VNU-UET Repository: No conditions. Results ordered -Date Deposited. 2023-05-28T13:56:37ZEPrintshttp://eprints.uet.vnu.edu.vn/images/sitelogo.pnghttps://eprints.uet.vnu.edu.vn/eprints/2019-01-11T01:47:11Z2019-01-11T01:47:11Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3427This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/34272019-01-11T01:47:11ZNonlinear dynamic response of FGM porous plates on elastic foundation subjected to thermal and mechanical loads using the first order shear deformation theoryIn this paper, the first-order shear deformation theory is used to derive theoretical formulations illustrating the nonlinear dynamic response of functionally graded porous plates under thermal and mechanical loadings supported by Pasternak’s model of the elastic foundation. Two types of porosity including evenly distributed porosities (Porosity-I) and unevenly distributed porosities (Porosity-II) are assumed as effective properties of FGM plates such as Young’s modulus, the coefficient of thermal expansion, and density. The strain-displacement formulations using Von Karman geometrical nonlinearity and general Hooke’s law are used to obtain constitutive relations. Airy stress functions with full motion equations which is employed to shorten the number of governing equations along with the boundary and initial conditions lead to a system of differential equations of the nonlinear dynamic response of porous FGM plates. Considering linear parts of these equations, natural frequencies of porous FGM plates are determined. By employing Runge-Kutta method, the numerical results illustrate the influence of geometrical configurations, volume faction index, porosity, elastic foundations, and mechanical as well as thermal loads on the nonlinear dynamic response of the plates. Good agreements are obtained in comparison with other results in the literature.Dinh Duc Nguyenducnd@vnu.edu.vnDinh Quan VuDinh Nguyen Phamnguyenpd@vnu.edu.vnMinh Chien Trinh2019-01-07T02:22:05Z2019-01-07T02:22:05Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3374This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/33742019-01-07T02:22:05ZNumerical Similation and Testing of a Two-Body Heaving Wave Energy ConverterVan Ngoc PhungThe Mich NguyenThe Ba Dangbadt@vnu.edu.vnDinh Do Chu2019-01-07T02:21:00Z2019-01-07T02:21:00Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3372This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/33722019-01-07T02:21:00ZNumerical Analysis of a wave energy converter using linear generatorVan Ngoc PhungThe Mich NguyenThe Ba Dangbadt@vnu.edu.vnDinh Tuan Phan2019-01-02T03:25:02Z2019-01-02T03:25:02Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3371This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/33712019-01-02T03:25:02ZMột Phương Pháp Mới Để Xác Định Phân Bố Thấm/Chứa Cho Mô Hình Mô Phỏng Mỏ Móng Nứt NẻTheo một cách làm thông dụng hiện nay, phân bố thấm/chứa của mô hình mô phỏng vỉa được xác định qua hai bước rời rạc: Trong bước thứ nhất, một quan hệ hồi quy mạng thần kinh nhân tạo (ANN) giữa thấm/chứa với các thuộc tính địa chấn được xây dựng và sử dụng để thu nhận phân bố thấm/chứa cho toàn mỏ; Trong bước tiếp theo, phân bố thấm/chứa này được hiệu chỉnh dựa trên dữ liệu khai thác (phục hồi lịch sử). Tuy nhiên, với đối tượng móng nứt nẻ, dữ liệu thấm/chứa mẫu dọc giếng (dùng để xây dựng quan hệ ANN) không phải là dữ liệu đo trực tiếp nên quan hệ ANN mang tính xấp xỉ cao và cần được hiệu chỉnh. Thêm vào đó, đặc tính địa cơ học được mong đợi là có quan hệ với mức độ nứt nẻ của mỏ móng nứt nẻ, vì vậy, nên được bổ xung trong phân tích quan hệ ANN với thấm chứa.
