Size-dependent postbuckling of annular nanoplates with different boundary conditions subjected to the axisymmetric radial loading incorporating surface stress effects

2016 ◽  
Author(s):  
R. Ansari ◽  
V. Mohammadi ◽  
M. Faghih Shojaei ◽  
R. Gholami
Keyword(s):  
Boundary Conditions ◽  
Surface Stress ◽  
Different Boundary Conditions ◽  
Stress Effects ◽  
Size Dependent ◽  
Radial Loading

Surface Stress Effect on the Pull-In Instability of Hydrostatically and Electrostatically Actuated Rectangular Nanoplates With Various Edge Supports

2012 ◽  
Vol 134 (4) ◽  
Author(s):  
R. Ansari ◽  
R. Gholami ◽  
M. Faghih Shojaei ◽  
V. Mohammadi ◽  
M. A. Darabi
Keyword(s):  
Boundary Conditions ◽  
Governing Equation ◽  
Surface Stress ◽  
Plate Thickness ◽  
Stress Effect ◽  
Residual Surface Stress ◽  
Electrostatically Actuated ◽  
Stress Effects ◽  
Size Dependent ◽  
Surface Stress Effect

This paper is aimed to investigate the size-dependent pull-in behavior of hydrostatically and electrostatically actuated rectangular nanoplates including surface stress effects based on a modified continuum model. To this end, based on the Gurtin–Murdoch theory and Hamilton's principle, the governing equation and corresponding boundary conditions of an actuated nanoplate are derived; the step-by-step linearization scheme and the differential quadrature (GDQ) method are used to discretize the governing equation and associated boundary conditions. The effects of the thickness of the nanoplate, surface elastic modulus and residual surface stress on the pull-in instability of the nanoplate are investigated. Plates made of two different materials including aluminum (Al) and silicon (Si) are selected to explain the variation of the pull-in voltage and pressure with respect to plate thickness.

Surface Stress Effects on the Yield Strength in Nanotwinned Polycrystal Face-Centered-Cubic Metallic Nanowires

2014 ◽  
Vol 81 (10) ◽  
Author(s):  
Linli Zhu ◽  
Xiang Guo ◽  
Jian Lu
Keyword(s):  
Yield Strength ◽  
Surface Stress ◽  
Mechanical Performance ◽  
Face Centered Cubic ◽  
Stress Effects ◽  
Size Dependent ◽  
The Wire ◽  
Face Centered ◽  
20 Nm ◽  
Twin Spacing

The influence of surface stress on the yield strength of nanotwinned polycrystal face-centered-cubic (FCC) metallic nanowire is theoretically investigated. The contribution of surface boundaries on the strengthening/softening is analyzed in the framework of continuum mechanics theory by accounting for the surface energy effects. The other strengthening mechanisms originated from the inner boundaries are described by the Taylor model for the nanotwinned polycrystalline metals. The theoretical results demonstrate that the yield strength of nanotwinned polycrystal wires is dependent on the twin spacing, grain size and the geometrical size of the wire. The surface stress effects on the strength perform more and more significantly with decreasing the wire diameter, especially for the diameter smaller than 20 nm. In addition, the dependence of surface stress on the strength is also relevant to the size of microstructures as well as the magnitude and direction of surface stress. These results may be useful in evaluating the size-dependent mechanical performance of nanostructured materials.

Surface Stress Effect on the Vibrational Response of Circular Nanoplates With Various Edge Supports

2013 ◽  
Vol 80 (2) ◽  
Author(s):  
R. Ansari ◽  
R. Gholami ◽  
M. Faghih Shojaei ◽  
V. Mohammadi ◽  
S. Sahmani
Keyword(s):  
Differential Equation ◽  
Boundary Conditions ◽  
Surface Stress ◽  
High Surface ◽  
Continuum Theory ◽  
Volume Ratio ◽  
Stress Effect ◽  
Size Dependent ◽  
Surface Stress Effect ◽  
Generalized Differential

The classical continuum theory cannot be directly used to describe the behavior of nanostructures because of their size-dependent attribute. Surface stress effect is one of the most important size dependencies of structures at this submicron size, which is due to the high surface to volume ratio of nanoscale domain. In the present study, the nonclassical governing differential equation together with corresponding boundary conditions are derived using Hamilton's principle, into which the surface energies are incorporated through the Gurtin-Murdoch elasticity theory. The model developed herein contains intrinsic length scales to take the size effect into account and is used to analyze the free vibration response of circular nanoplates including surface stress effect. The generalized differential quadrature (GDQ) method is employed to discretize the governing size-dependent differential equation along with simply supported and clamped boundary conditions. The classical and nonclassical frequencies of circular nanoplates with various edge supports and thicknesses are calculated and are compared to each other. It is found that the influence of surface stress can be different for various circumferential mode numbers, boundary conditions, plate thicknesses, and surface elastic constants.

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