scholarly journals Wave dispersion in fresh and hardened concrete through the prism of gradient elasticity

2016 ◽  
Vol 78-79 ◽  
pp. 149-159 ◽  
Author(s):  
Sokratis N. Iliopoulos ◽  
Dimitrios G. Aggelis ◽  
Demosthenes Polyzos
Keyword(s):  
Gradient Elasticity ◽  
Wave Dispersion ◽  
Hardened Concrete

Nonlocal Homogenization Model for Wave Dispersion and Attenuation in Elastic and Viscoelastic Periodic Layered Media

2017 ◽  
Vol 84 (3) ◽  
Author(s):  
Ruize Hu ◽  
Caglar Oskay
Keyword(s):  
Heterogeneous Media ◽  
Spatial Scales ◽  
Gradient Elasticity ◽  
Layered Media ◽  
Wave Dispersion ◽  
Momentum Balance ◽  
Eighth Order ◽  
Homogenization Model ◽  
Dispersion And Attenuation ◽  
Periodic Layered Media

This manuscript presents a new nonlocal homogenization model (NHM) for wave dispersion and attenuation in elastic and viscoelastic periodic layered media. Homogenization with multiple spatial scales based on asymptotic expansions of up to eighth order is employed to formulate the proposed nonlocal homogenization model. A momentum balance equation, nonlocal in both space and time, is formulated consistent with the gradient elasticity theory. A key contribution in this regard is that all model coefficients including high-order length-scale parameters are derived directly from microstructural material properties and geometry. The capability of the proposed model in capturing the characteristics of wave propagation in heterogeneous media is demonstrated in multiphase elastic and viscoelastic materials. The nonlocal homogenization model is shown to accurately predict wave dispersion and attenuation within the acoustic regime for both elastic and viscoelastic layered composites.

Size-dependent thermally affected wave propagation analysis in nonlocal strain gradient functionally graded nanoplates via a quasi-3D plate theory

2016 ◽  
Vol 232 (1) ◽  
pp. 162-173 ◽  
Author(s):  
Farzad Ebrahimi ◽  
Mohammad Reza Barati
Keyword(s):  
Strain Gradient ◽  
Plate Theory ◽  
Micromechanical Model ◽  
Gradient Elasticity ◽  
Wave Dispersion ◽  
Functionally Graded ◽  
Thermal Environments ◽  
Size Dependent ◽  
Dispersion Behavior ◽  
Nonlocal Strain Gradient

This article examines the application of nonlocal strain gradient elasticity theory to wave dispersion behavior of a size-dependent functionally graded nanoplate in thermal environments. The theory contains two scale parameters corresponding to nonlocal and strain gradient effects. A quasi-3D plate theory considering shear and normal deformations is employed to present the formulation. Mori–Tanaka micromechanical model is used to describe functionally graded material properties. Hamilton’s principle is employed to obtain the governing equations of nanoplate accounting for thickness stretching effect. These equations are solved analytically to find wave frequencies and phase velocities of functionally graded nanoplate. It is indicated that wave dispersion behavior of functionally graded nanoplates is significantly affected by temperature rise, nonlocality, length scale parameter, and material composition.

scholarly journals Capturing wave dispersion in heterogeneous and microstructured materials through a three-length-scale gradient elasticity formulation

2018 ◽  
Vol 27 (5-6) ◽  
Author(s):  
Dario De Domenico ◽  
Harm Askes ◽  
Elias C. Aifantis
Keyword(s):  
Gradient Elasticity ◽  
Wave Dispersion ◽  
Length Scale ◽  
Lattice Systems ◽  
Scale Parameters ◽  
Atomistic Models ◽  
Generalized Continuum ◽  
Long Range Interactions ◽  
Additional Strain ◽  
Local Lattice

AbstractLong-range interactions occurring in heterogeneous materials are responsible for the dispersive character of wave propagation. To capture these experimental phenomena without resorting to molecular and/or atomistic models, generalized continuum theories can be conveniently used. In this framework, this paper presents a three-length-scale gradient elasticity formulation whereby the standard equations of elasticity are enhanced with one additional strain gradient and two additional inertia gradients to describe wave dispersion in microstructured materials. It is well known that continualization of lattice systems with distributed microstructure leads to gradient models. Building on these insights, the proposed gradient formulation is derived by continualization of the response of a non-local lattice model with two-neighbor interactions. A similar model was previously proposed in the literature for a two-length-scale gradient formulation, but it did not include all the terms of the expansions that contributed to the response at the same order. By correcting these inconsistencies, the three-length-scale parameters can be linked to geometrical and mechanical properties of the material microstructure. Finally, the ability of the gradient formulation to simulate wave dispersion in a broad range of materials (aluminum, bismuth, nickel, concrete, mortar) is scrutinized against experimental observations.

A study on Rayleigh wave dispersion in bone according to Mindlin's Form II gradient elasticity

2014 ◽  
Vol 135 (5) ◽  
pp. 3117-3126 ◽  
Author(s):  
Maria G. Vavva ◽  
Leonidas N. Gergidis ◽  
Vasilios C. Protopappas ◽  
Antonios Charalambopoulos ◽  
Demosthenes Polyzos ◽  
...  
Keyword(s):  
Rayleigh Wave ◽  
Gradient Elasticity ◽  
Wave Dispersion ◽  
Rayleigh Wave Dispersion
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