Với các nhận xét nói trên, chúng tôi đã phát triển một phương pháp mới để xác định phân bố thấm / rỗng cho mỏ móng nứt nẻ. Trong phương pháp này, quan hệ ANN giữa độ thấm/rỗng với các thuộc tính địa chấn và thông số địa cơ học được xây dựng và sau đó được hiệu chỉnh dựa trên số liệu khai thác. Hiệu chỉnh quan hệ ANN được thực hiện bằng cách sử dụng thuật toán tối ưu để hiệu chỉnh các hệ số truyền trong mạng ANN nhằm giảm thiểu sai khác giữa đo đạc và tính toán.Phương pháp mới này đã được áp dụng thử nghiệm để xác định phân bố thấm cho mô hình mô phỏng khai thác móng Bạch Hổ. Kết quả thử nghiệm đã cho thấy những ưu điểm và khả năng áp dụng của phương pháp.The Duc NguyenNgoc Trung PhanThe Ba Dangbadt@vnu.edu.vn2019-01-02T03:23:59Z2019-01-02T03:23:59Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3369This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/33692019-01-02T03:23:59ZThe status and distribution of PCBs along the coast
of VietnamAbstract Polychlorinated biphenyls (PCBs), well-
known as an important scientiﬁc achievement, are now
considered as one of the most persistent organic
pollutants (POPs) that need to be strictly controlled
and forbidden worldwide (the Stockholm convention
on POPs). Vietnam is one of the countries that
encounters with serious issues from PCB contamina-
tion. This study presented a comprehensive review on
the status and contamination of PCBs along the coast
of Vietnam. The contaminated PCBs data in the water,
sediment and biological samples from 18 provinces
along Vietnam coastline were collected from various
sources. A comparison in PCBs contamination
between Vietnam and other Asian countries was
included. The status on PCBs contamination in
Vietnam since participated as a party of the Stockholm
convention on POPs in 2002 was also assessed. The
results showed that Vietnam is facing serious PCBs
contamination problems as it evidences the spread and
accumulation of PCBs in the marine environment. The
implementation of the Stockholm convention on POPs
(PCBs in particular) has not yet demonstrated signif-
icant effect on the reduction in PCBs contamination in
the environment. This information on PCBs contam-
ination in Vietnam urges government to strengthen the
mechanism, policy and legislation, the management
capacity for PCBs as well as applying advanced and
modern technologies in reducing, disposing and
eliminating PCBs from the environment.Thi Minh Hanh PhamThanh Nghi DuongDinh Lan TranVan Quan NguyenThe Ba Dangbadt@vnu.edu.vnHung Viet Pham2019-01-02T03:22:08Z2019-01-02T03:22:08Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3368This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/33682019-01-02T03:22:08ZKHẢO SÁT ẢNH HƯỞNG VẬN TỐC PHUN NHIÊN LIỆU TỚI TRƯỜNG NHIỆT ĐỘ TRONG LÒ NUNG GỐM SỬ DỤNG GASNgày nay, tại các làng nghề sản xuất gốm sứ ở nước ta chủ yếu sử dụng lò nung gốm sứ dạng nhiên liệu gas. Phương pháp thiết kế các lò nung này chủ yếu vẫn dựa trên tính toán thiết kế truyền thông, tức là tính toán dựa trên phương trình cân bằng nhiệt lượng, nhiệt trị của nhiên liệu, lượng nhiên liệu cần thiết cung cấp để lò đạt tới giá trị thiết kế. Các phương pháp trên không cho ta biết trước được phân bố trường nhiệt độ, áp suất, vận tốc dòng khí diễn ra trong lò. Từ những thực tế trên, bài báo cáo này có mục đích giới thiệu phương pháp mô phỏng số trường nhiệt độ lò nung gas bằng phần mềm mô phỏng số CFD, ANSYS Fluent. Các qui trình mô phỏng tính toán sô sẽ được giới thiệu cụ thể. Một vài kết quả mô phỏng ảnh hưởng của trường vận tốc tới trường phân bố nhiệt độ sẽ được trình bàyHoang Quan Nguyenquannh@vnu.edu.vnTien Dung Truong2019-01-02T03:19:58Z2019-01-02T03:19:58Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3367This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/33672019-01-02T03:19:58ZInvestigate magnetic field of dual Halbach array in linear generator using for wave energy conversionLinear permanent magnet machines have wide applications in various areas. In the wave energy conversion, the use of linear generator has earlier been regarded as difficult and uneconomical. Many attempts have been spent to overcome difficulties [15-17] however, for real field application, there are still many problems. In this study, an attempt to improve the magnetic flux density in linear generator has been investigated. A dual Halbach array structure is investigated on parameters of line generator in wave energy converter to enhance flux density in air gap, thus to improve output performance of linear machine. Numerical result from finite element method is employed to simulate and observe the flux distribution in the machine. The result also shows that the double Halbach array has increased magnetic flux density compared to the schema used in linear generator of Direct driven wave energy conversion.Huy Diep Dodohuydiep@gmail.comThe Ba Dangbadt@vnu.edu.vnVan Duc Nguyen2018-12-14T01:36:56Z2018-12-14T01:36:56Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3243This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/32432018-12-14T01:36:56ZNGHIÊN CỨU TÍCH HỢP MẠNG CẢM BIẾN KHÔNG DÂY DỰA TRÊN CÔNG NGHỆ ZIGBEE
INTEGRATED SENSORS NETWORK RESEARCH BASE ON ZIGBEE TECHNOLOGYHiện nay, trên thế giới có rất nhiều chuẩn không dây (wireless) để truyền dữ liệu với tốc độ cao giữa các thiết bị với nhau như BlueTooth hay Wifi. Nhưng đối với những mạng quản lý các cảm biến trong các ứng dụng điều khiển - tự động hóa của các thiết bị trong nhà hay bệnh viện thì Wifi hay BlueTooth lại không thể đáp ứng được. Chúng có nhiều khuyết điểm như sử dụng băng thông rộng làm tiêu hao nhiều điện năng không cần thiết, sử dụng các nguồn điện trực tiếp, ít sử dụng pin, phạm vi kết nối nhỏ hẹp, độ trễ cao, cơ chế bảo mật đơn giản (BlueTooth), yêu cầu về các thiết bị phần cứng cao, chi phí lớn. Nhờ chức năng điều khiển từ xa không dây, truyền dữ liệu ổn định, tiêu thụ năng lượng cực thấp, công nghệ mở đã giúp công nghệ ZigBee trở nên hấp dẫn sử dụng cho các ứng dụng mạng không dây
