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Free vibration of tapered BFGM beams using an efficient shear deformable finite element model
Dinh Kien Nguyen,Thi Thom Tran 국제구조공학회 2018 Steel and Composite Structures, An International J Vol.29 No.3
An efficient and free of shear locking finite element model is developed and employed to study free vibration of tapered bidirectional functionally graded material (BFGM) beams. The beam material is assumed to be formed from four distinct constituent materials whose volume fraction continuously varies along the longitudinal and thickness directions by power-law functions. The finite element formulation based on the first-order shear deformation theory is derived by using hierarchical functions to interpolate the displacement field. In order to improve efficiency and accuracy of the formulation, the shear strain is constrained to constant and the exact variation of the cross-sectional profile is employed to compute the element stiffness and mass matrices. A comprehensive parametric study is carried out to highlight the influence of the material distribution, the taper and aspect ratios as well as the boundary conditions on the vibration characteristics. Numerical investigation reveals that the proposed model is efficient, and it is capable to evaluate the natural frequencies of BFGM beams by using a small number of the elements. It is also shown that the effect of the taper ratio on the fundamental frequency of the BFGM beams is significantly influenced by the boundary conditions. The present results are of benefit to optimum design of tapered FGM beam structures.
Dinh-Kien Nguyen,Buntara S. Gan,Thanh-Huong Trinh 국제구조공학회 2014 Structural Engineering and Mechanics, An Int'l Jou Vol.49 No.6
Geometrically nonlinear analysis of planar beam and frame structures made of functionally graded material (FGM) by using the finite element method is presented. The material property of the structures is assumed to be graded in the thickness direction by a power law distribution. A nonlinear beam element based on Bernoulli beam theory, taking the shift of the neutral axis position into account, is formulated in the context of the co-rotational formulation. The nonlinear equilibrium equations are solved by using the incremental/iterative procedure in a combination with the arc-length control method. Numerical examples show that the formulated element is capable to give accurate results by using just several elements. The influence of the material inhomogeneity in the geometrically nonlinear behavior of the FGM beam and frame structures is examined and highlighted.
Nguyen, Dinh-Kien,Gan, Buntara S.,Trinh, Thanh-Huong Techno-Press 2014 Structural Engineering and Mechanics, An Int'l Jou Vol.49 No.6
Geometrically nonlinear analysis of planar beam and frame structures made of functionally graded material (FGM) by using the finite element method is presented. The material property of the structures is assumed to be graded in the thickness direction by a power law distribution. A nonlinear beam element based on Bernoulli beam theory, taking the shift of the neutral axis position into account, is formulated in the context of the co-rotational formulation. The nonlinear equilibrium equations are solved by using the incremental/iterative procedure in a combination with the arc-length control method. Numerical examples show that the formulated element is capable to give accurate results by using just several elements. The influence of the material inhomogeneity in the geometrically nonlinear behavior of the FGM beam and frame structures is examined and highlighted.
Post-buckling responses of elastoplastic FGM beams on nonlinear elastic foundation
Thanh-Huong Trinh,Dinh-Kien Nguyen,Buntara S. Gan,S. Alexandrov 국제구조공학회 2016 Structural Engineering and Mechanics, An Int'l Jou Vol.58 No.3
The elastoplastic response of functionally graded material (FGM) beams resting on a nonlinear elastic foundation to an eccentric axial load is investigated by using the finite element method. The FGM is assumed to be formed from ceramic and metal phases with their volume fraction vary in the thickness direction by a power-law function. A bilinear elastoplastic behavior is assumed for the metallic phase, and the effective elastoplastic properties of the FGM are evaluated by Tamura-Tomota-Ozawa (TTO) model. Based on the classical beam theory, a nonlinear finite beam element taking the shift in the neutral axis position into account is formulated and employed in the investigation. An incremental-iterative procedure in combination with the arc-length control method is employed in computing the equilibrium paths of the beams. The validation of the formulated element is confirmed by comparing the equilibrium paths obtained by using the present element and the one available in the literature. The numerical results show that the elastoplastic post-buckling of the FGM beams is unstable, and the post-buckling strength is higher for the beams associated with a higher ceramic content. Different from homogeneous beams, yielding in the FGM beam occurs in the layer near the ceramic layer before in the layer near metal surface. A parametric study is carried out to highlight the effect of the material distribution, foundation support and eccentric ratio on the elastoplastic response of the beams.
Plane strain bending of a bimetallic sheet at large strains
Sergei E. Alexandrov,Nguyen D. Kien,Dinh V. Manh,Fedor V. Grechnikov 국제구조공학회 2016 Structural Engineering and Mechanics, An Int'l Jou Vol.58 No.4
This paper deals with the pure bending of incompressible elastic perfectly plastic two-layer sheets under plane strain conditions at large strains. Each layer is classified by its yield stress, shear modulus of elasticity and its initial percentage thickness in relation to the whole sheet. The solution found is semianalytic. In particular, a numerical technique is only necessary to solve transcendental equations. The general solution is cumbersome because different analytic expressions for the radial and circumferential stresses should be adopted in different regions of the whole sheet. In particular, there are several alternative ways a plastic region (or plastic regions) can propagate. However, for any given set of material and process parameters the solution to the problem consists of a sequence of rather simple analytic expressions connected by transcendental equations. The general solution is illustrated by a simple example.
