Vibration and stability analysis of functionally graded CNT-reinforced composite beams with variable thickness on elastic foundation

2019 ◽  
Vol 233 (12) ◽  
pp. 2478-2489 ◽  
Author(s):  
Ali Mohseni ◽  
M Shakouri
Keyword(s):  
Carbon Nanotube ◽  
Variable Thickness ◽  
Volume Fraction ◽  
Differential Quadrature Method ◽  
Beam Theory ◽  
Composite Beams ◽  
Functionally Graded ◽  
Beam Shape ◽  
Reinforced Composite ◽  
Fixed Weight

The free vibration and buckling of functionally graded carbon nanotube reinforced composite beams with variable thickness resting on elastic foundations are investigated in the present paper. To account rotary inertia and transverse shear deformation effects, the Timoshenko beam theory is employed and governing equations are derived using Hamilton's principle. The obtained equations are solved using generalized differential quadrature method. Different carbon nanotube distributions through the thickness are considered, and the rule of mixture is used to describe the effective material properties of the functionally graded reinforced beams. The results are validated with available investigations, and the effects of boundary conditions, nanotube volume fraction and distribution, foundation and thickness ratio on both natural frequency and buckling load are studied. Finally, due to the weight optimization in aerospace and turbomachinery applications, the optimum beam shape and nanotube distribution are suggested to achieve the most capacity of bearing axial loads with fixed weight.

Thermal Buckling and Postbuckling Analysis of Functionally Graded Carbon Nanotube-Reinforced Composite Beams

2016 ◽  
Vol 846 ◽  
pp. 182-187 ◽  
Author(s):  
He Long Wu ◽  
Sritawat Kitipornchai ◽  
Jie Yang
Keyword(s):  
Carbon Nanotube ◽  
Volume Fraction ◽  
Slenderness Ratio ◽  
Beam Theory ◽  
Thermal Buckling ◽  
Functionally Graded ◽  
Equilibrium Path ◽  
Temperature Dependent ◽  
Reinforced Composite ◽  
Beam Thickness

Thermal buckling and postbuckling of functionally graded carbon nanotube-reinforced composite (FG-CNTRC) beams are investigated in this paper based on Timoshenko beam theory within the framework of von Kármán geometric nonlinearity. The material properties of FG-CNTRCs are assumed to be temperature-dependent and vary in the beam thickness direction. The governing equations are derived by employing Hamilton’s principle then discretized by using differential quadrature (DQ) method. An iterative scheme is used to obtain the critical buckling temperature and nonlinear thermal postbuckling equilibrium path of the FG-CNTRC beam. Numerical results are presented for FG-CNTRC beams hinged or clamped at both ends, with particular focuses on the effects of the volume fraction of carbon nanotubes (CNTs), slenderness ratio, and end supports on the thermal buckling and postbuckling characteristics.

A Type of Novel Nonlinear Distributions for Improving Significantly the Stiffness of Carbon Nanotube-Reinforced Composite Beams

2019 ◽  
Vol 17 (08) ◽  
pp. 1950057
Author(s):  
T. Vo-Duy ◽  
Tam T. Truong ◽  
K. Nguyen-Quang ◽  
T. Nguyen-Thoi ◽  
H. C. Vu-Do
Keyword(s):  
Carbon Nanotube ◽  
Volume Fraction ◽  
Shear Deformation Theory ◽  
Element Model ◽  
Composite Beams ◽  
Functionally Graded ◽  
Third Order ◽  
One Dimensional ◽  
Reinforced Composite ◽  
Unknown Solution

So far, the carbon nanotube (CNT) distributions have been still limited in the linear forms, which may lead to the limitations in maximizing the strength and potential of carbon nanotube reinforced composite (CNTRC) structures. This study, hence proposes a type of novel CNTs distribution for improving the stiffness of CNTRC beams. The distributions are in the nonlinear forms and ensure the same total CNT volume fraction along the thickness of structures. For demonstrating, the effectiveness of the proposed CNT distributions, the static, free vibration and buckling analyses of functionally graded carbon nanotube (FG-CNT) reinforced composite beams using the new CNT distributions are conducted and one-dimensional NURSB basis functions based on the third-order shear deformation theory (TSDT) are utilized to describe the exact geometry and to approximate the unknown solution in finite element model of the beam. The numerical investigations of the geometric and material parameters reveal that the new nonlinear CNT distributions can help increase the normalized frequency, buckling load and the nondimensional central deflection to the maxima of 8%, 16% and 16% respectively, in some conditions of geometric parameters.

Frequency optimization of laminated functionally graded carbon nanotube reinforced composite quadrilateral plates using smoothed FEM and evolution algorithm

2017 ◽  
Vol 52 (14) ◽  
pp. 1971-1986 ◽  
Author(s):  
T Vo-Duy ◽  
T Truong-Thi ◽  
V Ho-Huu ◽  
T Nguyen-Thoi
Keyword(s):  
Carbon Nanotube ◽  
Optimization Problem ◽  
Volume Fraction ◽  
Differential Evolution Algorithm ◽  
Composite Plates ◽  
Functionally Graded ◽  
Optimization Approach ◽  
Reinforced Composite ◽  
Design Variables ◽  
Evolution Algorithm

The paper presents an efficient numerical optimization approach to deal with the optimization problem for maximizing the fundamental frequency of laminated functionally graded carbon nanotube-reinforced composite quadrilateral plates. The proposed approach is a combination of the cell-based smoothed discrete shear gap method (CS-DSG3) for analyzing the first natural frequency of the functionally graded carbon nanotube reinforced composite plates and a global optimization algorithm, namely adaptive elitist differential evolution algorithm (aeDE), for solving the optimization problem. The design variables are the carbon nanotube orientation in the layers and constrained in the range of integer numbers belonging to [−900 900]. Several numerical examples are presented to investigate optimum design of quadrilateral laminated functionally graded carbon nanotube reinforced composite plates with various parameters such as carbon nanotube distribution, carbon nanotube volume fraction, boundary condition and number of layers.

Free Vibration and Buckling Analysis of Sandwich Beams with Functionally Graded Carbon Nanotube-Reinforced Composite Face Sheets

2015 ◽  
Vol 15 (07) ◽  
pp. 1540011 ◽  
Author(s):  
Helong Wu ◽  
Sritawat Kitipornchai ◽  
Jie Yang
Keyword(s):  
Carbon Nanotube ◽  
Free Vibration ◽  
Volume Fraction ◽  
Slenderness Ratio ◽  
Micromechanical Model ◽  
Sandwich Beam ◽  
Sheet Thickness ◽  
Functionally Graded ◽  
Sandwich Beams ◽  
Reinforced Composite

This paper investigates the free vibration and elastic buckling of sandwich beams with a stiff core and functionally graded carbon nanotube reinforced composite (FG-CNTRC) face sheets within the framework of Timoshenko beam theory. The material properties of FG-CNTRCs are assumed to vary in the thickness direction, and are estimated through a micromechanical model. The governing equations and boundary conditions are derived by using Hamilton's principle and discretized by employing the differential quadrature (DQ) method to obtain the natural frequency and critical buckling load of the sandwich beam. A detailed parametric study is conducted to study the effects of carbon nanotube volume fraction, core-to-face sheet thickness ratio, slenderness ratio, and end supports on the free vibration characteristics and buckling behavior of sandwich beams with FG-CNTRC face sheets. The vibration behavior of the sandwich beam under an initial axial force is also discussed. Numerical results for sandwich beams with uniformly distributed carbon nanotube-reinforced composite (UD-CNTRC) face sheets are also provided for comparison.

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