Investigation of the vibration and buckling of graphynes: A molecular dynamics-based finite element model

2016 ◽  
Vol 231 (6) ◽  
pp. 1162-1178 ◽  
Author(s):  
Saeed Rouhi ◽  
Tayyeb Pour Reza ◽  
Babak Ramzani ◽  
Saeed Mehran
Keyword(s):  
Molecular Dynamics ◽  
Finite Element ◽  
Aspect Ratio ◽  
Boundary Conditions ◽  
Finite Element Model ◽  
Molecular Dynamics Simulations ◽  
Element Model ◽  
Side Length ◽  
Aspect Ratios ◽  
Dynamics Simulations

Molecular dynamics simulations are used to investigate the mechanical properties of graphynes. To study the effect of atomic structure and graphyne size on Young’s and bulk modulus, armchair and zigzag nanosheets with different side lengths and aspect ratios are considered. It is observed that at a constant aspect ratio (the ratio of height to side length), variation of side length has no significant effect on Young’s modulus of graphynes. Besides, using the obtained results by molecular dynamics simulations, a finite element model is proposed to study the vibrational and buckling behaviors of graphynes. The effects of different parameters such as nanosheet geometry and boundary conditions on the fundamental natural frequency and critical buckling force of graphynes are explored. It is shown that increasing side length has an inverse effect on the frequency and buckling force. Increasing aspect ratio results in decreasing the frequency. However, this effect reduces for longer sheets. Increasing aspect ratio results in converging the vibration curves associated with graphynes under different boundary conditions. Moreover, by increasing aspect ratio, the sensitivity of buckling force to aspect ratio variation decreases.

Vibrational analysis of single-layered silicon carbide nanosheets and single-walled silicon carbide nanotubes using nanoscale finite element method

2016 ◽  
Vol 231 (18) ◽  
pp. 3455-3461 ◽  
Author(s):  
R Ansari ◽  
S Rouhi
Keyword(s):  
Molecular Dynamics ◽  
Silicon Carbide ◽  
Finite Element ◽  
Finite Element Model ◽  
Molecular Dynamics Simulations ◽  
Three Dimensional ◽  
Vibrational Analysis ◽  
Element Model ◽  
Vibrational Behavior ◽  
Dynamics Simulations

A three-dimensional finite element model has been used here to study the vibrational behavior of silicon carbide nanosheets and nanotubes. The bonds of hexagonal lattices of SiC nanosheets have been modeled by structural beam elements, and at the corners, mass elements are placed instead of Si and C atoms. Moreover, molecular dynamics simulations are performed to verify the finite element model. Comparing the results of finite element model and molecular dynamics simulations, it is concluded that the utilized approach can predict the results of molecular dynamics simulations with a reasonable accuracy. It is observed that the atomic structure does not significantly affect the vibrational behavior of nanosheets. Besides, increasing the size of nanosheet results in decreasing the effect of geometry variation. As the aspect ratio of nanotubes increases, the effects of boundary conditions and length diminish so that the frequency envelopes tend to converge.

Using molecular dynamics simulations and finite element method to study the mechanical properties of nanotube reinforced polyethylene and polyketone

2015 ◽  
Vol 29 (26) ◽  
pp. 1550155 ◽  
Author(s):  
S. Rouhi ◽  
Y. Alizadeh ◽  
R. Ansari ◽  
M. Aryayi
Keyword(s):  
Mechanical Properties ◽  
Molecular Dynamics ◽  
Finite Element ◽  
Molecular Dynamics Simulations ◽  
Polymer Matrix ◽  
Element Model ◽  
Important Change ◽  
Polymer Matrices ◽  
Transverse Tensile ◽  
Dynamics Simulations

Molecular dynamics simulations are used to study the mechanical behavior of single-walled carbon nanotube reinforced composites. Polyethylene and polyketone are selected as the polymer matrices. The effects of nanotube atomic structure and diameter on the mechanical properties of polymer matrix nanocomposites are investigated. It is shown that although adding nanotube to the polymer matrix raises the longitudinal elastic modulus significantly, the transverse tensile and shear moduli do not experience important change. As the previous finite element models could not be used for polymer matrices with the atom types other than carbon, molecular dynamics simulations are used to propose a finite element model which can be used for any polymer matrices. It is shown that this model can predict Young’s modulus with an acceptable accuracy.

scholarly journals Effects of area, aspect ratio and orientation of rectangular nanohole on the tensile strength of defective graphene – a molecular dynamics study

RSC Advances ◽  
2018 ◽  
Vol 8 (31) ◽  
pp. 17034-17043 ◽  
Author(s):  
Xinmao Qin ◽  
Wanjun Yan ◽  
Xiaotian Guo ◽  
Tinghong Gao
Keyword(s):  
Molecular Dynamics ◽  
Tensile Strength ◽  
Aspect Ratio ◽  
Molecular Dynamics Simulations ◽  
Aspect Ratios ◽  
Length Width ◽  
Defective Graphene ◽  
Dynamics Simulations

Molecular dynamics simulations with AIREBO potential are performed to investigate the effects of rectangular nanoholes with different areas, aspect ratios (length/width ratios) and orientations on the tensile strength of defective graphene.