Gan, Buntara S.,Trinh, Thanh-Huong,Le, Thi-Ha,Nguyen, Dinh-Kien Techno-Press 2015 Structural Engineering and Mechanics, An Int'l Jou Vol.53 No.5
This paper presents a finite element procedure for dynamic analysis of non-uniform Timoshenko beams made of axially Functionally Graded Material (FGM) under multiple moving point loads. The material properties are assumed to vary continuously in the longitudinal direction according to a predefined power law equation. A beam element, taking the effects of shear deformation and cross-sectional variation into account, is formulated by using exact polynomials derived from the governing differential equations of a uniform homogenous Timoshenko beam element. The dynamic responses of the beams are computed by using the implicit Newmark method. The numerical results show that the dynamic characteristics of the beams are greatly influenced by the number of moving point loads. The effects of the distance between the loads, material non-homogeneity, section profiles as well as aspect ratio on the dynamic responses of the beams are also investigated in detail and highlighted.
Buntara S. Gan,Thanh-Huong Trinh,Thi-Ha Le,Dinh-Kien Nguyen 국제구조공학회 2015 Structural Engineering and Mechanics, An Int'l Jou Vol.53 No.5
This paper presents a finite element procedure for dynamic analysis of non-uniform Timoshenko beams made of axially Functionally Graded Material (FGM) under multiple moving point loads. The material properties are assumed to vary continuously in the longitudinal direction according to a predefined power law equation. A beam element, taking the effects of shear deformation and cross-sectional variation into account, is formulated by using exact polynomials derived from the governing differential equations of a uniform homogenous Timoshenko beam element. The dynamic responses of the beams are computed by using the implicit Newmark method. The numerical results show that the dynamiccharacteristics of the beams are greatly influenced by the number of moving point loads. The effects of thedistance between the loads, material non-homogeneity, section profiles as well as aspect ratio on the dynamic responses of the beams are also investigated in detail and highlighted.
Cuong Manh Vu,Quang-Vu Bach,Huong Thi Vu,Dinh Duc Nguyen,Bui Xuan Kien,장순웅 한국고분자학회 2020 Macromolecular Research Vol.28 No.1
This paper presents an effective method for enhancing both the mode I (GIC) and mode II (GIIC) interlaminar fracture toughness of carbon fiber reinforced epoxy resin (CFRE). For precursor materials, silk fibroin nanofibers (nSF) and rice husk silica were prepared from sustainable resources. Nanocomposite samples were prepared using various loading ratios of the silica and nSF in epoxy resin (EP). Mechanical stirring and sonication techniques were used to prepare homogenous mixtures of silica and nSF in epoxy resin. Non-isothermal differential scanning calorimetry and the Kissinger equation were used to examine and calculate the cure kinetics and activation energy (Ea) of EP and the composite samples. The CFRE sample with hybrid fillers of nSF and silica at the ratio 0.2/20 (wt%/wt%) exhibited the highest GIC, and improved upon the mode-I and mode-II toughness of the pure-resin sample by 36.08% and 30.06%, respectively. Study of the fracture surfaces indicated that adding nSF and silica as fillers increases the energy required to fracture the CFRE.
Highly efficient adsorption of arsenite from aqueous by zirconia modified activated carbon
Pham Ngoc Chuc,Nguyen Quang Bac,Dao Thi Phuong Thao,Nguyen Trung Kien,Nguyen Thi Ha Chi,Nguyen Van Noi,Vo Thang Nguyen,Nguyen Thi Hong Bich,Dao Ngoc Nhiem,Dinh Quang Khieu 대한환경공학회 2024 Environmental Engineering Research Vol.29 No.2
Nguyen Van Hung,Bui Thi Minh Nguyet,Nguyen Huu Nghi,Nguyen Minh Luon,Nguyen Ngoc Bich,Le Van Thanh Son,Nguyen Trung Kien,Dao Ngoc Nhiem,Nguyen Thanh Tuoi,Dinh Quang Khieu 대한환경공학회 2024 Environmental Engineering Research Vol.29 No.4
In the present work, ZnO/g-C₃N₄/biochar was prepared, and it was used for visible-light driven photocatalytic degradation of some colorants (methylene blue, rhodamine B, methyl orange) and some antibiotics (doxycycline, ciprofloxacin, amoxicilline). Biochar was prepared by pyrolysing Phragmites australis biomass. The ZnO/g-C₃N₄/biochar composite was synthesized with the alkaline hydrolysis method. The obtained materials were characterized by X-ray diffraction, scanning electron microscopy, transition electron microscopy, energy dispersive X-ray/elemental mapping, ultraviolet-visible-diffuse reflectance spectroscopy, photoluminescence spectroscopy, nitrogen adsorption/desorption isotherms and X-ray photoelectron spectroscopy. The results show that ZnO nanoparticles with a large surface area are highly dispersed on the g-C₃N₄ particle surface and biochar. The composite exhibits superior photocatalytic degradation ability toward doxycycline, a broad-spectrum antibiotic of the tetracycline compared with individual components (ZnO or g-C₃N₄) and satisfies stability after six treatment cycles. The kinetics and degradation mechanisms of doxycyline were also addressed. In addition, the present catalyst also exhibits the photocatalytic degradation of methylene blue, rhodamine B, methyl orange, ciprofloxacin and amoxicillin in visible-light regions.