engineering Science ; Volume 46, Issue 11 , 2008 , Pages 1136-1146 ; 00207225 (ISSN) ; Mohammadi Shodja, H ; Delfani, M. R ; Sharif University of Technology
2008
Abstract
To date, the existing theories pertinent to the determination of the scattered fields of an inhomogeneity have been limited to certain topological symmetries for which the method of wave-function expansion is widely used. In the literature the wave-function expansion method has also been employed to the case involving concentric coated fiber. An alternative approach is the dynamic equivalent inclusion method (DEIM) proposed by Fu and Mura [L.S. Fu, T. Mura, The determination of elastodynamic fields of an ellipsoidal inhomogeneity. ASME J. Appl. Mech. 50 (1983) 390-396.] who found the scattered field of a single spheroidal inhomogeneity. The pioneering work of Eshelby [J.D. Eshelby, The...
Wave propagation in a three-dimensional half-space with semi-infinite irregularities
, Article Waves in Random and Complex Media ; 2021 ; 17455030 (ISSN) ; Sotoudeh, P ; Ghaemian, M ; Sharif University of Technology
Taylor and Francis Ltd
2021
Abstract
Dynamic analysis of problems with complex geometries requires utilization of numerical methods. To completely capture the effects of seismic wave propagation in a system, one must consider the structure or irregularity within its encompassing half-space. Correct consideration of half-space in a numerical model is important specially when it comes to cases where the half-space contains semi-infinite irregularities. In this study, a generalized numerical methodology is presented for dynamic analysis of a half-space with semi-infinite irregularities. The methodology is first verified through comparison with analytical solution of known problems. Then the method is employed to solve the dynamic...
Scattering of SH-Waves by a Cylindrical Multi Inhomogeneity Embedded in a Piezo-Electromagnetic Medium Using an Analytical Innovative Micromechanical Approach
, Ph.D. Dissertation Sharif University of Technology ; Mohammadi Shodja, Hossein (Supervisor)
Abstract
This work examines the problem of the fully coupled magneto-electro-elastic (MEE) scattering of SH-waves incident upon a heterogeneous MEE scatterer which is embedded in an unbounded medium. The scatterer consists of a circular core and a circular encapsulator with eccentricity. All three regions: the core, encapsulator, and the surrounding matrix have distinct MEE properties and fully coupled constitutive relations. The generated coupled MEE fields coexist simultaneously in all these regions without resort to any simplifying assumptions. The precise description of the multifunctionality involves the solution of three fully coupled partial differential equations in three different regions....
Scattering of SH-waves by an elliptic cavity/crack beneath the interface between functionally graded and homogeneous half-spaces via multipole expansion method
, Article Journal of Sound and Vibration ; Volume 435 , 2018 , Pages 372-389 ; 0022460X (ISSN) ; Shodja, H. M ; Sharif University of Technology
Academic Press
2018
Abstract
In this study, based on multipole expansion method an analytical treatment is presented for the anti-plane scattering of SH-waves by an arbitrarily oriented elliptic cavity/crack which is embedded near the interface between exponentially graded and homogeneous half-spaces. The cavity is embedded within the inhomogeneous half-space. The boundary value problem of interest is solved by constructing an appropriate set of multipole functions which satisfy (i) the governing equation in each half-space, (ii) the continuity conditions across the interface between the two half-spaces, and (iii) the far-field radiation and regularity conditions. The analytical expressions for the scattered...
Interface effects on the electromagnetic radiation emanating from an embedded piezoelectric nano-fiber incident upon by SH-waves
, Article Wave Motion ; Volume 94 , April , 2020 ; Shodja, H. M ; Sharif University of Technology
Elsevier B.V
2020
Abstract
The multiphysics process of the electromagnetic (EM) radiation induced from an embedded nanofiber scatterer subjected to SH-waves is of interest. By discarding the commonly employed electroquasistatic approximation, the fully-coupled elastodynamics and Maxwell's equations have been solved simultaneously within the mathematical framework of piezoelectric surface elasticity theory. Certain subtleties regarding the introduced interface characteristic lengths that make the examination of the size effect on the EM radiated power, scattering cross section, fundamental resonance frequency, and distribution of the magnetic field possible will be discussed. The obtained results can be helpful for...
Band-structure calculation of SH-waves in 1D hypersonic nano-sized phononic crystals with deformable interfaces
, Article Mechanics of Materials ; Volume 171 , 2022 ; 01676636 (ISSN) ; Shodja, H. M ; Sanati, M ; Sharif University of Technology
Elsevier B.V
2022
Abstract
Nanoscopic interface deformations between the layers in a superlattice have a great impact on its phononic band-structure. This work aims to study the SH-wave band-structure in one-dimensional (1D) multilayer hypersonic nano-sized phononic crystals with consideration of local deformations at the interfaces of the layers. At this scale, the traditional theory of elasticity is unable to capture the realistic forbidden and permitted frequencies. Thus, in light of surface/interface elastodynamics theory for nanostructures with deformable interfaces, a mixed variational method which accounts for the notion of interface elasticity, deformability, and inertia is introduced in the present work. For...
Three-dimensional nonlinear seismic analysis of concrete faced rockfill dams subjected to scattered P, SV, and SH waves considering the dam-foundation interaction effects
, Article Soil Dynamics and Earthquake Engineering ; Volume 31, Issue 5-6 , 2011 , Pages 792-804 ; 02677261 (ISSN) ; Mohsen Haeri, S ; Karimi, M ; Sharif University of Technology
2011
Abstract
In this study, the nonlinear seismic analysis of a typical three-dimensional concrete faced rockfill dam is reported. Three components of the Loma Prieta (Gilroy 1 station) earthquake acceleration time history are used as input excitation. The dam under study is considered as if it were located in a prismatic canyon with a trapezoidal cross-section. A nonlinear model for the rockfill material is used, and contact elements with Coulomb friction law are utilized at the slab-rockfill interface. Vertical joints in the face slab are also considered in the finite element model. A substructure method, in which the unbounded soil is modelled by the scaled boundary finite element method (SBFEM), is...