• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.8
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• pp.2123-2138
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• 1994

A study on the dynamic mechanical properties of the high strength carbon fiber epoxy composite beam was carried out. The macromechanical model was used for the theoretical analysis of the symmetric laminated composite beam. The anisotropic plate theory and Bernoulli-Euler beam theory were used to predict the effective flexural elastic modulus and the specific damping capacity of laminated composite beam. The free flexural vibration and torsional vibration tests were carried out to determine the specific damping capacities of the unidirectional laminated composite beam. The vibration tests were performed in a vacuum chamber with laser vibrometer system and electromagnetic hammer to obtain accurate experimental data. From the computational and experimental results, it was found that the theoretical values with the macromechanical analysis and the experimental data of symmetric laminated composite beam were in good agreement.

• Steel and Composite Structures
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• v.18 no.3
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• pp.583-601
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• 2015

In the present study, the combined effects of thermal and mechanical loadings on the interlaminar shear stresses of both moderately thin and thick composite laminated beams are numerically analyzed. The finite element modelling of laminated composite beams and analysis of interlaminar stresses are performed using the commercially available software package MSC NASTRAN/PATRAN. The validity of the finite element analysis (FEA) is demonstrated by comparing the experimental test results obtained due to mechanical loadings under the influence of thermal environment with those derived using the present FEA. Various parametric studies are also performed to investigate the effect of thermal loading on interlaminar stresses generated in symmetric, anti-symmetric, asymmetric, unidirectional, cross-ply, and balanced composite laminated beams of different stacking sequences with identical mechanical loadings and various boundary conditions. It is shown that the elevated thermal environment lead to higher interlaminar shear stresses varying with the stacking sequence, length to thickness ratio, ply orientations under identical mechanical loading and boundary conditions of the composite laminated beams. It is realized that the magnitude of the interlaminar stresses along xz plane is always much higher than those of along yz plane irrespective of the ply-orientation, length to thickness ratios and boundary conditions of the composite laminated beams. It is also observed that the effect of thermal environment on the interlaminar shear stresses in carbon-epoxy fiber reinforced composite laminated beams are increasing in the order of symmetric cross-ply laminate, unidirectional laminate, asymmetric cross-ply laminate and anti-symmetric laminate. The interlaminar shear stresses are higher in thinner composite laminated beams compared to that in thicker composite laminated beams under all environmental temperatures irrespective of the laminate stacking sequence, ply-orientation and boundary conditions.

• Steel and Composite Structures
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• v.3 no.6
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• pp.439-450
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• 2003

The finite strip transition matrix technique, a semi analytical method, is employed to obtain the buckling loads and the natural frequencies of symmetric cross-ply laminated composite plates with edges elastically restrained against both translation and rotation. To illustrate the accuracy and the validation of the method several example of cross play laminated composite plates were analyzed. The buckling loads and the frequency parameters are presented and compared with available results in the literature. The convergence study and the excellent agreement with known results show the reliability of the purposed technique.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.7 s.94
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• pp.1761-1771
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• 1993

In this paper, the design of thick laminated composite plate subjected to thermal buckling load under uniform temperature distribution is presented. In the design procedures of composite laminated plates for maximum thermal buckling load. the finite element method based on shear deformed theory is used for the analysis or laminated plates. One-demensional search method is used to find optimal fiber orientation and, in the next step, optimal thickness is investigated. Design variables such as fiber orientation and ply thicknesses coefficient of plates are adopted. The optimal design for the symmetric or antisymmetric laminated plates consisted of 4 layers with maximum thermal buckling load is performed.

