An Edge-based Smoothed Three-node Mindlin Plate Element (ES-MIN3) for Static and Free Vibration Analyses of Plates

T. Nguyen-Thoi,T. Bui-Xuan,P. Phung-Van,S. Nguyen-Hoang,H. Nguyen-Xuan 대한토목학회 2014 KSCE JOURNAL OF CIVIL ENGINEERING Vol.18 No.4

The edge-based strain smoothing technique is combined with the three-node Mindlin plate element (MIN3) to give a so-called theedge-based smoothed three-node Mindlin plate element (ES-MIN3) for static and free vibration analyses of plates. In the formulationof the ES-MIN3, the MIN3 together with a shear stabilized technique is used to compute the strains and to avoid the shear locking. Then the strain smoothing technique on the smoothing domains associated with edges of elements is used to smooth the strains on theadjacent elements. This strain smoothing technique can provide proper softening effect, which will effectively relieve the stiffbehavior of the MIN3 and thus improve significantly the accuracy of solutions. The numerical examples demonstrated that the ESMIN3is free of shear locking, passes the patch test and shows three superior properties such as: (1) be a strong competitor to othersexisting plate elements in the static analysis; (2) can give high accurate solutions in free vibration analysis; (3) can provide accuratelythe values of high frequencies of plates by using only coarse meshes.

An Edge-based Smoothed Finite Element Method (ES-FEM) for Dynamic Analysis of 2D Fluid-Solid Interaction Problems

T. Nguyen-Thoi,P. Phung-Van,V. Ho-Huu,L. Le-Anh 대한토목학회 2015 KSCE JOURNAL OF CIVIL ENGINEERING Vol.19 No.3

The paper presents an extension of the Edge-based Smoothed Finite Element Method (ES-FEM-T3) using triangular elements forthe dynamic response analysis of two-dimension fluid-solid interaction problems based on the pressure-displacement formulation. Inthe proposed method, both the displacement in the solid domain and the pressure in the fluid domain are smoothed by the gradientsmoothing technique based on the smoothing domains associated with the edges of the triangular elements. Thanks to the softeningeffect of the gradient smoothing technique used in the ES-FEM-T3, the numerical solutions for the coupled systems by the ES-FEMT3are improved significantly compared to those by some other existing FEM methods.

Reduction of cement consumption by producing smart green concretes with natural zeolites

Nguyen Thoi Trung,Nima Alemi,James H. Haido,Mahdi Shariati,Seyedata Baradaran,Salim T. Yousif 국제구조공학회 2019 Smart Structures and Systems, An International Jou Vol.24 No.3

This study was carried out to evaluate the natural zeolite in producing green concrete as an effort to prevent global warming and environmental impact problems of cement industries. To achieve this target, two types of natural zeolites applied to study physical, chemical and compressive strength of concrete containing different percentages of zeolites. The results in comparison with control samples indicate that compressive strength of zeolites mixes increases with the 15% replacement of zeolite instead of cement in all types of samples. In the water-cement ratio of 0.6, results showed an increase in the compressive strength of all percentages of replacement. This results indicate that using natural zeolites could be produced a green concrete by a huge reduction and saving in the consumption of cement.

Static response and free vibration of functionally graded carbon nanotube-reinforced composite rectangular plates resting on Winkler–Pasternak elastic foundations

Duc, Nguyen Dinh,Lee, Jaehong,Nguyen-Thoi, T.,Thang, Pham Toan Elsevier 2017 AEROSPACE SCIENCE AND TECHNOLOGY Vol.68 No.-

<P><B>Abstract</B></P> <P>In the present article, static response and free vibration of functionally graded carbon nanotube reinforced composite (FG-CNTRC) rectangular plate resting on Winkler–Pasternak elastic foundations using an analytical approach are studied. The rectangular plates are reinforced by single-walled carbon nanotubes (SWCNTs) which are assumed to be graded through the thickness direction with four types of distributions. The mathematical model of the FG-CNTRC plate is developed based on the first-order shear deformation plate theory (FSDT) and Hamilton principle. By using Navier solution, the governing equations are solved to obtain the central deflection and the natural frequency parameters. Several examples are verified to have higher accuracy than those from the previous method in the literature. Also, the effects of different parameters on static response and natural frequency of FG-CNTRC plate are highlighted by solving numerous examples. Finally, these new results may serve as benchmarks for future investigations.</P>

An efficient procedure for lightweight optimal design of composite laminated beams

V. Ho-Huu,T. Vo-Duy,D. Duong-Gia,T. Nguyen-Thoi 국제구조공학회 2018 Steel and Composite Structures, An International J Vol.27 No.3

A simple and efficient numerical optimization approach for the lightweight optimal design of composite laminated beams is presented in this paper. The proposed procedure is a combination between the finite element method (FEM) and a global optimization algorithm developed recently, namely Jaya. In the present procedure, the advantages of FEM and Jaya are exploited, where FEM is used to analyze the behavior of beam, and Jaya is modified and applied to solve formed optimization problems. In the optimization problems, the objective aims to minimize the overall weight of beam; and fiber volume fractions, thicknesses and fiber orientation angles of layers are selected as design variables. The constraints include the restriction on the first fundamental frequency and the boundaries of design variables. Several numerical examples with different design scenarios are executed. The influence of the design variable types and the boundary conditions of beam on the optimal results is investigated. Moreover, the performance of Jaya is compared with that of the well-known methods, viz. differential evolution (DE), genetic algorithm (GA), and particle swarm optimization (PSO). The obtained results reveal that the proposed approach is efficient and provides better solutions than those acquired by the compared methods.

