T. Vo-Duy
Ton Duc Thang University
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Publication
Featured researches published by T. Vo-Duy.
Applied Mathematics and Computation | 2015
N. Nguyen-Minh; T. Nguyen-Thoi; T. Bui-Xuan; T. Vo-Duy
CS-FEM-DSG3 is extended for static and free vibration analyses of stiffened folded plates.Original CS-FEM-DSG3 is combined with an Allmans plane stress triangular element and stiffened by Timoshenko beam element.Stiffeners can be placed anywhere on the plate and need not be placed along the mesh lines. Recently, a cell-based smoothed discrete shear gap method (CS-FEM-DSG3) based on the first-order shear deformation theory (FSDT) was proposed for static and free vibration analyses of Mindlin plates. The CS-FEM-DSG3 uses three-node triangular elements that can be easily generated automatically for arbitrary complicated geometric domains. In this paper, the CS-FEM-DSG3 is further extended for static and free vibration analyses of stiffened folded plates, by combining the original CS-FEM-DSG3 with an Allmans plane stress triangular element and with a stiffener modeled by Timoshenko beam element. The model of a stiffened folded plate is formed by (1) regarding the plate and the stiffener separately in which the stiffeners can be placed anywhere on the plate and need not be placed along the mesh lines, (2) imposing displacement compatible conditions between the plate and the stiffener so that displacement fields of the stiffener can be expressed in terms of the mid-surface displacement of the plate, (3) superimposing the strain energy of plate and stiffener, and (4) using a transformation of degrees of freedom from a local system to a global system. The accuracy and reliability of the proposed method are verified by comparing its numerical solutions with those of other available numerical methods.
Neural Computing and Applications | 2018
V. Ho-Huu; T. Nguyen-Thoi; T. Truong-Khac; L. Le-Anh; T. Vo-Duy
Structural optimization with frequency constraints is well known as a highly nonlinear and complex optimization problem with many local optimum solutions. Therefore, to solve such problems effectively, designers need to use adequate optimization methods which can make a good balance between the computational cost and the quality of solutions. In this work, a novel differential evolution (DE) is proposed to solve the shape and size optimization problems for truss structures with frequency constraints. The proposed method, called ReDE, is a new version of the DE algorithm with two improvements. Firstly, the roulette wheel selection is employed to choose members for the mutation phase instead of random selection as in the conventional DE. Secondly, an elitist selection technique is applied to the selection phase instead of basic selection to improve the convergence speed of the method. The efficiency and reliability of the proposed method are demonstrated through five numerical examples. Numerical results reveal that the proposed algorithm outperforms many optimization methods in the literature.
International Journal of Computational Methods | 2017
T. Nguyen-Thoi; Timon Rabczuk; V. Ho-Huu; L. Le-Anh; H. Dang-Trung; T. Vo-Duy
A cell-based smoothed three-node Mindlin plate element (CS-MIN3) was recently proposed and proven to be robust for static and free vibration analyses of Mindlin plates. The method improves significantly the accuracy of the solution due to softening effect of the cell-based strain smoothing technique. In addition, it is very flexible to apply for arbitrary complicated geometric domains due to using only three-node triangular elements which can be easily generated automatically. However so far, the CS-MIN3 has been only developed for isotropic material and for analyzing intact structures without possessing internal cracks. The paper hence tries to extend the CS-MIN3 by integrating itself with functionally graded material (FGM) and enriched functions of the extended finite element method (XFEM) to give a so-called extended cell-based smoothed three-node Mindlin plate (XCS-MIN3) for free vibration analysis of cracked FGM plates. Three numerical examples with different conditions are solved and compared with previous published results to illustrate the accuracy and reliability of the XCS-MIN3 for free vibration analysis of cracked FGM plates.
International Journal of Computational Methods | 2015
T. Nguyen-Thoi; M. H. Nguyen-Thoi; T. Vo-Duy; N. Nguyen-Minh
The paper presents the formulation and recent development of the cell-based smoothed discrete shear gap plate element (CS-FEM-DSG3) using three-node triangles. In the CS-FEM-DSG3, each triangular element will be divided into three sub-triangles, and in each sub-triangle, the original plate element DSG3 is used to compute the strains and to avoid the transverse shear locking. Then the cell-based strain smoothing technique (CS-FEM) is used to smooth the strains on these three sub-triangles. The numerical examples illustrate four superior properties of the CS-FEM-DSG3 including: (1) being a strong competitor to many existing three-node triangular plate elements in the static analysis; (2) giving high accurate solutions for problems with skew geometries in the static analysis; (3) giving high accurate solutions in free vibration analysis; (4) providing accurate values of high frequencies of plates by using only coarse meshes. Due to its superior and simple properties, the CS-FEM-DSG3 has been now developed for various analyses such as: flat shells, stiffened plates, functionally graded plates, composite plates, piezoelectricity composite plates, cracked plate and plates resting on the viscoelastic foundation subjected to moving loads, etc.
