scholarly journals ELASTIC DAMPER BASED ON THE CARBON NANOTUBE BUNDLE

2020 ◽  
Vol 18 (1) ◽  
pp. 001 ◽  
Author(s):  
Leysan Kh. Rysaeva ◽  
Elena A. Korznikova ◽  
Ramil T. Murzaev ◽  
Dina U. Abdullina ◽  
Aleksey A. Kudreyko ◽  
...  
Keyword(s):  
Phase Transition ◽  
Carbon Nanotube ◽  
Order Phase Transition ◽  
Degrees Of Freedom ◽  
High Efficiency ◽  
Mechanical Response ◽  
Compressive Strain ◽  
Period Doubling ◽  
Chain Model ◽  
Nanotube Bundle

Mechanical response of the carbon nanotube bundle to uniaxial and biaxial lateral compression followed by unloading is modeled under plane strain conditions. The chain model with a reduced number of degrees of freedom is employed with high efficiency. During loading, two critical values of strain are detected. Firstly, period doubling is observed as a result of the second order phase transition, and at higher compressive strain, the first order phase transition takes place when carbon nanotubes start to collapse. The loading-unloading stress-strain curves exhibit a hysteresis loop and, upon unloading, the structure returns to its initial form with no residual strain. This behavior of the nanotube bundle can be employed for the design of an elastic damper.

scholarly journals Mechanical Response of Carbon Nanotube Bundle to Lateral Compression

Computation ◽  
2020 ◽  
Vol 8 (2) ◽  
pp. 27 ◽  
Author(s):  
Dina U. Abdullina ◽  
Elena A. Korznikova ◽  
Volodymyr I. Dubinko ◽  
Denis V. Laptev ◽  
Alexey A. Kudreyko ◽  
...  
Keyword(s):  
Phase Transition ◽  
Carbon Nanotube ◽  
Order Phase Transition ◽  
Mechanical Response ◽  
Van Der Waals ◽  
Van Der Waals Interactions ◽  
Structure Evolution ◽  
Biaxial Compression ◽  
Chain Model ◽  
Bending Rigidity

Structure evolution and mechanical response of the carbon nanotube (CNT) bundle under lateral biaxial compression is investigated in plane strain conditions using the chain model. In this model, tensile and bending rigidity of CTN walls, and the van der Waals interactions between them are taken into account. Initially the bundle in cross section is a triangular lattice of circular zigzag CNTs. Under increasing strain control compression, several structure transformations are observed. Firstly, the second-order phase transition leads to the crystalline structure with doubled translational cell. Then the first-order phase transition takes place with the appearance of collapsed CNTs. Further compression results in increase of the fraction of collapsed CNTs at nearly constant compressive stress and eventually all CNTs collapse. It is found that the potential energy of the CNT bundle during deformation changes mainly due to bending of CNT walls, while the contribution from the walls tension-compression and from the van der Waals energies is considerably smaller.

scholarly journals EVOLUTION OF THE CARBON NANOTUBE BUNDLE STRUCTURE UNDER BIAXIAL AND SHEAR STRAINS

2020 ◽  
pp. 525
Author(s):  
Leysan Kh. Rysaeva ◽  
Dmitry V. Bachurin ◽  
Ramil T. Murzaev ◽  
Dina U. Abdullina ◽  
Elena A. Korznikova ◽  
...  
Keyword(s):  
Carbon Nanotube ◽  
Shear Strain ◽  
Cross Sections ◽  
Degrees Of Freedom ◽  
Shear Bands ◽  
Volumetric Strain ◽  
Structural Evolution ◽  
Biaxial Compression ◽  
Chain Model ◽  
Nanotube Bundle

Close packed carbon nanotube bundles are materials with highly deformable elements, for which unusual deformation mechanisms are expected. Structural evolution of the zigzag carbon nanotube bundle subjected to biaxial lateral compression with the subsequent shear straining is studied under plane strain conditions using the chain model with a reduced number of degrees of freedom. Biaxial compression results in bending of carbon nanotubes walls and formation of the characteristic pattern, when nanotube cross-sections are inclined in the opposite directions alternatively in the parallel close-packed rows. Subsequent shearing up to a certain shear strain leads to an appearance of shear bands and vortex-like displacements. Stress components and potential energy as the functions of shear strain for different values of the biaxial volumetric strain are analyzed in detail. A new mechanism of carbon nanotube bundle shear deformation through cooperative, vortex-like displacements of nanotube cross sections is reported.