Closed-form expression for nonlinear analysis of imperfect sigmoid-FGM plates with variable thickness resting on elastic medium

Thang, Pham-Toan,Nguyen-Thoi, T.,Lee, Jaehong Elsevier 2016 COMPOSITE STRUCTURES -BARKING THEN OXFORD- Vol.143 No.-

<P><B>Abstract</B></P> <P>With the aim of reducing the weight of structures, functionally graded materials (FGM) plates with variable thickness have been widely used in various engineering applications such as aeronautical, mechanical and ocean structures. However so far, the analytical approaches for analyzing the instability behaviors of FGM plates with variable thickness are still somehow limited in the literature. The paper hence presents an analytical approach to investigate the influences of variable thickness on buckling and postbuckling behavior of imperfect sigmoid FGM (S-FGM) plates resting on elastic medium subjected to compressive loading. The material properties of S-FGM plates are assumed to be graded in the thickness direction according to a simple power law distribution in terms of the volume fractions of the constituents. Governing equations are based on the classical plate theory with von Karman-type geometric nonlinearity. The initial geometrical imperfections of plates are also accounted. By using the Galerkin procedure and the Airy stress function, the resulting equations are solved to obtain the closed form expressions for nonlinear equilibrium paths. The effects of power-law indices, coefficients of foundation, initial geometrical imperfections and geometrical parameters on nonlinear stability of plates are comprehensively investigated. The results reveal that the variable thickness of plate has a significant effect on the buckling behavior of S-FGM plates under compression loading.</P>

Elastic buckling and free vibration analyses of porous-cellular plates with uniform and non-uniform porosity distributions

Thang, Pham Toan,Nguyen-Thoi, T.,Lee, Dongkyu,Kang, Joowon,Lee, Jaehong Elsevier 2018 Aerospace science and technology Vol.79 No.-

<P><B>Abstract</B></P> <P>The aim of this research paper is to present the elastic buckling and free vibration analyses of porous-cellular plates based on the first-order shear deformation theory (FSDT). In the porous-cellular plate model, porosities are dispersed by uniform and non-uniform (symmetric and asymmetric) distribution patterns. The material properties, such as Young's modulus and mass density of the porous-cellular plates are assumed to vary along the thickness direction in term of porosity coefficient. First, the dynamic version of Hamilton's principle is applied to derive the Euler–Lagrange equations. Then, in the case of simply supported boundary condition, the critical buckling load and natural frequency of the porous-cellular plates are obtained using the Navier procedure. Furthermore, the reliability of the current formulation is validated by several examples. Finally, a comprehensive examination into the influence of porosity coefficient, porosity distributions, and the geometric parameters on the buckling behavior and vibration response of the porous-cellular plates are performed. Numerical results indicate that the effect of porosity distributions on the structural performance and provide the useful insights into the porosity design to achieve appropriately natural frequency and buckling resistance.</P>

A non-ordinary state-based peridynamics formulation for thermoplastic fracture

Amani, J.,Oterkus, E.,Areias, P.,Zi, G.,Nguyen-Thoi, T.,Rabczuk, T. Pergamon Press ; Elsevier Science Ltd 2016 International journal of impact engineering Vol.87 No.-

In this study, a three-dimensional (3D) non-ordinary state-based peridynamics (NOSB-PD) formulation for thermomechanical brittle and ductile fracture is presented. The Johnson-Cook (JC) constitutive and damage model is used to taken into account plastic hardening, thermal softening and fracture. The formulation is validated by considering two benchmark examples: 1) The Taylor-bar impact and 2) the Kalthoff-Winkler tests. The results show good agreements between the numerical simulations and the experimental results.

Identification of the most influencing parameters on the properties of corroded concrete beams using an Adaptive Neuro-Fuzzy Inference System (ANFIS)

Mahdi Shariati,Mohammad Saeed Mafipour,James H. Haido,Salim T. Yousif,Ali Toghroli,Nguyen Thoi Trung,Ali Shariati 국제구조공학회 2020 Steel and Composite Structures, An International J Vol.34 No.1

Different parameters potentially affect the properties of corroded reinforced concrete beams. However, the high number of these parameters and their dependence cause that the effectiveness of the parameters could not be simply identified. In this study, an adaptive neuro-fuzzy inference system (ANFIS) was employed to determine the most influencing parameters on the properties of the corrosion-damaged reinforced concrete beams. 207 ANFIS models were developed to analyze the collected data from 107 reinforced concrete (RC) beams. The impact of 23 input parameters on nine output factors was investigated. The results of the paper showed the order of influence of each input parameter on the outputs and revealed that the input parameters regarding the uncorroded properties of concrete beams are the most influencing factors on the corresponding corroded properties of the beams.