Nuttawit Wattanasakulpong

Bio: Nuttawit Wattanasakulpong is an academic researcher from Mahanakorn University of Technology. The author has contributed to research in topics: Vibration & Boundary value problem. The author has an hindex of 17, co-authored 26 publications receiving 1023 citations.

Linear and nonlinear vibration analysis of elastically restrained ends FGM beams with porosities

Abstract: Linear and nonlinear vibration problems of elastically end restrained beams made of functionally graded materials (FGMs) are investigated in this present paper. Due to porosities, possibly occurring inside FGMs during fabrication, it is therefore necessary to consider the vibration behavior of beams having porosities in this investigation. The rule of mixture is modified to describe and approximate material properties of the functionally graded beams with porosity phases. The differential transformation method (DTM) is employed to solve linear and nonlinear vibration responses of FGM beams with different kinds of elastic supports. The effects of material property distribution, spring constants and porosity volume fraction on linear and nonlinear frequencies of FGM beams are also presented and discussed in detail.

Flexural vibration of imperfect functionally graded beams based on Timoshenko beam theory: Chebyshev collocation method

Abstract: Flexural vibration analysis of beams made of functionally graded materials (FGMs) with various boundary conditions is considered in this paper. Due to technical problems during FGM fabrication, porosities and micro-voids can be created inside FGM samples which may lead to the reduction in density and strength of materials. In this investigation, the FGM beams are assumed to have even and uneven distributions of porosities over the beam cross-section. The modified rule of mixture is used to approximate material properties of the FGM beams including the porosity volume fraction. In order to cover the effects of shear deformation, axial and rotary inertia, the Timoshenko beam theory is used to form the coupled equations of motion for describing dynamic behavior of the beams. To solve such a problem, Chebyshev collocation method is employed to find natural frequencies of the beams supported by different end conditions. Based on numerical results, it is revealed that FGM beams with even distribution of porosities have more significant impact on natural frequencies than FGM beams with uneven porosity distribution.

Analytical solutions for bending, buckling and vibration responses of carbon nanotube-reinforced composite beams resting on elastic foundation

Abstract: The objective of the present paper is to investigate the bending, buckling and vibration behaviors of carbon nanotube-reinforced composite (CNTRC) beams. The beams resting on the Pasternak elastic foundation, including a shear layer and Winkler spring, are considered. The single-walled carbon nanotubes (SWCNTs) are aligned and distributed in polymeric matrix with different patterns of reinforcement. The material properties of the CNTRC beams are estimated by using the rule of mixture. Various shear deformation theories are employed to deal with the problems. The mathematical models provided in this paper are numerically validated by comparison with some available results. New results of bending, buckling and vibration analyses of CNTRC beams based on several higher-order shear deformation theories are presented and discussed in details. Several aspects of beam types, spring constant factors, carbon nanotube volume fraction, etc., are taken into investigation.

Exact solutions for static and dynamic analyses of carbon nanotube-reinforced composite plates with Pasternak elastic foundation

Abstract: This paper investigates static and dynamic behavior of carbon nanotube-reinforced composite plates resting on the Pasternak elastic foundation including shear layer and Winkler springs. The plates are reinforced by single-walled carbon nanotubes with four types of distributions of uni-axially aligned reinforcement material. Exact solutions obtained from closed-form formulation based on generalized shear deformation plat theory which can be adapted to various plate theories for bending, buckling and vibration analyses of such plates are presented. An accuracy of the present solutions is validated numerically by comparisons with some available results in the literature. Various significant parameters of carbon nanotube volume fraction, spring constant factors, plate thickness and aspect ratios, etc. are taken into investigation. According to the numerical results, it is revealed that the deflection of the plates is found to decrease as the increase of spring constant factors; while, the buckling load and natural frequency increase as the increment of the factors for every type of plate.

Buckling isogeometric analysis of functionally graded plates under combined thermal and mechanical loads

Abstract: Practical applications such as airplane wings are usually subjected to combined thermal and mechanical loads, and they hence are prone to buckling failure. Preceding works on the buckling of advanced materials, e.g., functionally graded materials, under combined thermal and mechanical loads are rather rare in literature. In this paper, we report new numerical results of thermal-mechanical buckling of functionally graded rectangular and skew plates (FGPs) under combined thermal and mechanical loads. The numerical responses of buckling are computed using isogeometric analysis (IGA) based on the first-order shear deformation plate theory (FSDT) without shear-locking effect. We present formulations and then provide validation of numerical results computed by the proposed formulation against reference existing solutions. Parametric study is also performed to explore insight into the effects of various numerical aspect ratios such as gradient index, plate aspect ratio, loading type, skew angle, and boundary condition, etc. on mechanical response of FGPs. The stability diagrams are also presented.

