• Steel and Composite Structures
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• v.13 no.3
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• pp.207-223
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• 2012

This paper deals with critical thermal buckling load optimization of symmetrically laminated four layered angle-ply plates with one or two different intermediate line supports. The design objective is the maximization of the critical thermal buckling load and a design variable is the fibre orientation in the layers. The first order shear deformation theory and nine-node isoparametric finite element model are used for the finite element solution of the laminates. The modified feasible direction (MFD) method is used for the optimization routine. For this purpose, a program based on FORTRAN is used. Finally, the numerical analysis is carried out to investigate the effects of location of the internal line supports, plate aspect ratios and boundary conditions on the optimal designs and the results are compared.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2002.04a
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• pp.489-496
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• 2002

The lateral buckling of a laminated composite beam is studied. A general analytical model applicable to the lateral buckling of a composite beam subjected to various types of loadings is derived. This model is based on the classical lamination theory, and accounts for the material coupling for arbitrary laminate stacking sequence configuration and various boundary conditions. The effects of the location of applied loading on the buckling capacity are also included in the analysis. A displace-based one-dimensional finite element model is developed to predict critical loads and corresponding buckling modes for a thin-walled composite beam with arbitrary boundary conditions. Numerical results are obtained for thin-walled composites under central point load, uniformly distributed load, and pure bending with angle-ply and laminates. The effects of fiber orientation location of applied load, and types of loads on the critical buckling loads are parametrically studied.

• Steel and Composite Structures
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• v.22 no.6
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• pp.1261-1280
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• 2016

We study chaotic motion in a nonlinear laminated composite plate under subsonic fluid flow and a simultaneous external load in this paper. We derive equations of motion of the plate using the von-$K{\acute{a}}rm{\acute{a}}n^{\prime}s$ hypothesis and the Hamilton's principle. Galerkin's approach is adopted as the solution method. We then conduct a divergence analysis to obtain critical velocities of the transient flow. Melnikov's integral approach is used to find the critical parameters in which chaos takes place. Effects of different parameters including the aspect ratio, plate material and the ply angle in laminates on the critical flow speed are investigated. In a parametric study, we show that how the linear and nonlinear stiffness of the plate and the load frequency and amplitude would influence the chaotic behavior of the plate.

• Composites Research
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• v.22 no.3
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• pp.60-65
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• 2009

The mechanical behavior of carbon fiber reinforced polymeric (CFRP) composites was investigated. Both strength and modulus were measured at room temperature dry, cold temperature dry, $-55^{\circ}C$, and elevated temperature wet, $82.2^{\circ}C$ on seven different laminate configurations consisting of $[0_6]_T$, $[90_{12}]_T$, $[0_{16}]_T$ and $[90_{16}]_T$ unidirectional laminates, $[{\pm}45]_{5S}$ angle-ply laminate, $[0/90_{12}/0]_T$ cross-ply laminate, a 36-ply laminate $[0/45/-45/45/-45/0]_{3S}$. Based on the experimental data presented, it is shown that the strength at cold temperature dry, $-55^{\circ}C$ is increased with the brittleness of fiber or matrix. Moreover, it is shown that both shear strength and modulus at elevated temperature wet, $82.2^{\circ}C$ are decreased by the cause of interfacial deterioration between fiber and matrix with moisture absorption.

• Journal of the korean Society of Automotive Engineers
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• v.8 no.2
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• pp.51-64
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• 1986

There has been considerable interest over the last twenty years in the subject of the elastic properties of the cord-rubber laminate. This has been due to the rather intensive study of the composites materials characteristics brought about by the increased use of rigid composites materials characteristics brought about by the increased use of rigid composites in many structural applications. The object of this study is to obtain the natural frequencies and modes of the simply supported cord-rubber laminate plates prior to the study on the analysis of the dynamic properties of the pneumatic tire. To obtain these natural frequencies and modes, the 12 degrees of freedom orthotropic rectangular plate finite elements are developed. By using classical lamination theory, the stress-strain relations are represented. The governing equation for the finite element is derived by energy method. To find the natural frequencies and modes, he eigenvalues and corresponding eigenvectors are computed by the well known Jacobi power method. In order to verify the capability of this present finite element, the results of the specially orthotropic plate and the angle-ply laminate plate are compared with the analytical solution. The analytical and numberical results are in good agreement. The following problems of the simply supported plate are analyzed by the present finite element. a) the natural frequencies and mode shapes of the cord-rubber laminate plate for various aspect ratio. b) The natural frequencies and mode shapes of the orthotropic plate with the rectangular hole in its center.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.9
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• pp.3176-3183
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• 2010

A multi-scale fatigue life prediction methodology of composite pressure vessels subjected to multi-axial loading has been proposed in this paper. The multi-scale approach starts from the constituents, fiber, matrix and interface, leading to predict behavior of ply, laminates and eventually the composite structures. The multi-scale fatigue life prediction methodology is composed of two steps: macro stress analysis and micro mechanics of failure based on fatigue analysis. In the macro stress analysis, multi-axial fatigue loading acting at laminate is determined from finite element analysis of composite pressure vessel, and ply stresses are computed using a classical laminate theory. The micro stresses are calculated in each constituent from ply stresses using a micromechanical model. Three methods are employed in predicting fatigue life of each constituent, i.e. a maximum stress method for fiber, an equivalent stress method for multi-axially loaded matrix, and a critical plane method for the interface. A modified Goodman diagram is used to take into account the generic mean stresses. Damages from each loading cycle are accumulated using Miner's rule. Monte Carlo simulation has been performed to predict the overall fatigue life of a composite pressure vessel considering statistical distribution of material properties of each constituent, fiber volume fraction and manufacturing winding angle.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.10
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• pp.907-911
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• 2016

This paper provides the compressive failure strength value of composite laminate developed by using regression analysis method. Composite material in this document is a Carbon/Epoxy unidirection(UD) tape prepreg(Cycom G40-800/5276-1) cured at $350^{\circ}F(177^{\circ}C$). The operating temperature is -$-60^{\circ}F{\sim}+200^{\circ}F$($-55^{\circ}C{\sim}+95^{\circ}C$). A total of 56 compression tests were conducted on specimens from eight (8) distinct laminates that were laid up by standard angle layers ($0^{\circ}$, $+45^{\circ}$, $-45^{\circ}$ and $90^{\circ}$). The ASTM-D-6484 standard was used for test method. The regression analysis was performed with the response variable being the laminate ultimate fracture strength and the regressor variables being two ply orientations ($0^{\circ}$ and ${\pm}45^{\circ}$).

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.10
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• pp.959-965
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• 2017

In recent years, major airplane manufacturers have been using the laminate failure theory to estimate the strain of composite structures for airplanes. The laminate failure theory uses the failure strain of the laminate to analyze composite structures. This paper describes a procedure for the experimental assessment of laminate tensile failure characteristics. Regression analysis was used as the experimental assessment method. The regression analysis was performed with the response variable being the laminate failure strain and with the regressor variables being two-ply orientation ($0^{\circ}$ and ${\pm}45^{\circ}$) variables. The composite material in this study is a carbon/epoxy unidirectional (UD) tape that was cured as a pre-preg at $177^{\circ}C(350^{\circ}F)$. A total of 149 tension tests were conducted on specimens from 14 distinct laminates that were laid up at standard angle layers ($0^{\circ}$, $45^{\circ}$, $-45^{\circ}$, and $90^{\circ}$). The ASTM-D-3039 standard was used as the test method.