Nguyen Thoi Trung

Static and free vibration analyses of laminated composite shells by cell-based smoothed discrete shear gap method (CS-DSG3) using three-node triangular elements

A cell-based smoothed discrete shear gap method (CS-DSG3) using three-node triangular elements was recently proposed to improve the performance of the discrete shear gap method (DSG3) for static and free vibration analyses of isotropic Reissner-Mindlin plates and shells. In this paper, the CS-DSG3 is further extended for static and free vibration analyses of laminated composite shells. In the present method, the first-order shear deformation theory (FSDT) is used in the formulation due to the simplicity and computational efficiency. The accuracy and reliability of the proposed method are verified by comparing its numerical solutions with those of others available numerical results.

A new energy indicator in damage locating vector method (DLV) for detecting multiple damaged positions in beam and truss structures

The paper presents a new indicator called normalized energy index (nei) in damage locating vector method (DLV) for detecting multiple damaged positions in beam and truss structures. In the DLV method, a set of load vectors, which is extracted from the change in flexibility matrix between an undamaged structure and a damaged one, is applied as static loads to the undamaged structure which are evaluated via the finite element modeling. Then, the nei values are computed for each element by using the displacements. In order to verify the accuracy and efficiency of a proposed indicator, a cantilevered beam and a 14-bay planar truss are considered.

A cell-based smoothed discrete shear gap method (CS-FEM-DSG3) for dynamic response of laminated composite plate subjected to blast loading

Abstract. The paper investigates the dynamic response of laminated composite plate under the effect of blast loading. The cell-based smoothed discrete shear gap method (CSFEM-DSG3) based on the first-order shear deformation theory (FSDT) and the equivalent layer theory (ELT) is used to model the behavior of the laminated composite plate. The blast loading is simulated by a time diagram of rectangular, triangular, exponential, or sinusoidal shape. The effects of the number of layers and fiber orientation to the displacement and stress fields of the laminated composite plate are discussed. Numerical results demonstrated the accuracy and reliability of the present method compared with previous published methods.

Applying the genetic algorithm and the consequential convex approximation programming for composite structure optimization

This paper applies the genetic algorithm and consequential convex approximation programming to deal with problems of minimizing the strain energy of a linear elastic fiber reinforced composite laminate in a state of plane stress. The directions of fibers are used as design variables. From the numerical results, an evaluation of two optimization techniques is performed.

About an approximate method to solve the static boundary value problems in the isotropic hardening elastic-plastic solid

The paper presents the theory, model, weak form, finite element method and return-mapping algorithm for the isotropic hardening elastic-plastic problem. Then applying the algorithm to numerically simulate a variety of plane strain problems.

About the edge-based smoothed finite element method for the Reissner-Mindlin plate-bending problem

The paper further develops the edge-based smoothed finite element method (ES-FEM) for analysis of Reissner Mindlin plates using triangular meshes . The bending and shearing stiffness matrices are obtained using strain smoothing technique over the smoothing domains associated with edges of elements. Transverse shear locking can be avoided with help of the discrete shear gap (DSG) method. The numerical examples show that the present ES-FEM-DSG method obtains ve.ry accurate results compared to the exact solution and other existing elements.

About applying directly the alpha finite element method (\(\alpha\)FEM) for solid mechanics using triangular and tetrahedral elements

An alpha finite element method (αFEM) has been recently proposed to compute nearly exact solution in strain energy for solid mechanics problems using three-node triangular (αFEM-T3) and four-node tetrahedral (αFEM-T4) elements. In the αFEM, a scale factor α ∈ [0, 1] is used to combine the standard fully compatible model of the FEM with a quasi-equilibrium model of the node-based smoothed FEM (NS-FEM). This novel combination of the FEM and NS-FEM makes the best use of the upper bound property of the NS-FEM and the lower bound property of the standard FEM. This paper concentrates on applying directly the αFEM for solid mechanics to obtain the very accurate solutions with a suitable computational cost by using α = 0.6 for 2D problems and α = 0.7 for 3D problems.