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.

Nonlinear semi-analytical nonlocal strain-gradient dynamic response investigation of phase-transition-induced transversely graded hierarchical viscoelastic nano/microplates

2019 ◽  
Vol 233 (15) ◽  
pp. 5388-5409 ◽  
Author(s):  
M Shariyat ◽  
F Farrokhi
Keyword(s):  
Strain Gradient ◽  
Viscoelastic Model ◽  
Functionally Graded ◽  
Special Technique ◽  
Stress And Strain ◽  
Transient Vibration ◽  
Size Dependent ◽  
Integration Schemes ◽  
Series Type ◽  
Nonlocal Strain Gradient

A functionally graded Boltzmann hierarchical viscoelastic model with both stress- and strain-gradient nonlocalities is developed and implemented to extract results that are more precise than results of Eringen's nonlocal elasticity model. The available size-dependent vibration analyses of the nano/microplates have focused on the frequency analysis and even not the time-dependent transient vibration analyses. In the present research, the forced and transient responses of the microplates are studied comprehensively, for the first time, using a three-element standard solid viscoelastic model. The studied transversely symmetric graded viscoelastic microplate and the relevant function of the material properties variations contain notable hints as well. Furthermore, the resulting new sixth-order nonlocal strain gradient integrodifferential equations are solved by a special technique that includes an analytical spatial Navier series-type solution and a trapezoidal and Runge–Kutta integration schemes, in time domain. Finally, the influences of the stress- and strain-gradient nonlocality parameters and the viscoelasticity parameters on the dynamic behaviors of the viscoelastic FGM microplates are investigated in details. Results show that the effects of the strain gradient nonlocality on the viscodynamic results may be much remarkable than those of the length scale nonlocality, in microscales.

Nonlocal stress-strain gradient vibration analysis of heterogeneous double-layered plates under hygro-thermal and linearly varying in-plane loads

2017 ◽  
Vol 24 (19) ◽  
pp. 4630-4647 ◽  
Author(s):  
Mohammad Reza Barati
Keyword(s):  
Strain Gradient ◽  
Vibration Analysis ◽  
Plate Theory ◽  
Nonlocal Parameter ◽  
Load Factor ◽  
Governing Equations ◽  
Layered Plates ◽  
Accurate Analysis ◽  
Thermal Environments ◽  
Nonlocal Strain Gradient

This paper develops a nonlocal strain gradient plate model for vibration analysis of double-layered graded nanoplates under linearly variable in-plane mechanical loads in hygro-thermal environments. For more accurate analysis of nanoplates, the proposed theory contains two scale parameters related to the nonlocal and strain gradient effects. The double-layered nanoplate is modeled via a four-variable shear deformation plate theory needless of shear correction factors. Governing equations of a nonlocal strain gradient nanoplate on elastic substrate are derived via Hamilton’s principle. Galerkin’s method is implemented to solve the governing equations. Effects of different factors such as in-plane loading, load factor, nonlocal parameter, length scale parameter, moisture percentage rise, temperature rise, elastic foundation, and boundary conditions on vibration characteristics of a double-layered nanoplate have been examined.

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