scholarly journals Analysis of longitudinal vibration band gaps in periodic carbon nanotube intramolecular junctions using finite element method

AIP Advances ◽  
2015 ◽  
Vol 5 (12) ◽  
pp. 127107 ◽  
Author(s):  
Jiaqian Li ◽  
Haijun Shen
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Carbon Nanotube ◽  
Longitudinal Vibration ◽  
Band Gaps ◽  
Vibration Band ◽  
Element Method

Vibration band gaps for elastic metamaterial rods using wave finite element method

2016 ◽  
Vol 79 ◽  
pp. 192-202 ◽  
Author(s):  
E.D. Nobrega ◽  
F. Gautier ◽  
A. Pelat ◽  
J.M.C. Dos Santos
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Band Gaps ◽  
Vibration Band ◽  
Element Method

Vibration Isolation Design for Periodical Stiffened Shells by the Wave Finite Element Method

2017 ◽  
Author(s):  
Jie Hong ◽  
Xueqing He ◽  
Dayi Zhang ◽  
Yanhong Ma
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Band Gap ◽  
Vibration Isolation ◽  
Band Gaps ◽  
Vibration Band ◽  
Frequency Range ◽  
Gap Characteristics ◽  
Plates And Shells ◽  
Element Method

Thin plates and shells are widely used to reduce the weight in modern mechanical systems, in particularly for the aeronautic and astronautical machineries. These thin structures can result in intensive modes, and lead to the difficulty on the suppression of vibration. The excessive vibration of casing can not only lead to the failure itself but also has a significant influence on the related external pipelines and other attachments which could cause the fatigue failure for the aero-engine casings. A proper method is needed to investigate the dynamic characteristics for these casings, and to be potentially further used for the vibration isolation design. Periodic structure has received a great deal of attentions for its band gap characteristics. Sound and other vibration can be forbidden to propagate in its band gap. With regard to the applications in aero-engines, the article provides one probable vibration isolation method for the stiffened plates and shells with high strength-to-weight ratio and with periodic configuration characteristics. The vibration characteristics of the stiffened shell are usually difficult to be acquired, and there is neither an analytical solution for the complicated stiffeners configuration. Therefore, a Wave finite element method (FEM) based on the wave theory and finite element method, which can solve the dynamic response and band gap characteristics of casings with wide frequency band is presented. Taking the characteristics of the curvature into account, it is proposed for how to confirm the periodic boundaries of the shells. Moreover, the finite element model built by ANSYS is combined with MATLAB program, and the validity of Wave FEM is proved in shell with different boundaries including free-clamped boundary and free-free boundary. The results reveal that with the increase of stiffeners’ width, wider frequency range and larger attenuating ability appear in the vibration band gap. While with the increase of stiffeners’ thickness, neither the variety of the attenuating capability nor of the frequency range of band gaps is monotone. And the local resonance of stiffeners is obvious, the corresponding band gaps’ contribution to the whole system is little. Moreover, three typical configurations-hexagonal, square and triangular are considered. The configurations of stiffeners have distinct characteristics on the dispersion relation, if the weight problems are not taken into account, the square honeycomb is better than the others.

Effect of aluminum carbide interphase on the thermomechanical behavior of carbon nanotube/aluminum nanocomposites

2018 ◽  
Vol 233 (9) ◽  
pp. 1843-1853 ◽  
Author(s):  
Xiaolong Shi ◽  
Mohammad Kazem Hassanzadeh Aghdam ◽  
Reza Ansari
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Thermal Expansion ◽  
Carbon Nanotube ◽  
Volume Fraction ◽  
Chemical Interaction ◽  
Coefficient Of Thermal Expansion ◽  
Aluminum Matrix ◽  
Aluminum Carbide ◽  
Element Method

The objective of this work is to investigate the coefficient of thermal expansion of carbon nanotube reinforced aluminum matrix nanocomposites in which aluminum carbide (Al4C3) interphase formed due to chemical interaction between the carbon nanotube and aluminum matrix is included. To this end, the micromechanical finite element method along with a representative volume element, which incorporates, carbon nanotube, interphase, and aluminum matrix is employed. The emphasis is mainly placed on the effect of Al4C3 interphase on the coefficient of thermal expansion of aluminum nanocomposites with random microstructures. The effects of interphase thickness, carbon nanotube diameter, and volume fraction on the thermomechanical response of aluminum nanocomposite are discussed. The results reveal that the effect of Al4C3 interphase on the coefficient of thermal expansion of the aluminum nanocomposites becomes more significant with (i) increasing the coefficient of thermal expansion volume fraction, (ii) decreasing the coefficient of thermal expansion diameter, and (iii) increasing the interphase thickness. It is clearly observed that the coefficient of thermal expansion varies nonlinearly with the carbon nanotube diameter; however, it decreases linearly as the carbon nanotube volume fraction increases. Furthermore, the axial and transverse coefficient of thermal expansions of aligned continuous and discontinuous carbon nanotube-reinforced aluminum nanocomposites with Al4C3 interphase are predicted. Also, the presented finite element method results are compared with the available experiment in the literature, rule of mixture, and concentric cylinder model results.

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