Trong nghiên cứu này, một mạng cảm biến không dây với công nghệ Zigbee ứng dụng trong nông nghiệp thông minh được tích hợp thử nghiệm với các đơn vị nhỏ nhất là các nút cảm biến có chức năng thu thập các thông số về môi trường, gửi đến trạm kiểm soát trung tâm và sau đó dữ liệu sẽ được gửi lên Database để quản lý và lưu trữ. Người dùng có thể theo dõi những thông số đó qua trang web hoặc điện thoại di động Android, từ đó đưa ra những quyết định phù hợp với cây trồng. Nhóm nghiên cứu đã thiết kế giao diện sao cho trực quan, dễ dàng sử dụng nhất để bất cứ ai cũng có thể tiếp cận được. Đây sẽ là một sản phẩm có thể được nhân rộng trên một vùng rộng lớn hoặc phạm vi tỉnh, thậm chí quốc gia, liên kết các vùng nông nghiệp trồng trọt lại với nhau, đưa nền nông nghiệp thông minh trở nên phổ biến và phát triển mạnh ở Việt Nam.Văn Hùng NguyễnNgọc Linh Nguyễnnlnguyen@vnu.edu.vn2018-12-13T02:51:55Z2018-12-13T02:51:55Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3229This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/32292018-12-13T02:51:55ZAnalytical approach to study nonlinear dynamic response and free vibration of laminated FG-CNTRC plates based on Reddy’s third-order laminated plate theoryThis work presents the nonlinear dynamic response and free vibration of laminated functionally graded
carbon nanotubes reinforced composite (FG-CNTRC) plates resting on elastic foundations. The laminated
nanocomposite plates are reinforced by single-walled carbon nanotubes (SWCNTs) that are assumed to be
uniformly distributed (UD) or functionally graded (FG) distributed along the thickness direction. The laminated
nanocomposite plates are made of various amorphous polymer matrices: Poly(methyl methacrylate) (PMMA) and
poly{(m-phenylenevinylene)-co-[(2,5-dioctoxy-p-phenylene) vinylene]} (PmPV). The nonlinear equations are
solved by both Galerkin method and Runge-Kutta method based on Reddy’s third-order laminated plate theory.
Detailed studies for the influences of various types of distribution and volume fractions of carbon nanotubes
(CNTs), geometrical parameters, Winkler and Pasternak elastic foundations on the nonlinear dynamic response and
natural frequencies and the number of layers and lamination angle of laminated FG-CNTRC plates are examined.Dinh Khoa NguyenDinh Nguyen Phamnguyenpd@vnu.edu.vn2018-12-13T02:51:08Z2018-12-13T02:51:08Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3226This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/32262018-12-13T02:51:08ZAn analytical study on nonlinear buckling and post-buckling of laminated FG-GPLRC cylindrical panels resting on elastic foundationsThe main purpose of this paper is to investigate the nonlinear buckling and post-buckling analysis of
laminated functionally graded graphene nanoplatelets reinforced composite (FG-GPLRC) cylindrical panels resting
on viscoelastic foundations in the thermal environment. The weight fraction of GPL nanofillers layer-wisely alters
across the thickness direction of panels. Using the rule of the mixture and the modified Halpin-Tsai model, material
properties of the laminated nanocomposite cylindrical panels are estimated. The basic equations are based on the
first-order shear deformation shell theory and solved by Galerkin method. Detailed results for the effect of the GPL
distribution pattern, weight fraction, and elastic foundation models on the buckling loads and load-deflection curves
of laminated FG-GPLRC cylindrical panels are studied.Dinh Duc Nguyenducnd@vnu.edu.vnHong Cong PhamDinh Nguyen Phamnguyenpd@vnu.edu.vn2018-12-12T15:19:56Z2018-12-12T15:19:56Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3225This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/32252018-12-12T15:19:56ZAnalysis of unsymmetric FGM sandwich beams based on a new third-order shear deformation theory in high-temperature environmentPlate, shell, and beam made by functionally graded materials are widely used and applied in a high-
temperature working environment so that studying the mechanical behaviors of these structures is useful for its
applications in real life. In this paper, we present new results of static bending in high temperature and thermal
buckling of sandwich FG beam based on new third-order shear deformation theory (TSDT) and finite element
formulations. In the case of static bending, we assume the sandwich beam placed in a high-temperature environment
for a long time, and so that temperature distribution is uniform across the beam thickness. In the case of thermal
buckling, we focus on temperature-dependent material properties solution (called the TD). Using this TSDT, the
analysis does not need any shear correction factors and has no shear-locking. The results show that not all FGMs
could process similar to mechanical behaviors and have the ability to perform at high temperature.Van Thom DoHoang Nam Nguyennamnh@hus.edu.vnVan Minh PhungTrung Thanh TranVan Chinh NguyenDinh Duc Nguyenducnd@vnu.edu.vn2018-12-12T15:19:07Z2018-12-12T15:19:07Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3224This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/32242018-12-12T15:19:07ZStatic bending and vibration analysis of two-layer composite plate based on first shear deformation theory using finite element methodA two-layer partial composite plate is a structure with outstanding advantages which can be widely applied
in many fields of engineering such as construction, transportation, mechanical, etc. However, there is no work in the
part to investigate this type of structure. This paper based on the first-order shear deformation plate theory (FSDT)
and finite element method (FEM) to develop a new four-node plate element with nine degrees of freedom per node
for static bending and vibration analysis of two-layer composite plate. The numerical results are compared with
published data for some special cases. The effects of some parametric such as boundary condition, stiffness of shear