Advances in Engineering Software | 2017
D. Dinh-Cong; T. Vo-Duy; V. Ho-Huu; H. Dang-Trung; T. Nguyen-Thoi
Abstract The paper presents an efficient multi-stage optimization approach for damage detection in plate-like structures. In this approach, the damage identification process is achieved by minimizing an objective function established via flexibility changes of the structure. The vector of design variables represents correspondingly the damage extent of elements discretized by the finite element model. For analyzing the response of plate structures, the finite element model using 9-node quadratic quadrilateral elements is applied. For solving the optimization problem, a modified differential evolution (MDE) algorithm, which can help enhance the balance of global and local searches in each generation, is used for many stages of damage detection, in which the low damage variables in each stage are gradually eliminated after several generations to reduce the dimension of searching space and to increase the convergence rate of the problem. The efficiency of the proposed method is investigated through two numerical examples for isotropic and laminated composite plates. The obtained results indicate that the proposed method not only successfully detects the location and severity of multi-damage cases in the plate structures, but also show the better efficiency in term of computational cost.
Advances in Structural Engineering | 2017
D. Dinh-Cong; T. Vo-Duy; N. Nguyen-Minh; V. Ho-Huu; T. Nguyen-Thoi
This article proposes a two-stage damage identification method to identify the location and extent of multiple damages at individual layers in laminated composite beams. In the first stage, the damage locating vector method using normalized cumulative energy is employed to detect the locations of suspected damaged elements. In the second stage, the degree of the suspected damaged elements is determined by solving an optimization problem via differential evolution algorithm. To identify damage at a specific layer of the laminated composite beams, the layerwise theory is applied to analysis behavior of the beams. The performance of the method is assessed through two numerical examples with different damage scenarios. In addition, the effect of noise on the damage identification results is investigated.
Journal of Statistical Computation and Simulation | 2017
Tai Vovan; T. Nguyen-Thoi; T. Vo-Duy; V. Ho-Huu; Thao Nguyen-Trang
ABSTRACT This article modifies two internal validity measures and applies them to evaluate the quality of clustering for probability density functions (pdfs). Based on these measures, we propose a new modified genetic algorithm called GA-CDF to establish the suitable clusters for pdfs. The proposed algorithm is tested by four numerical examples including two synthetic data sets and two real data sets. These examples illustrate the superiority of proposed algorithm over some existing algorithms in evaluating the internal or external validity measures. It demonstrates the feasibility and applicability of the GA-CDF for practical problems in data mining.
Journal of Composite Materials | 2018
T. Vo-Duy; T. Truong-Thi; V. Ho-Huu; T. Nguyen-Thoi
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.
Expert Systems With Applications | 2018
V. Ho-Huu; D. Duong-Gia; T. Vo-Duy; T. Le-Duc; T. Nguyen-Thoi
Abstract Over the past decades, the reliability-based design optimization of truss structures has been still a major challenge for engineering designers and even for researchers because of its complexities and high computational cost. In this paper, a new approach based on a novel combination of multi-objective evolutionary optimization and reliability analysis is proposed to deal with such kinds of problems. The proposed method consists of two separate steps. First, a multi-objective design optimization problem is formulated and solved by a multi-objective evolutionary optimization algorithm. Secondly, reliability analysis problems are formed by taking into account the uncertainty of input data of the problem, and a reliability analysis method is used to evaluate the reliability of all solutions obtained at the first step. Based on the obtained reliability, the suitable optimal solutions with a certain level of reliability can be readily identified. The proposed approach has some advantages such as: 1) it can give a set of many optimal solutions with different levels of reliability by only one run; 2) it can easily handle the design optimization problems of truss structures with continuous, discrete or mixed continuous-discrete design variables; 3) it is quite simple for engineering designers to understand and implement. To demonstrate the efficiency and applicability of the proposed method, three examples of truss structures are carried out, and the obtained results are compared to those available in the literature. The acquired results reveal that the proposed approach is reliable and more competitive compared to other methods.
Applied Soft Computing | 2018
D. Dinh-Cong; T. Vo-Duy; T. Nguyen-Thoi
Abstract The paper proposes a practical two-stage approach for damage assessment in truss structures using noisy modal data collected from a limited number of sensors. In the first stage, a newly developed damage indicator, named here as normalized modal strain energy based damage index (nMSEBI), is proposed to locate effectively potential damage elements. In the second stage, the teaching-learning-based optimization (TLBO) algorithm is utilized as a robust optimization solver to determine the damage severity of suspected damage sites and also to exclude false alarms (if any) obtained in the previous stage. In addition, a Neumann series expansion-based second-order model reduction method (NSEMR-II) is adopted to condense the structural physical properties due to a limited number of sensors placed on the structure. The robustness and effectiveness of the proposed two-stage damage identification method are verified through two specific structures including a 31-bar planar truss and a 52-bar space truss with various damage scenarios. The obtained results clearly indicate that the proposed method can work well in determining both damage location and damage severity in the truss structures.