Unjamming in Dry Granular Matter: Second-Order Phase Transition between Fragile Solid and Dry Fluid (Bearing) by Intermittency.

2011 ◽  
Vol 172-174 ◽  
pp. 1106-1111 ◽  
Author(s):  
Nicolas Rivier ◽  
Jean Yves Fortin
Keyword(s):  
Phase Transition ◽  
Order Phase Transition ◽  
Degrees Of Freedom ◽  
Granular Matter ◽  
Load Ratio ◽  
Low Energies ◽  
Critical Contact ◽  
Shear Jamming ◽  
Tangential Friction ◽  
Second Order Phase Transition

Dry granular matter, with infinite tangential friction, is modeled as a connected graph ofgrains linked by purely repulsive contacts. The degrees of freedom of a grain are non-slip rotationon, and disconnection from another. The material stability under shear (jamming) is ensured by oddcircuits of grains in contact that prevent the grains from rolling on each other. A dense granularmaterial with high stiffness-to-load ratio has two possible states: fragile solid, blocked by odd circuits,and dry fluid or bearing, in the absence of odd circuits, that flows under shear by creation and glide ofa pair of dislocations as in plasticity of continuous media. In this paper, we introduce the notions of blob, a region of the material containing only even circuits, and of critical contact that closes an oddcircuit. The granular material is then represented, at low energies and critical applied shear, as a chainof blobs connected by critical contacts. The transition between dry fluid and fragile solid occurs byintermittency.

Rotobreather in a carbon nanotube bundle

2020 ◽  
Vol 05 (03) ◽  
pp. 2050010
Author(s):  
Sergey V. Dmitriev ◽  
Alexander S. Semenov ◽  
Alexander V. Savin ◽  
Marat A. Ilgamov ◽  
Dmitry V. Bachurin
Keyword(s):  
Nonlinear Dynamics ◽  
Mechanical Properties ◽  
Carbon Nanotube ◽  
Kinetic Energy ◽  
Degrees Of Freedom ◽  
Rotational Energy ◽  
Energy Localization ◽  
Dynamics Model ◽  
Angular Velocities ◽  
Nanotube Bundle

Carbon nanotube (CNT) bundles exhibit unusual mechanical properties, but nonlinear dynamics and possible energy localization in such systems have not yet been analyzed. The dynamics of a rotobreather in the form of a CNT rotating around its axis and placed in an array of similar CNTs is analyzed using a molecular dynamics model with a reduced number of degrees of freedom. The height of the Peierls–Nabarro potential associated with the discreteness of CNTs is estimated. It is found that if a CNT is given rotational kinetic energy not sufficient to overcome the Peierls–Nabarro potential, it does not rotate. Several resonant angular velocities are identified at which the rotating CNT loses its kinetic energy relatively quickly and eventually stops rotating. CNT with a sufficiently large, non-resonant angular velocity emits the rotational energy very slowly.

scholarly journals Generalized Ehrenfest's equations and phase transition in black holes

2015 ◽  
Vol 24 (03) ◽  
pp. 1550029 ◽  
Author(s):  
Mohammad Bagher Jahani Poshteh ◽  
Behrouz Mirza ◽  
Fatemeh Oboudiat
Keyword(s):  
Phase Transition ◽  
Black Holes ◽  
Critical Point ◽  
Order Phase Transition ◽  
Arbitrary Number ◽  
Degrees Of Freedom ◽  
Second Order ◽  
First Law Of Thermodynamics ◽  
Three Degrees Of Freedom ◽  
Second Order Phase Transition

In this paper, we generalize Ehrenfest's equations to systems having two work terms, i.e. systems with three degrees of freedom. For black holes with two work terms we obtain nine equations instead of two to be satisfied at the critical point of a second-order phase transition. We finally generalize this method to a system with an arbitrary number of degrees of freedom and found there is [Formula: see text] equations to be satisfied at the point of a second-order phase transition where N is number of work terms in the first law of thermodynamics.