connectors, height-to-width ratio are also performed to investigate.Van Vinh Phamvinhpv@gmail.comHoang Nam Nguyennamnh@hus.edu.vnVan Thom DoMinh Khoa NguyenDinh Duc Nguyenducnd@vnu.edu.vn2018-12-12T15:18:12Z2018-12-12T15:18:12Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3223This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/32232018-12-12T15:18:12ZAnalysis of linear elastic fracture mechanics for cracked functionally graded composites by enhanced local enriched consecutive-interpolation elementsThis paper reports the application of consecutive-interpolation procedure into four-node quadrilateral
elements for analysis of two-dimensional cracked solids made of functionally graded composites. Compared to
standard finite element method, the recently developed consecutive-interpolation has been shown to possess many
desirable features, such as higher accuracy and smooth nodal gradients it still satisfies the Kronecker-delta property
and keeps the total number of degrees of freedom unchanged. The discontinuity in displacement fields along the
crack faces and stress singularity around the crack tips are mathematically modeled using enrichment functions. The
Heaviside function is employed to describe displacement jump, while four branch functions being developed from
asymptotic stress fields are taken as basis functions to capture singularities. The interesting characteristic of
functionally graded composites is the spatial variation of material properties which are intentionally designed to be
served for particular purposes. Such variation has to be taken into account during the computation of Stress Intensity
Factors (SIFs). Performance of the proposed approach is demonstrated and verified through various numerical
examples, in which SIFs are compared with reference solutions derived from other methods available in the
literature.Dinh Du NguyenNgoc Minh NguyenQuoc Tinh BuiDinh Duc Nguyenducnd@vnu.edu.vn2018-12-12T15:17:25Z2018-12-12T15:17:25Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3222This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/32222018-12-12T15:17:25ZNonlinear vibration analyses of functionally graded moderate thick toroidal shell segment within Reddy’s third-order shear deformation shell theoryFunctionally graded material (FGM) is a modern composite material created from two components metal and
ceramic. The FGM is both highly heat-resistant like the ceramic and good resilience just like metal. Today, FGMs
have been used in several industries such as aviation, space, and nuclear power. The knowledge of the buckling,
post-buckling, and vibration of FGM structures plays an important role in the design of these structures. In this
study, the nonlinear vibration of functionally graded moderate thick toroidal shell segment surrounded by an elastic
foundation are investigated. Based on the Reddy’s third-order shear deformation shell theory with the geometrical
nonlinear in von Karman sense and Galerkin’s method, the governing equations are derived. The effects of
temperature, material, dimension geometry parameters and foundations on characteristics of nonlinear vibration as
natural frequencies, dynamic responses of shells are examined.Minh Vuong PhamDinh Duc Nguyenducnd@vnu.edu.vn2018-12-12T15:16:41Z2018-12-12T15:16:41Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3221This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/32212018-12-12T15:16:41ZBuckling analysis of cracked stiffened FGM plates by finite element methodFunctionally graded materials (FGMs) plate has the properties vary continuously in the thickness direction,
which has the cracks may be appeared, and the plate stiff reduce, easier to buckling, so that the studying of buckling
behaviors of this structure is useful. In this paper, the static buckling behaviors of cracked stiffened FGM plates are
studied by finite element method and phase-field theory based on the first order shear deformation theory. The
accuracy of this work is proved by comparing the results with respect to other studies. The effects of some
parameters of plate and stiffeners on static buckling are researched.Van Thom DoHoang Nam Nguyennamnh@hus.edu.vnHong Duc Doandoan.hd.amsl.eng@vnu.edu.vnMinh Khoa NguyenDinh Duc Nguyenducnd@vnu.edu.vn2018-12-12T15:15:27Z2018-12-12T15:15:27Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3220This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/32202018-12-12T15:15:27ZNonlinear dynamic analysis and vibration of shear deformable piezoelectric-FGM truncated conical shell resting on elastic foundations inthermal environmentsThis study investigates the nonlinear dynamic analysis and vibration of shear deformable FGM truncated
conical shell with piezoelectric actuators, resting on Pasternak type elastic foundations in thermal environments by
the analytical approach. Material properties are graded in the thickness direction according to a simple power law
distribution in terms of the fractions of constituents. The governing equations are based on the first-order shear
deformation theory (FSDT) with a von Karman-Donnell-type of kinematic nonlinearity. The Hamilton’s principle is
used to derive the equations of motion of piezoelectric FGM truncated conical shells. Those equations are solved by the Galerkin method and Runge-Kutta method. In numerical results, the effects of applied actuator voltage, temperature, dimensional parameters, semi-vertex angle, material properties and foundations on the nonlinear dynamic response and vibration of the piezoelectric FGM truncated conical shells are discussed in details.Dinh Duc Nguyenducnd@vnu.edu.vnQuoc Quan TranQuang Chan Do2018-12-12T15:12:23Z2018-12-12T15:12:23Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3218This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/32182018-12-12T15:12:23ZFree vibration analysis of functionally graded shells using an edge-based smoothed finite element methodAn edge-based smoothed finite element method (ES-FEM) combined with the mixed interpolation of tensorial components technique (MITC) for triangular elements (ESMITC3) for vibration analyses of functionally graded shells is investigated in this work. In the formulation of the ES-MITC3, the stiffness matrices are obtained by using the strain smoothing technique over the smoothing domains that formed by two adjacent MITC3 triangular shell elements sharing an edge. This strain smoothing technique can improve significantly the accuracy and
