Tran Ich Thinh

Finite element analysis of laminated composite plates using high order shear deformation theory

A rectangular non-conforming element based on Reddys higher-order shear deformation plate theory is developed. Although the plate theory is quite attractive but it could not be exploited as expected in finite-element analysis. This is due to the diculties associated with satisfaction of inter-elemental continuity requirement and satisfy zero shear stress boundary conditions of the plate theory. In this paper, the proposed element is developed where Reddys plate theory is successfully implemented. It has four nodes and each node contains 7 degrees of freedom. The performance of the element is tested with dierent numerical examples, which show its precision and range of applicability.

Analysis of stiffened laminated composite plates by finite element based on higher-order displacement theory

In this paper, authors use a fi nite element model based on higher-order displacement plate theory for analysis of stiffened laminated composite plates. Transverse shear deformation is included in the formulation making the model applicable for both moderately t hick and t hin composite plates. The plate element used is a nine-noded isoparametr ic one with nine degrees of freedom at each node. The stiffness of stiffener is reflected at a ll nine nodes of plate element in which it is placed. Accordingly, the stiffeners can be positioned anywhere within the place element. Free vibration and defl ection of stiffened laminated composite plates are carried out, and results are compared with existing analytical and other solutions.

Numerical analysis of free vibration of cross-ply thick laminated composite cylindrical shells by continuous element method

This paper presents the vibration analysis of thick laminated composite cylindrical shells by a new approach using the Continuous Element Method (CEM). Based on the analytical solutions for the differential equations of thick composite cylindrical shell taking into account shear deflection effects, the dynamic transfer matrix is built from which natural frequencies are easily calculated. A computer program is developed for performing numerical calculations and results from specific cases are presented. Numerical results of this work are compared with published analytical and Finite Element Method (FEM) results. Through different examples, advantages of CEM are confirmed: reduced size of model, higher precision, reduced time of computation and larger range of studied frequencies.

FREE VIBRATION OF THICK COMPOSITE PLATES ON NON-HOMOGENEOUS ELASTIC FOUNDATIONS BY DYNAMIC STIFFNESS METHOD

This research presents a new model for vibration analysis of thick laminated plates on a non-homogeneous elastic foundation by the Dynamic Stiffness Method (DSM). The non-homogeneous foundation consists of multi-segment Winkler-type and Pasternak-type elastic foundation. The Dynamic Stiffness Matrices using the First Shear Deformation Theory (FSDT) are constructed for cross-ply thick composite plates. A computer program is written using the present formulation for calculating natural frequencies and harmonic response of composite plates subjected to various types of boundary conditions. Numerical results are validated by comparison with available results in the literature and with Finite Element Method (FEM). Different test cases make evidence the advantages of the present model: higher precision, less data storage, less computing time and studied frequency range extended.

BUCKLING ANALYSIS OF LAMINATED CYLINDRICAL COMPOSITE SHELL PANEL UNDER MECHANICAL AND HYGROTHERMAL LOADS

This paper deals with buckling of analysis multilaminated cylindrical shell panels subjected to axial and hygrothermal loadings. The geometrical non-linear analysis is carried out using the Finite Element Method based on a single layer first shear deformation theory. A nine-nodal isoparametric element with 5 degrees of freedom per node is considered. The effects of different number of layers, lamination angles, length to width ratios and hygrothermal effects are studied.

Optimum problem of piezoelectric laminated composite plate using genetic algorithm

The finite element model based on First Shear Displacement Theory to study the mechanical and electrical behaviors of cantilever laminated composite plate bonded piezoelectric patches on surface is presented. A nine-node isoparametric rectangular element with 5 degrees of freedom for the generalized displacements and 2 electrical degrees of freedom at each node is used. Optimization techniques based on genetic algorithm (GAs) are applied in order to maximize the piezoelectric actuator efficiency, improve the structural performance. The illustrative examples and results of the appropriate applied voltages, position of bonded piezoelectric actuator patches.and fiber angle to achieve the desired displacement of the cantilever composite plate are presented.

Stress analysis of ceramic coatings under spherical indentation: Influence of a metallic interlayer

Spherical indentation problems of ceramic coatings/metallic interlayer/ductile substrate were investigated numerically by axisymmetric FEA for two typical ceramic coatings with relatively high and low elastic modulus deposited on aluminum alloy and carbon steel. Various indenter radius-coating thickness ratios and interlayer thickness-coating thickness ratios were used in the modeling. Radial stress distributions were discussed in connection with model parameters. The results showed that the suitable metallic interlayer could improve resistance of ceramic coating systems through reducing the peak tensile radial stress on the surface and interface of ceramic coatings.

Plastic damage evolution in multilayer coatings/ductile substrate system under spherical indentation: Influence of a metallic interlayer

SpheriGal indentation problems of ceramic coatings/metallic inter-layer/ductile substrate were investigated numerically by axisymmetric finite element analysis (FEA) for two typical ceramic coatings with relatively high and low elastic modulus deposited on aluminum alloy and carbon steel. Various indenter radius-coating thickness ratios and interlayer thickness-coating thickness ratios were used in the modeling. Plastic damage zone evolution were discussed in connection with model parameters. The results showed that the suitable metallic interlayer could improve resistance of ceramic coating systems through reducing the plastic damage zone size in the substrate under spherical indentation.

LOCKING PHENOMENA IN FINITE ELEMENT ANALYSIS OF DEEP BEAM.AND REMOVAL METHOD

Since earlier 30 years ago, Finite Element Methods (FEM) has become an indispensable tool of engineers for analysis mechanical behaviour of structures. Generally displacement models are used in most usual problems. Under certain material conditions, such elements may provide inaccurate results and exhibit slow convergence. Locking phenomena are the cause of these problems and this situation could limit the computation of many kinds of structures. This paper presents a deep beam element based upon mixed formulation, which may illuminate these locking phenomena.

Continuous element for vibration analysis of thick shells of revolution

This paper presents a new numerical method: Continous Element Method (CEM) for vibration analysis of thick shells of revolution taking into account the shear deflection effects. Natural frequencies and harmonic responses of cylindrical and conical shells subjected to different boundary conditions obtained with this kind of formulation are in close agreement with finite element solutions. The main advantage is the reduction of the size of the model thus allows the high precision in the results for a large frequency range.