• Structural Engineering and Mechanics
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• v.72 no.6
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• pp.763-774
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• 2019

The main aim of this paper is enhancing design of traditional laminated composite plates subjected to static loads. In this regard, this paper suggests embedding a lightweight porous layer in the middle of laminated composite as the core layer of the resulted sandwich plate. The static responses of the suggested structures with uniform, symmetric and non-symmetric porosity distributions are compared to optimize their design. Using the first order shear deformation theories, the static governing equations of the suggested laminated composite plates with a porous layer (LCPPL) rested on two-parameter foundation are obtained. A finite element method is also utilized to solve the governing equations of LCPPLs. Effects of laminated composite and porosity characteristics as well as geometry dimension, edges' boundary conditions and foundation coefficients on the static deflection and stress distribution of the suggested composite plates have been investigated. The results reveal that the use of core between the layers of laminated composites leads to a sharp reduction in the static deflections of LCPPLs. Furthermore, in compare with perfect cores, the use of porous core between the layers of laminated composite plates can offer a considerable reduction in structural weight without a significant difference in their static responses.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.14 no.2
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• pp.67-78
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• 2010

An elastic field composed of symmetric cross-ply laminated material is analyzed in roller guided panel. The plane stress elasticity problem is formulated in terms of two displacement parameters with mixed boundary conditions. The numerical solution for two displacement parameters is obtained using a finite element method considering a panel of glass/epoxy laminated composite. Some components of stress and displacement at different sections of panel are displayed. The results makes sure that the formulation developed in this study can be applied to analyze the characteristics of elastic field made of laminated composite under any boundary conditions.

• Structural Engineering and Mechanics
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• v.14 no.3
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• pp.245-262
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• 2002

The free vibration analysis of stiffened laminated composite plates has been performed using the layered (zigzag) finite element method based on the first order shear deformation theory. The layers of the laminated plate is modeled using nine-node isoparametric degenerated flat shell element. The stiffeners are modeled as three-node isoparametric beam elements based on Timoshenko beam theory. Bilinear in-plane displacement constraints are used to maintain the inter-layer continuity. A special lumping technique is used in deriving the lumped mass matrices. The natural frequencies are extracted using the subspace iteration method. Numerical results are presented for unstiffened laminated plates, stiffened isotropic plates, stiffened symmetric angle-ply laminates, stiffened skew-symmetric angle-ply laminates and stiffened skew-symmetric cross-ply laminates. The effects of fiber orientations (ply angles), number of layers, stiffener depths and degrees of orthotropy are examined.

• Journal of Korean Society of Steel Construction
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• v.11 no.2 s.39
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• pp.117-129
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• 1999

The objective of this study is to identify the advantages of composite materials and to investigate the behavior of the anisotropic symmetric laminated cylindrical shell structures. To analyze the anisotropic symmetric laminated cylindrical shell structures, the finite difference technique. that consists of forward, central and backward difference, is introduced. In this study, the degree of freedom consists of three displacements and, especially, two moments except twisting moment. It has the advantage of improving the accuracy for calculating the moments. All four edges are assumed to be simply supported. From the numerical results, it is proved that the finite difference technique can be used efficiently to analyze the anisotropic symmetric laminated cylindrical shells and gives a guide in deciding how to make use of the fiber angle the anisotropic symmetric laminated cylindrical shells.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.7 no.6
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• pp.36-41
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• 1998

The objective of this study is to investigate effects of prebuckling on the buckling of laminated composite cylindrical shells. axial compression is considered for laminated composite cylindrical shells with length to radius ratios. The shell walls are made of a laminate with several symmetric ply orientations. This study was made using finite difference energy method, utilizing the nonlinear bifurcation branch with nonlinear prebuckling displacements. The results are compared to the buckling loads determined when membrane prebuckling displacements are considered.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1998.03a
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• pp.112-116
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• 1998

The objective of this study is to investigate effects of prebuckling on the buckling of laminated composite cylindrical shells. Axial compression is considered for laminated composite cylindrical shells with length to radius ratios. The shell walls are made of a laminate with several symmetric ply orientations. This study was made using finite difference energy method, utilizing the nonlinear bifurcation branch with nonlinear prebuckling displacements. The results are compared to the buckling loads determined when membrane prebuckling displacements are considered.