convergence of the original MITC3. The material properties of functionally graded shells are assumed to vary through the thickness direction by a power rule distribution of volume fractions of the constituents. The numerical examples demonstrated that the present ES-MITC3 method is free of shear locking and achieves the high accuracy compared to the exact solutions and others existing elements in the literature.Tien Dat PhamNam Hoang Nguyenhoangnn@vnu.edu.vnQuoc Hoa PhamVan Thom DoDinh Duc Nguyenducnd@vnu.edu.vn2018-12-12T15:10:25Z2018-12-12T15:10:25Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3228This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/32282018-12-12T15:10:25ZInvestigation on nonlinear dynamic response and free vibration of FG-CNTs reinforced composite truncated conical shells in the thermal environmentThe nonlinear dynamic response and free vibration of functionally graded carbon nanotubes (FG-CNTs)
reinforced composite truncated conical shells resting on elastic foundations in the thermal environment subjected to
axial load are carried out. The truncated conical shells are reinforced by single-walled carbon nanotubes (SWCNTs)
that are assumed to be uniformly distributed (UD) or functionally graded (FG) distributed along the thickness
direction. The nonlinear equations are solved by both Galerkin method and Runge-Kutta method based on the
classical shell theory with the geometrical nonlinear in von Karman and using the form of two-component deflection
function to solve the system of nonlinear partial differential equations. The material properties of FG-CNT
reinforced composite shells are assumed to be temperature-dependent. Detailed studies for the influences of various
types of distribution and volume fractions of carbon nanotubes, geometrical parameters, Winkler and Pasternak
elastic foundations on the nonlinear dynamic response and free vibration of FG-CNTRC truncated conical shells are
examined.Thi Thuy Anh Vuanhvutt@vnu.edu.vnDinh Nguyen Phamnguyenpd@vnu.edu.vn2018-11-26T06:01:00Z2018-11-26T06:01:00Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3136This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/31362018-11-26T06:01:00ZVibration and nonlinear dynamic response of eccentrically stiffened functionally graded composite truncated conical shells surrounded by an elastic medium in thermal environmentsA semi-analytical approach eccentrically stiffened functionally graded (ES-FGM) truncated conical shells surrounded by an elastic medium in thermal environments is presented. Based on the classical thin shell theory with the geometrical nonlinearity in von Karman Donnell sense, the smeared stiffeners technique and Galerkin method, this paper deals with vibration and nonlinear dynamic problem. The truncated conical shells are reinforced by ring stiffeners made of full metal or full ceramic depending on situation of stiffeners at the metal-rich or ceramic-rich side of the shell respectively. In addition, the study is not only assumed that the material properties depend on environment temperature variation, but also considered the thermal stresses in the stiffeners. Numerical results are given to evaluate effects of inhomogeneous, dimensional parameters, outside stiffeners, temperatures and elastic foundations to vibration and nonlinear dynamic response of structures.Quang Chan DoThi Thuy Anh Vuanhvutt@vnu.edu.vnDinh Duc Nguyenducnd@vnu.edu.vn2018-10-09T10:10:18Z2018-10-09T10:10:18Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3099This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/30992018-10-09T10:10:18ZNonlinear stability of shallow spherical FG-CNTRC shell using FSDTDinh Duc Nguyenducnd@vnu.edu.vnThi Thuy Anh Vuanhvutt@vnu.edu.vnVan Kiet Dinh2018-10-09T10:09:45Z2018-10-09T10:09:45Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3096This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/30962018-10-09T10:09:45ZFree vibration of cracked composite platesVan Thom DoHong Duc Doandoan.hd.amsl.eng@vnu.edu.vnDinh Duc Nguyenducnd@vnu.edu.vnTien Dat Pham2018-10-09T10:07:13Z2018-10-09T10:07:13Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3100This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/31002018-10-09T10:07:13ZBuckling analysis of FGM toroidal shell under torsional loadsDinh Duc Nguyenducnd@vnu.edu.vnMinh Vuong Pham2018-10-09T10:06:24Z2018-10-09T10:06:24Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3103This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/31032018-10-09T10:06:24ZA novel integration scheme for the consecutive-interpolation multilateral element to improve the stiffness matrixDinh Du NguyenDinh Duc Nguyenducnd@vnu.edu.vnQuoc Tinh Bui2018-10-09T10:00:44Z2018-10-09T10:00:44Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3102This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/31022018-10-09T10:00:44ZMechanical and thermal postbuckling of FG CNTRC thick circular cylindrical shells using higher-order shear deformation theoryDinh Duc Nguyenducnd@vnu.edu.vnThi Thiem Hoang2018-10-09T09:52:28Z2018-10-09T09:52:28Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3077This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/30772018-10-09T09:52:28ZNew approach to investigate nonlinear dynamic response of sandwich auxetic double curves shallow shells using TSDTNonlinear dynamic behavior of double curved shallow shells with negative Poisson’s ratios in auxetic honeycombs on elastic foundations subjected blast, mechanical and damping loads is investigated in the present article. This study considers double curved shallow shells with auxetic core which have three layers in which the top and the bottom outer skins are isotropic aluminum materials; the central layer has honeycomb structure using the same aluminum material. Based on the analytical solution, Reddy’s third order shear deformation theory (TSDT) with the geometrical nonlinear in von Karman and Airy stress functions method, Galerkin method and the fourth-order Runge-Kutta method, the resulting equations are solved to