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

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.

Author(s):  
Saeed Rouhi ◽  
Tayyeb Pour Reza ◽  
Babak Ramzani ◽  
Saeed Mehran

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.


2015 ◽  
Vol 29 (26) ◽  
pp. 1550155 ◽  
Author(s):  
S. Rouhi ◽  
Y. Alizadeh ◽  
R. Ansari ◽  
M. Aryayi

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.


Author(s):  
R Ansari ◽  
S Rouhi

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.


RSC Advances ◽  
2020 ◽  
Vol 10 (24) ◽  
pp. 14353-14359
Author(s):  
Yudi Rosandi ◽  
Hoang-Thien Luu ◽  
Herbert M. Urbassek ◽  
Nina Gunkelmann

Alumina coatings increase the ductility of aluminum nanowires by reorganization of the Al–O layer and stabilization of bonds.


Author(s):  
Wei Yang ◽  
Jyhwen Wang

A generalized analytical solution of mechanical and thermal induced stresses in a multi-layer composite cylinder is presented. Based on the compatibility condition at the interfaces, an explicit solution of mechanical stress due to inner and outer surface pressures and thermal stress due to temperature change is derived. A finite element model is also developed to provide the comparison with the analytical solution. It was found that the analytical solutions are in good agreement with finite element analysis result. The analytical solution shows the non-linear dependency of thermal stress on the diameters, thicknesses and the material properties of the layers. It is also shown that the radial and circumferential thermal stresses depend linearly on the coefficients of thermal expansion of the materials and the temperature change. As demonstrated, this solution can also be applied to analyze the thermo-mechanical behavior of pipes coated with functionally graded materials.


2012 ◽  
Vol 730-732 ◽  
pp. 543-548
Author(s):  
Alexandre Correia ◽  
S. Mohsen Valashani ◽  
Francisco Pires ◽  
Ricardo Simões

Molecular dynamics simulations were employed to analyze the mechanical properties of polymer-based nanocomposites with varying nanofiber network parameters. The study was focused on nanofiber aspect ratio, concentration and initial orientation. The reinforcing phase affects the behavior of the polymeric nanocomposite. Simulations have shown that the fiber concentration has a significant effect on the properties, with higher loadings resulting in higher stress levels and higher stiffness, matching the general behavior from experimental knowledge in this field. The results also indicate that, within the studied range, the observed effect of the aspect ratio and initial orientation is smaller than that of the concentration, and that these two parameters are interrelated.


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