Plasticity of Carbon Nanotubes under a Combined Axial and Torsional Stress
0
Citation
0
Reference
20
Related Paper
Cite
The mechanical responses of several different carbon nanotube systems to applied torsional loading at various temperatures are examined using classical molecular dynamics simulations, and the results are interpreted and compared to the predictions of continuum mechanics theory. The specific materials considered include filled and chemically functionalized, individual single-walled and multiwalled carbon nanotubes, as well as bundled carbon nanotubes. The simulations indicate that the mechanical responses to the torsional loading are buckling and that all the carbon nanotube systems considered are highly elastic. They also indicate that the critical buckling moment can be increased by the presence of filling materials and inner carbon nanotubes, and that the amount of this increase depends on the kind of filling materials and the number of inner tubes. The simulations further show that the critical buckling moment of a single carbon nanotube in a bundle is higher than that of the individual nanotubes alone. In addition, the dependence of the torsional stiffness on the diameters of the nanotubes is found to vary as K∼D2.99, where K is the torsional stiffness and D is the nanotube diameter, and the torsional shear modulus is found to be relatively independent of the nanotube diameter and length, in good agreement with predictions from continuum mechanics theory. Lastly, the simulations indicate that the critical buckling moment can be modified by adjusting the system temperature and through chemical functionalization of the carbon nanotube walls.
Shear modulus
Cite
Citations (83)
Carbon nanotubes with excellent mechanical properties can be utilised as nanoscale reinforcement to carry loads in composite structures. External loads are transferred to carbon nanotubes via the surrounding matrix, through the interfacial shear stress. In this work, the interaction and stress transfer in double-walled carbon nanotube- reinforced composites are investigated. A cylindrical representative element volume containing the double-walled carbon nanotubes and matrix is employed to determine the interfacial shear stress and longitudinal axial stress in the double-walled carbon nanotube. The theoretical predictions of the interfacial shear stress and longitudinal axial stress are verified with the finite element results. The effects of the aspect ratio and volume fraction on the stress transfer are investigated through a parametric study. Numerical results show that stresses transferred to double-walled carbon nanotubes are increasing with the increases of the volume fraction and aspect ratio. It demonstrates that a better load transfer efficiency can be achieved with larger volume fraction and aspect ratio.
Volume fraction
Aspect ratio (aeronautics)
Representative elementary volume
Cite
Citations (2)
Shear modulus
Nanoelectromechanical systems
Buckle
Cite
Citations (29)
Torsional buckling of single-walled carbon nanotubes filled with light weight molecular via molecular dynamics is reported. The model accounts for the deformation of CNTs, and interactions among gas molecules; between gas and carbon atoms. The effect of particle loading is predicted to significantly change CNT’s critical torsional moment and stiffness. This is therefore an approach by which the torsional mechanical properties and oscillation frequencies of carbon nanotubes may be tuned. Importantly, the predicted changes in torsional siffness are unique relative to conventional linear elastic materials and are indicative of nonlinear oscillations due to nonlinear mechanical effects. CNTs subjects to large deformations reversibly switch into different morphological patterns. Each shape change corresponds to an abrupt release of energy and a singularity in the stress-strain curve. At higher torsional angle, van der Waals (VDW: He, Ar, H 2 ) molecules reveal a stability effect on carbon nanotubes.
Shear modulus
Strain energy
Cite
Citations (1)
Strain (injury)
Cite
Citations (0)
Strain (injury)
Cite
Citations (0)
Zigzag
Chirality
Tensile testing
Tensile strain
Cite
Citations (1)
Abstract This study is an attempt to show the impacts of surface irregularity and compressive initial stresses on the torsional vibration of a single-walled carbon nanotube (SWCNT). The governing equation and corresponding closed-form solutions were derived with the aid of Hamilton's principle. Then, the natural frequencies were obtained analytically and the influences of surface irregularity and compressive initial stresses on the torsional vibration were studied in detail. Numerical results analyzing the torsional vibration incorporating compressive initial stress effects were discussed and presented graphically. The effects of surface irregularity on the natural frequency of torsional vibrations of nanomaterials, especially for SWCNTs, have not been investigated before, and most of the previous research works have been carried for a regular carbon nanotube. Therefore, it must be emphasized that the torsional vibrations of irregular SWCNTs are novel and applicable for the design of nano-oscillators and nanodevices, in which SWCNTs act as the most prevalent nanocomposite structural element. The analytical solutions and numerical results revealed that the surface irregularity and compressive initial stress have notable effects on the natural frequency of torsional vibrations. It has been observed that, as the surface irregularity and compressive initial stress parameters increase, the torsional natural frequency of vibrations of SWCNTs also increases. Since SWCNTs have very small size, they are always subject to initial stresses from different resources; therefore, understanding the influences of compressive initial stresses on the torsional frequency of nanotubes helps the engineers and researchers to design proper nanodevices for different applications with irregular shapes.
Torsional Vibration
Natural frequency
Cite
Citations (4)
Resonance frequency change due to axial‐strain‐induced torsional (ASIT) rotation of single‐walled carbon nanotubes (SWCNTs) was investigated via the atomistic simulation method. The deformations of SWCNTs under axial strains were simulated, and the simulation cases with fixed edges were compared to those with relaxed edges to investigate the effect of the ASIT response. The axial‐force differences due to the ASIT response for the chiral SWCNTs increased with increasing the axial strain and then, the fundamental frequencies were changed. Such properties due to the ASIT response can be importantly applied to developing CNT‐based nanoelectromechanical system devices.
Strain (injury)
Nanoelectromechanical systems
Cite
Citations (0)