obtain expressions for nonlinear motion equations. The effects of geometrical parameters, material properties, elastic foundations, imperfections, blast loads, mechanical and damping loads on the nonlinear dynamic analysis of double curved shallow shells with negative Poisson’s ratios in auxetic honeycombs are studied.Hong Cong PhamDuy Khanh NguyenDinh Khoa NguyenDinh Duc Nguyenducnd@vnu.edu.vn2018-10-09T09:45:32Z2018-10-09T09:45:32Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3082This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/30822018-10-09T09:45:32ZAn analytical approach on nonlinear mechanical and thermal post-buckling of nanocomposite double-curved shallow shells reinforced by carbon nanotubesThis work presents the nonlinear mechanical and thermal post-buckling of nanocomposite double-curved shallow shells reinforced by single-walled carbon nanotubes resting on elastic foundations based on the higher order shear deformation theory with geometrical nonlinearity in von Karman–Donnell sense. The composite shells are made of various amorphous polymer matrices: poly(methyl methacrylate) (PMMA) and poly{(m-phenylenevinylene)-co-[(2,5-dioctoxy-p-phenylene) vinylene]} (PmPV). The governing equations are solved by the Galerkin method and Airy's stress function to achieve mechanical and thermal post-buckling behaviors of nanocomposite double-curved shallow shells. Various types of distributions of carbon nanotubes, both uniform distributions, and functionally graded distributions are examined. The material properties of nanocomposite double-curved shallow shells are assumed to be temperature dependent. Detailed parametric studies are carried out on the effect of various types of distribution and volume fractions of carbon nanotubes, temperature increments, elastic foundations, edge to radius and edge to thickness ratios on the nonlinear mechanical and thermal post-buckling of nanocomposite double-curved shallow shells reinforced by CNTs.Dinh Duc Nguyenducnd@vnu.edu.vnDinh Nguyen Phamnguyenpd@vnu.edu.vnHuy Cuong NguyenVan Sy NguyenDinh Khoa Nguyen2018-10-09T09:00:01Z2018-10-09T09:00:01Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3076This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/30762018-10-09T09:00:01ZNonlinear Dynamic Response of Functionally Graded Porous Plates on Elastic Foundation Subjected to Thermal and Mechanical LoadsIn this paper, the first-order shear deformation theory is used to derive theoretical formulations illustrating the nonlinear dynamic response of functionally graded porous plates under thermal and mechanical loadings supported by Pasternak’s model of the elastic foundation. Two types of porosity including evenly distributed porosities (Porosity-I) and unevenly distributed porosities (Porosity-II) are assumed as effective properties of FGM plates such as Young’s modulus, the coefficient of thermal expansion, and density. The strain-displacement formulations using Von Karman geometrical nonlinearity and general Hooke’s law are used to obtain constitutive relations. Airy stress functions with full motion equations which is employed to shorten the number of governing equations along with the boundary and initial conditions lead to a system of differential equations of the nonlinear dynamic response of porous FGM plates. Considering linear parts of these equations, natural frequencies of porous FGM plates are determined. By employing Runge-Kutta method, the numerical results illustrate the influence of geometrical configurations, volume faction index, porosity, elastic foundations, and mechanical as well as thermal loads on the nonlinear dynamic response of the plates. Good agreements are obtained in comparison with other results in the literature.Dinh Duc Nguyenducnd@vnu.edu.vnDinh Quang Vuquangvd2510@gmail.comDinh Nguyen PhamMinh Chien Trinh2018-10-09T08:59:16Z2018-10-09T08:59:16Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3075This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/30752018-10-09T08:59:16ZValidation simulation for free vibration and buckling of cracked Mindlin plates using phase-field methodThis article focus on validation phase-field method for simulation of free vibration and buckling of crack plates. The formula is derived from using Reissner-Mindlin plate theory. Validation simulation is carried out by numerically investigating free vibration and buckling of cracked plate with taking the configuration, material property, crack location, and other relevant assumptions as the same with the comparing references. The article shows that phase-field approach can be used to estimate the critical buckling load and frequencies of vibration mode. The article also demonstrates the significant advanced of phase-field method for plates with complex crack geometries.Hong Duc Doandoan.hd.amsl.eng@vnu.edu.vnVan Thom DoMinh Phuc PhanDinh Duc Nguyenducnd@vnu.edu.vn2018-10-09T08:57:38Z2018-10-09T08:57:38Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3074This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/30742018-10-09T08:57:38ZNonlinear buckling and post-buckling of FGM shear deformable truncated conical shells reinforced by FGM stiffenersQuang Chan DoDo Long VuDinh Duc Nguyenducnd@vnu.edu.vn2018-10-09T08:56:42Z2018-10-09T08:56:42Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3073This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/30732018-10-09T08:56:42ZNonlinear thermo-mechanical buckling and post-buckling response of porous FGM plates using Reddy’s HSDTThis work presents an analytical approach to investigate buckling and post-buckling behavior of FGM plate with porosities resting on elastic foundations and subjected to mechanical, thermal and thermomechanical loads. The formulations are based on Reddy's higher-order shear deformation plate theory taking into consideration Von Karman nonlinearity, initial geometrical imperfections, and Pasternak type of elastic foundations. By applying Galerkin method, closed-form relations of buckling loads and post-buckling equilibrium paths for simply supported plates are determined. Numerical results