Mechanical analysis of functionally graded carbon nanotube reinforced composites: A review

Abstract: Research activities related to functionally graded materials (FGMs) have increased rapidly in recent years. The superlative properties of carbon nanotubes, i.e. high strength, high stiffness, high aspect ratio and low density have made them an excellent reinforcement for composite materials. Inspired by the concept of FGMs, the functionally graded (FG) pattern of reinforcement has been applied for functionally graded carbon nanotube reinforced composite (FG-CNTRC) materials. This paper attempts to identify and highlight topics relevant to FG-CNTRC and reviews the recent research works that have been reported in these topics. The present review includes: (i) a brief introduction of carbon nanotube reinforced composite (CNTRC) material; (ii) a review of mechanical analysis of FG-CNTRC; and (iii) a detailed discussion on the recent advances of FG-CNTRC and its prospect.

Free vibration and elastic buckling of functionally graded porous beams reinforced by graphene platelets

Abstract: This paper studies free vibration and elastic buckling of functionally graded porous nanocomposite beams where the internal pores and graphene platelets (GPLs) are layer-wise distributed in the matrix either uniformly or non-uniformly according to three different patterns. A multilayer beam model is proposed with material parameters varying across layers to achieve graded distributions in both porosity and nanofillers. Mechanical properties of closed-cell cellular solids under Gaussian Random Field scheme are used to determine the variation of Poisson's ratio and the relationship between porosity coefficients and mass density. The elastic modulus of the nanocomposite is obtained by using Halpin-Tsai micromechanics model. Theoretical formulations are based on Timoshenko beam theory and Ritz method is employed to obtain the dimensionless fundamental natural frequency and critical buckling load of porous nanocomposite beams. A comprehensive parametric study is carried out, with a particular focus on the effects of weight fraction, distribution pattern, geometry and size of GPL reinforcements on the free vibration and buckling behaviors of the nanocomposite beam with different metal matrixes and porosity coefficients. The results indicate that the effective stiffness of the porous nanocomposite beam can be best improved when both porosity distribution and GPL dispersion pattern are non-uniform but symmetric.

Buckling and postbuckling of functionally graded multilayer graphene platelet-reinforced composite beams

Abstract: This paper investigates the buckling and postbuckling behaviours of functionally graded multilayer nanocomposite beams reinforced with a low content of graphene platelets (GPLs) resting on an elastic foundation. It is assumed that GPLs are randomly oriented and uniformly dispersed in each individual GPL-reinforced composite (GPLRC) layer with its weight fraction varying layerwise along the thickness direction. The effective material properties of each layer are estimated by the Halpin-Tsai micromechanics model. The nonlinear governing equations of the beam on an elastic foundation are derived within the framework of the first-order shear deformation beam theory then are converted into a nonlinear algebraic system by using the differential quadrature method. A detailed parametric study is carried out to examine the effects of the distribution pattern, weight fraction, geometry and size of GPL nanofillers, foundation stiffness parameters, slenderness ratio and boundary conditions on the buckling and postbuckling behaviours. The results show that GPLs have a remarkable reinforcing effect on the buckling and postbuckling of nanocomposite beams.

Wave propagation in functionally graded plates with porosities using various higher-order shear deformation plate theories

Abstract: In this work, various higher-order shear deformation plate theories for wave propagation in functionally graded plates are developed. Due to porosities, possibly occurring inside functionally graded materials (FGMs) during fabrication, it is therefore necessary to consider the wave propagation in plates having porosities in this study. The developed refined plate theories have fewer number of unknowns and equations of motion than the first-order shear deformation theory, but accounts for the transverse shear deformation effects without requiring shear correction factors. The rule of mixture is modified to describe and approximate material properties of the functionally graded plates with porosity phases. The governing equations of the wave propagation in the functionally graded plate are derived by employing the Hamilton

Recent development in modeling and analysis of functionally graded materials and structures

Abstract: In this article, an extensive review related to the structural response of the functionally graded materials (FGMs) and structures have been presented. These are high technology materials developed by a group scientist in the late 1980's in Japan. The emphasis has been made here, to present the structural characteristics of FGMs plates/shells under thermo-electro-mechanical loadings under various boundary and environmental conditions. This paper also provides an overview of different fabrication procedures and the future research directions which is required to implement these materials in the design and analysis appropriately. The expected outcome of present review can be treated as milestone for future studies in the area of high technology materials and structures, and would be definitely advantageous for the researchers, scientists, and designers working in this field.