PTC MWCNT/DI-water switchable composites

2015 ◽  
Vol 3 (10) ◽  
pp. 5270-5274 ◽  
Author(s):  
Pengcheng Sun ◽  
Yun Huang ◽  
Jun Yang ◽  
Guoan Cheng ◽  
Ruiting Zheng
Keyword(s):  
Phase Transition ◽  
Carbon Nanotube ◽  
Order Phase Transition ◽  
Contrast Ratio ◽  
First Order ◽  
First Order Phase Transition ◽  
Multi Walled Carbon Nanotube ◽  
First Order Phase ◽  
Thermal Conductivities

In this paper, we study the electrical and thermal conductivities of multi-walled carbon nanotube (MWCNT)/DI-water composites via first order phase transition. Around 0 °C, the contrast ratio of electrical and thermal conductivities reaches 1250 and 3.58 times, with PTC and NTC effects respectively.

scholarly journals Chain Model for Carbon Nanotube Bundle under Plane Strain Conditions

Materials ◽  
2019 ◽  
Vol 12 (23) ◽  
pp. 3951 ◽  
Author(s):  
Elena A. Korznikova ◽  
Leysan Kh. Rysaeva ◽  
Alexander V. Savin ◽  
Elvira G. Soboleva ◽  
Evgenii G. Ekomasov ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Plane Strain ◽  
Degrees Of Freedom ◽  
High Pressures ◽  
Mechanical Response ◽  
Solid Lubricants ◽  
Equilibrium Structure ◽  
Van Der Waals Interactions ◽  
Chain Model ◽  
Bending Rigidity

Carbon nanotubes (CNTs) have record high tensile strength and Young’s modulus, which makes them ideal for making super strong yarns, ropes, fillers for composites, solid lubricants, etc. The mechanical properties of CNT bundles have been addressed in a number of experimental and theoretical studies. The development of efficient computational methods for solving this problem is an important step in the design of new CNT-based materials. In the present study, an atomistic chain model is proposed to analyze the mechanical response of CNT bundles under plane strain conditions. The model takes into account the tensile and bending rigidity of the CNT wall, as well as the van der Waals interactions between walls. Due to the discrete character of the model, it is able to describe large curvature of the CNT wall and the fracture of the walls at very high pressures, where both of these problems are difficult to address in frame of continuum mechanics models. As an example, equilibrium structures of CNT crystal under biaxial, strain controlled loading are obtained and their thermal stability is analyzed. The obtained results agree well with previously reported data. In addition, a new equilibrium structure with four SNTs in a translational cell is reported. The model offered here can be applied with great efficiency to the analysis of the mechanical properties of CNT bundles composed of single-walled or multi-walled CNTs under plane strain conditions due to considerable reduction in the number of degrees of freedom.

Second Order Phase Transition in a Highly Chaotic Hamiltonian System with Many Degrees of Freedom

1997 ◽  
Vol 07 (04) ◽  
pp. 839-847 ◽  
Author(s):  
Yoshiyuki Y. Yamaguchi
Keyword(s):  
Phase Transition ◽  
Hamiltonian System ◽  
Order Phase Transition ◽  
Degrees Of Freedom ◽  
Initial Conditions ◽  
Phenomenological Theory ◽  
Critical Energy ◽  
Second Order ◽  
Slow Relaxations ◽  
Second Order Phase Transition

Second order phase transition is numerically investigated in a Hamiltonian system with many degrees of freedom. Slow relaxations of power type are observed for some initial conditions at critical energy of phase transition. This is consisent with a result of a phenomenological theory of statistical mechanics. On the other hand, the slow relaxations show that the system stays in non-equilibrium states for a while, and that phenomenon does not agree with a result of the theory. To understand the slow relaxation, theories for perturbed systems cannot be applied since near the critical energy the system is highly chaotic rather than nearly integrable. The thresholds of the highly chaotic systems is different from the critical energy of phase transition.

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