are carried out to show the effects of porosity distribution characteristics (Porosity-I and Porosity-II), geometrical parameters, material properties and elastic foundations on the mechanical, thermal and thermomechanical buckling loads and post-buckling resistance capacity of the porous FGM plates.Hong Cong PhamMinh Chien TrinhDinh Khoa NguyenDinh Duc Nguyenducnd@vnu.edu.vn2018-10-09T08:52:59Z2018-10-09T08:52:59Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3061This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/30612018-10-09T08:52:59ZA static buckling investigation of multi-cracked FGM plate based phase-field method coupling the new TSDTDinh Duc Nguyenducnd@vnu.edu.vnHong Duc DoanVan Thom DoDuc Truong Trinh2018-10-09T08:49:41Z2018-10-09T08:49:41Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3059This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/30592018-10-09T08:49:41ZVibration and nonlinear dynamic response of eccentrically stiffened functionally graded composite truncated conical shells in thermal environmentsQuang Chan DoThi Thuy Anh Vuanhvutt@vnu.edu.vnDinh Duc Nguyenducnd@vnu.edu.vn2018-10-09T08:46:16Z2018-10-09T08:47:00Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3068This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/30682018-10-09T08:46:16ZNonlinear Dynamic Response of Functionally Graded Porous
Plates on Elastic Foundation Subjected to Thermal and
Mechanical LoadsIn this paper, the first-order shear deformation theory is used to derive theoretical formulations
illustrating the nonlinear dynamic response of functionally graded porous plates under thermal and mechanical
loadings supported by Pasternak’s model of the elastic foundation. Two types of porosity including evenly
distributed porosities (Porosity-I) and unevenly distributed porosities (Porosity-II) are assumed as effective
properties of FGM plates such as Young’s modulus, the coefficient of thermal expansion, and density. The straindisplacement
formulations using Von Karman geometrical nonlinearity and general Hooke’s law are used to obtain
constitutive relations. Airy stress functions with full motion equations which is employed to shorten the number of
governing equations along with the boundary and initial conditions lead to a system of differential equations of the
nonlinear dynamic response of porous FGM plates. Considering linear parts of these equations, natural frequencies of porous FGM plates are determined. By employing Runge-Kutta method, the numerical results illustrate the influence of geometrical configurations, volume faction index, porosity, elastic foundations, and mechanical as well as thermal loads on the nonlinear dynamic response of the plates. Good agreements are obtained in comparison with other results in the literature.Dinh Duc Nguyenducnd@vnu.edu.vnDinh Quang Vuquangvd2510@gmail.comDinh Nguyen Phamnguyenpd@vnu.edu.vnMinh Chien Trinh2018-10-09T08:46:04Z2018-10-09T08:46:04Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3065This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/30652018-10-09T08:46:04ZGeometrically nonlinear dynamic response and vibration of shear deformable eccentrically stiffened FGM cylindrical panels subjected to thermal, mechanical and blast loadsBased on the first order shear deformation shell theory, this paper presents an analysis of the nonlinear dynamic response and vibration of imperfect eccentrically stiffened functionally graded material (ES-FGM) cylindrical panels subjected to mechanical, thermal, and blast loads resting on elastic foundations. The material properties are assumed to be temperature-dependent and graded in the thickness direction according to simple power-law distribution in terms of the volume fractions of the constituents. Both functionally graded material cylindrical panels and stiffeners having temperature-dependent properties are deformed under temperature, simultaneously. Numerical results for the dynamic response of the imperfect ES-FGM cylindrical panels with two cases of boundary conditions are obtained by the Galerkin method and fourth-order Runge–Kutta method. The results show the effects of geometrical parameters, material properties, imperfections, mechanical and blast loads, temperature, elastic foundations and boundary conditions on the nonlinear dynamic response of the imperfect ES-FGM cylindrical panels. The obtained numerical results are validated by comparing with other results reported in the open literature.Dinh Duc Nguyenducnd@vnu.edu.vnDuc Tuan NgoHong Cong PhamDinh Dat NgoDinh Khoa Nguyen2018-10-09T08:45:54Z2018-10-09T08:45:54Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3063This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/30632018-10-09T08:45:54ZNonlinear response and buckling analysis of eccentrically stiffened FGM toroidal shell segments in thermal environmentThis paper presents an analytical approach to study nonlinear response and buckling analysis of FGM toroidal shell segments reinforced by FGM stiffeners surrounded by elastic foundations in thermal environment and under external pressure. The formulations are based on Reddy's third-order shear deformation shell theory (TSDT) with von Karman nonlinearity, Pasternak type elastic foundations and smeared stiffener technique. By applying Galerkin's method and using stress function, closed-form expressions for determining the static critical external pressure load and postbuckling load–deflection curves are determined. Finally, the influences of geometrical parameters, volume fraction index, elastic foundations, and the effectiveness of stiffeners on the stability of shells are considered.Vuong Pham MinhDuc Nguyen Dinh2018-10-09T08:45:43Z2018-10-09T08:45:43Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3062This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/30622018-10-09T08:45:43ZInnovation practices at Vietnamese manufactures: the impacts of innovation on profitability and growthIn an effort of the Vietnamese government to improve the country's innovativeness, the Ministry of Science and Technology (MOST) carried out a research to