• Title/Summary/Keyword: Laminated Composite Structures

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Analysis of Simple Supported Anisotropic Symmetric Laminated Cylindrical Shells (단순지지된 비등방성 대칭 적층 원통형 쉘의 해석)

  • Chai, Sang Youn;Yhim, Sung Soon;Chang, Suk Yoon
    • 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.

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Vibration Analysis of Laminated Composite Corrugated Plates (적층 복합재료 주름판의 진동해석)

  • Park, Kyung-Jo;Kim, Young-Wann
    • Composites Research
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    • v.29 no.6
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    • pp.347-352
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    • 2016
  • This work presents the free vibration characteristics of laminated composite corrugated rectangular plates using the analytical method. Because it is very difficult to determine its mechanical behavior of 3-dimensional corrugated structures analytically, the equivalent homogenization model is adapted to investigate the overall mechanical behavior of corrugated structures. The corrugated element can be homogenized as an orthotropic material. Both the effective extensional and flexural stiffness of this homogenized equivalent orthotropic material are considered in the analysis. The present analytical results are validated by those obtained from 3D finite element analysis based on shell elements. The natural frequencies and global vibration mode shapes obtained from present analytical and finite element analysis are presented. Some numerical results are presented to check the effect of the geometric properties.

Prediction of the Onset of Failures in Composite Laminated Plates with Uncertain Material Properties (불확실한 물성치를 갖는 복합재료 적층 평판의 파괴 예측)

  • Kim, Tae-Uk;Sin, Hyo-Cheol
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.24 no.1 s.173
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    • pp.259-268
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    • 2000
  • Because of their superior mechanical properties to isotropic materials, composite laminated plates are used for many structural applications that require high stiffness-to-weight and strength-to-weight ratios. Composite materials are always subject to a certain amount of scatter in their elastic moduli, but most analyses and designs with the materials are usually conducted by assuming that the material properties are fixed and have no uncertainties. In this paper, a convex modeling approach is introduced to take account of such uncertainties in elastic moduli. It is used with the finite element method to predict the onset of failures in composite laminated plates subject to in-plane loading. Numerical results show that failures begin at the smaller load when the uncertainties of elastic moduli considered and therefore, such uncertainties should be considered at the design stage for the safety and reliability of the structures.

Optimal Design of Laminated Composite Beams with Open Cross Section (복합 적층 개단면 보의 최적설계)

  • 배하록;홍순호;신영석
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 1999.10a
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    • pp.309-316
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    • 1999
  • Laminated composite plates are very useful in various fields of engineering where high strength-to-weight and stiffness-to-weight ratios are required. Design optimization of composite structures has gained importance in recent years as the engineering applications of fiber reinforced materials have increased and weight savings has become an essential design objective. However, due to the anisotropic material properties of laminated composite structure it is very difficult to analyze and design. In this study, numerical optimization technique together with the finite element method is used to find the optimum design of FRP. Various combination of fiber orientation for the laminate layers are investigated and several local optimum solutions are found.

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Investigation of the effect of shell plan-form dimensions on mode-shapes of the laminated composite cylindrical shallow shells using SDSST and FEM

  • Dogan, Ali;Arslan, H. Murat
    • Steel and Composite Structures
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    • v.12 no.4
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    • pp.303-324
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    • 2012
  • This paper presents the mode-shape analysis of the cross-ply laminated composite cylindrical shallow shells. First, the kinematic relations of strains and deformation are given. Then, using Hamilton's principle, governing differential equations are developed for a general curved shell. Finally, the stress-strain relation for the laminated, cross-ply composite shells are obtained. By using some simplifications and assuming Fourier series as a displacement field, the governed differential equations are solved by the matrix algebra for shallow shells. Employing the computer algebra system called MATHEMATICA; a computer program has been prepared for the solution. The results obtained by this solution are compared with the results obtained by (ANSYS and SAP2000) programs, in order to verify the accuracy and reliability of the solution presented.

Nonlinear vibration of laminated composite plates subjected to subsonic flow and external loads

  • Norouzi, Hamed;Younesian, Davood
    • 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.

Behaviors of Laminated Composite Folded Structures According to Ratio of Folded Length (곡절 길이비에 따른 복합적층 절판 구조물의 거동)

  • Yoo Yong-Min;Yhim Sung-Soon;Chang Suk-Yoon
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.19 no.3 s.73
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    • pp.223-231
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    • 2006
  • This study deals with behavior characteristics of laminated composite folded structures according to ratio of folded length based on a higher-order shear deformation theory. Well-known mixed finite element method using Lagrangian and Hermite shape interpolation functions is a little complex and have some difficulties applying to a triangular element. However, a higher-order shear deformation theory using only Lagrangian shape interpolation functions avoids those problems. In this paper, a drilling degree of freedom is appended for more accurate analysis and computational simplicity of folded plates. There are ten degrees of freedom per node, and four nodes per element. Journal on folded plates for effects of length variations is not expressed. Many results in this study are carried out according to ratio of folded length. The rational design is possible through analyses of complex and unpredictable laminated composite folded structures.

Stability of the porous orthotropic laminated composite plates via the hyperbolic shear deformation theory

  • Ferruh Turan
    • Steel and Composite Structures
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    • v.48 no.2
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    • pp.145-161
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    • 2023
  • This study investigates the influences of porosity on the stability of the orthotropic laminated plates under uniaxial and biaxial loadings based on the hyperbolic shear deformation theory. Three different porosity distribution are considered with three specific functions through the plate thickness. The stability equations of porous orthotropic laminated plates are derived by the virtual work principle. Applying the Galerkin method to partial differential equations, the critical buckling load relation of porous orthotropic laminated plates is obtained. After validating the accuracy of the proposed formulation in accordance with the available literature, a parametric analysis is performed to observe the sensitivity of the critical buckling load to shear deformation, porosity, orthotropy, loading factor, and different geometric properties.

Health Monitoring in Composite Structures using Piezoceramic and fiber Optic Sensors (압전세라믹 센서와 광섬유 센서를 이용한 복합재 구조물의 건전성 모니터링)

  • Kim, C.G.;Sung, D.U.;Kim, D.H.;Bang, H.J.
    • Journal of the Korean Society for Nondestructive Testing
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    • v.23 no.5
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    • pp.445-454
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    • 2003
  • Health monitoring is a major concern not only in the design and manufacturing but also in service stages for composite laminated structures. Excessive loads or low velocity impact can cause matrix cracks and delaminations that may severely degrade the load carrying capability of the composite laminated structures. To develop the health monitoring techniques providing on-line diagnostics of smart composite structures can be helpful in keeping the composite structures sound during their service. In this study, we discuss the signal processing techniques and some applications for health monitoring of composite structures using piezoceramic sensors and fiber optic sensors.

A four-node degenerated shell element with drilling degrees of freedom

  • Kim, Ji-Hun;Lee, Byung-Chai
    • Structural Engineering and Mechanics
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    • v.6 no.8
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    • pp.921-937
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    • 1998
  • A new four-node degenerated shell element with drilling degrees of freedom (DOF) is proposed. Allman-type displacement approximation is incorporated into the formulation of degenerated shell elements. The approximation improves in-plane performance and eliminates singularities of system matrices resulted from DOF deficiency. Transverse shear locking is circumvented by introducing assumed covariant shear strains. Two kinds of penalty energy are considered in the formulation for the purpose of suppressing spurious modes and representing true drilling rotations. The proposed element can be applied to almost all kinds of shell problems including composite laminated shell structures and folded shell structures. Numerical examples show that the element is of good accuracy and of reasonably fast convergence rate.