A Multiscale Approach to Predict the Mechanical Properties of Copper Nanofoams

MRS Advances ◽  
2019 ◽  
Vol 4 (5-6) ◽  
pp. 293-298
Author(s):  
Hang Ke ◽  
Andres Garcia Jimenez ◽  
Ioannis Mastorakos
Keyword(s):  
Molecular Dynamics ◽  
Finite Element ◽  
Mechanical Behavior ◽  
Molecular Dynamics Simulations ◽  
Cell Structure ◽  
Element Model ◽  
Yield Function ◽  
Multiscale Approach ◽  
Element Analysis ◽  
Dynamics Simulations

ABSTRACTPure metallic nanofoams in the form of interconnected networks have shown strong potentials over the past few years in areas such as catalysts, batteries and plasmonics. However, they are often fragile and difficult to integrate in engineering applications. In order to better understand their deformation mechanisms, a multiscale approach is required to simulate the mechanical behavior of the nanofoams, although these materials will operate at the macroscale, they will still be maintaining an atomistic ordering. Hence, in this work we combine molecular dynamics (MD) and finite element analysis (FEA) to study the mechanical behavior of copper (Cu) nanofoams. Molecular dynamics simulations were performed to study the yield surface of a representative cell structure. The nanofoam structure has been generated by spinodal decomposition of binary alloy using an atomistic approach. Then, the information obtained from the molecular dynamics simulations in the form of yield function is transferred to the finite element model to study the macroscopic behavior of the Cu nanofoams. The simulated mechanical behavior of Cu nanofoams is in good agreement of the real experiment results.

Vibration of Single- and Double-Layered Graphene Sheets

2011 ◽  
Vol 2 (1) ◽  
Author(s):  
Behrouz Arash ◽  
Quan Wang
Keyword(s):  
Molecular Dynamics ◽  
Boundary Conditions ◽  
Molecular Dynamics Simulations ◽  
Nonlocal Parameter ◽  
Small Scale ◽  
Graphene Sheets ◽  
Elastic Model ◽  
Resonant Frequencies ◽  
Nonlocal Continuum Theory ◽  
Dynamics Simulations

Free vibration of single- and double-layered graphene sheets is investigated by employing nonlocal continuum theory and molecular dynamics simulations. Results show that the classical elastic model overestimated the resonant frequencies of the sheets by a percentage as high as 62%. The dependence of small-scale effects, sizes of sheets, boundary conditions, and number of layers on vibrational characteristic of single- and double-layered graphene sheets is studied. The resonant frequencies predicted by the nonlocal elastic plate theory are verified by the molecular dynamics simulations, and the nonlocal parameter is calibrated through the verification process. The simulation results reveal that the calibrated nonlocal parameter depends on boundary conditions and vibrational modes. The nonlocal plate model is found to be indispensable in vibration analysis of grapheme sheets with a length less than 8 nm on their sides.

Design and characterization of a hybrid soft gripper with active palm pose control

2020 ◽  
Vol 39 (14) ◽  
pp. 1668-1685 ◽  
Author(s):  
Vignesh Subramaniam ◽  
Snehal Jain ◽  
Jai Agarwal ◽  
Pablo Valdivia y Alvarado
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Composite Structure ◽  
Element Model ◽  
Open Loop ◽  
Aspect Ratios ◽  
Maximum Payload ◽  
Wide Range ◽  
Pose Control

The design and characterization of a soft gripper with an active palm to control grasp postures is presented herein. The gripper structure is a hybrid of soft and stiff components to facilitate integration with traditional arm manipulators. Three fingers and a palm constitute the gripper, all of which are vacuum actuated. Internal wedges are used to tailor the deformation of a soft outer reinforced skin as vacuum collapses the composite structure. A computational finite-element model is proposed to predict finger kinematics. Thanks to its active palm, the gripper is capable of grasping a wide range of part geometries and compliances while achieving a maximum payload of 30 N. The gripper natural softness enables robust open-loop grasping even when components are not properly aligned. Furthermore, the grasp pose of objects with various aspect ratios and compliances can be robustly maintained during manipulation at linear accelerations of up to 15 m/s2 and angular accelerations of up to 5.23 rad/s2.

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