investigate Vietnamese companies' current state of innovation. Data of 510 manufacturers used in this paper was extracted from the survey campaign by the MOST. Via statistical analysis, findings indicated that only a humble share of Vietnamese companies is currently performing innovative activities. These firms invest the most on new technology. When it comes to the relationship between innovative performance and firm performance, significant regressive relationships have been found yet, the results are dissimilar across industries. Besides, innovative performance displayed mixed effects on performance, which seems to confirm previous literatures' diverse receptions about this topic.Hoang Hoa Tronghoangtronghoa1988@gmail.comDung Pham Thedungpthe@gmail.comDuc Nguyen Dinhducnd@vnu.edu.vn2018-10-01T04:19:03Z2018-10-01T04:19:03Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3066This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/30662018-10-01T04:19:03ZThe stability of cracked rectangular plate with variable thickness using phase field methodThis study focuses on the investigation of the stability in a rectangular FGM plate with central crack. The plate thickness is changed linearly following the length of the plate. Using the Reissner-Mindlin first order shear deformation theory (FSDT), phase field theory and finite element method (FEM), the stability of fracture of the plate is determined. In order to ensure the reliability of the study, the obtained numerical results in this paper are compared with results reported in other publications. The work also presents the analysis of critical buckling computation for plate that have variation in thickness, the length of the crack on plate as well as the inclined angle of the crack. The numerical results show that the crack length impacts significantly to the critical buckling values of the plate, whereas the impact of inclined angle is less.Minh Phuc PhamVan Thom DoHong Duc Doandoan.hd.amsl.eng@vnu.edu.vnDinh Duc Nguyenducnd@vnu.edu.vn2018-10-01T03:59:43Z2018-10-01T03:59:43Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3064This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/30642018-10-01T03:59:43ZNew approach to investigate the nonlinear dynamic response and vibration of a functionally graded multilayer graphene nanocomposite plate on a viscoelastic Pasternak medium in a thermal environmentThis paper presents an analytical approach to investigate the nonlinear dynamic response and vibration of functionally graded multilayer nanocomposite plates reinforced with a low content of graphene platelets (GPLs) using first-order shear deformation theory and a stress function with full motion equations (not using Volmir’s assumptions). The weight fraction of GPL nanofillers is assumed to be constant in each individual GPL-reinforced composite (GPLRC). The modified Halpin–Tsai micromechanics model that takes into account the GPL geometry effect is adopted to estimate the effective Young’s modulus of the GPLRC layers. The plate is assumed to rest on a viscoelastic Pasternak medium and to be subjected to dynamic mechanical load in a thermal environment. Numerical results for the nonlinear dynamic response and vibration of functionally graded (FG) multilayer GPLRC plates are obtained by the Runge–Kutta method. The results show the influences of the GPL distribution pattern, weight fraction, geometry, foundation models, mechanical and temperature loads on the nonlinear dynamic response and vibration, natural frequencies and frequency–amplitude curves of FG multilayer GPLRC plates.Hong Cong PhamDinh Duc Nguyenducnd@vnu.edu.vn2018-08-27T01:35:30Z2018-08-27T01:35:30Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/3047This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/30472018-08-27T01:35:30ZStudy of the SPH Method for Simulation in LS-DYNAThe aim of this paper is to present the capabilities of Smoothed Particle Hydrodynamics (SPH) method in LS-DYNA. A new particle element has been added to LS-DYNA. It is based on Smoothed Particle Hydrodynamics theory. SPH is a meshless lagrangian numerical technique used to model the fluid equations of motion. SPH has proved to be useful in certain class of problems where large mesh distortions occur such as high velocity impact, crash simulations or compressible fluid dynamics. First, we introduce the basis principles of the SPH method. Then the coupling of this technique to LS-DYNA is presented and the input needed for such analysis is provided Two types of simulations have been comducted and show once again good capabilities of this new technology for both applicationsThanh Tung Trantranthanhtung@vnu.edu.vn2017-12-25T04:17:52Z2017-12-25T04:17:52Zhttp://eprints.uet.vnu.edu.vn/eprints/id/eprint/2842This item is in the repository with the URL: http://eprints.uet.vnu.edu.vn/eprints/id/eprint/28422017-12-25T04:17:52ZNew approach to investigate nonlinear dynamic response of
sandwich auxetic double curves shallow shells using TSDTNonlinear dynamic behavior of double curved shallow shells with negative Poisson’s ratios in auxetic honeycombs on elastic foundations subjected blast, mechanical and damping loads is investigated in the present article. This study considers double curved shallow shells with auxetic core which have three layers in which the
top and the bottom outer skins are isotropic aluminum materials; the central layer has honeycomb structure
using the same aluminum material. Based on the analytical solution, Reddy’s third order shear deformation
theory (TSDT) with the geometrical nonlinear in von Karman and Airy stress functions method, Galerkin method
and the fourth-order Runge-Kutta method, the resulting equations are solved to obtain expressions for nonlinear
motion equations. The effects of geometrical parameters, material properties, elastic foundations, imperfections,
blast loads, mechanical and damping loads on the nonlinear dynamic analysis of double curved shallow shells
with negative Poisson’s ratios in auxetic honeycombs are studied.Hong Cong PhamDuy Khanh NguyenDinh Khoa NguyenDinh Duc Nguyenducnd@vnu.edu.vn