• Title/Summary/Keyword: Laminated Composite Structures

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Buckling of symmetrically laminated quasi-isotropic thin rectangular plates

  • Altunsaray, Erkin;Bayer, Ismail
    • Steel and Composite Structures
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    • v.17 no.3
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    • pp.305-320
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    • 2014
  • The lowest critical value of the compressive force acting in the plane of symmetrically laminated quasi-isotropic thin rectangular plates is investigated. The critical buckling loads of plates with different types of lamination and aspect ratios are parametrically calculated. Finite Differences Method (FDM) and Galerkin Method are used to solve the governing differential equation for Classical Laminated Plate Theory (CLPT). The results calculated are compared with those obtained by the software ANSYS employing Finite Elements Method (FEM). The results of Galerkin Method (GM) are closer to FEM results than those of FDM. In this study, the primary aim is to conduct a parametrical performance analysis of proper plates that is typically conducted at preliminary structural design stage of composite vessels. Non-dimensional values of critical buckling loads are also provided for practical use for designers.

Thermal buckling analysis of cross-ply laminated plates using a simplified HSDT

  • Chikh, Abdelbaki;Tounsi, Abdelouahed;Hebali, Habib;Mahmoud, S.R.
    • Smart Structures and Systems
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    • v.19 no.3
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    • pp.289-297
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    • 2017
  • This work presents a simplified higher order shear deformation theory (HSDT) for thermal buckling analysis of cross-ply laminated composite plates. Unlike the existing HSDT, the present one has a new displacement field which introduces undetermined integral terms and contains only four unknowns. Governing equations are derived from the principle of the minimum total potential energy. The validity of the proposed theory is evaluated by comparing the obtained results with their counterparts reported in literature. It can be concluded that the proposed HSDT is accurate and simple in solving the thermal buckling behavior of laminated composite plates.

Iron Loss Comparison between Soft Magnetic Composite Core and Laminated Steel Core in Axial Flux Machine (축방향 자속형 전동기에서 연자성복합체 코어와 적층 전기강판 코어의 철손 비교)

  • Lee, Minhyeok;Nam, Kwanghee
    • Proceedings of the KIPE Conference
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    • 2015.11a
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    • pp.217-218
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    • 2015
  • Two axial flux permanent magnet (AFPM) machines using soft magnetic composite (SMC) and lamination steel are studied. Generally stator cores of AFPM machines are manufactured using SMC because AFPM machines need 3 dimensional core structures. However, SMC cores have very disadvantages in magnetic properties. Especially permeability value is much lower than that of lamination steel, so magnetic field density is also lower. In terms of core losses, SMC cores have much larger loss values than lamination steel cores because SMC core can't be laminated. In this study, AFPM machine was designed using laminated steel, and iron losses in two machines using SMC and laminated steel were studied. Simulations were carried out by a commercial 3-D FEM tool.

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Numerical approaches for vibration response of annular and circular composite plates

  • Baltacioglu, Ali Kemal;Civalek, Omer
    • Steel and Composite Structures
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    • v.29 no.6
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    • pp.759-770
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    • 2018
  • In the present investigation, by using the two numerical methods, free vibration analysis of laminated annular and annular sector plates have been studied. In order to obtain the main equations two different shell theories such as Love's shell theory and first-order shear deformation theory (FSDT) have been used for modeling. After obtaining the fundamental equations in briefly, the methods of harmonic differential quadrature (HDQ) and discrete singular convolution (DSC) are used to solve the equation of motion. Accuracy, convergence and reliability of the present HDQ and DSC methods were tested by comparing the existing results obtained by different methods in the literature. The effects of some geometric and material properties of the plates are investigated via these two methods. The advantages and accuracy of the HDQ and DSC methods have also been examined with different grid numbers and shell theory. Some results for laminated annular plates and laminated circular plates were also been supplied.

Size dependent vibration of laminated micro beams under moving load

  • S.D. Akbas
    • Steel and Composite Structures
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    • v.46 no.2
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    • pp.253-261
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    • 2023
  • The goal of this paper is to investigate dynamic responses of simply-supported laminated micro beams under moving load. In the considered micro-scale problem, the modified coupled stress theory which includes the length scale parameter is used. The governing equations of problem are derived by using the Lagrange procedure. In the solution of the problem the Ritz method is used and algebraic polynomials are used with the trivial functions for the Ritz method. In the solution of the moving load problem, the Newmark average acceleration method is used in the time history. In the numerical examples, the effects of stacking sequence of laminas, fibre orientation angles and the length scale parameter on the dynamic responses of laminated micro beams are examined and discussed.

Static analysis of multilayer nonlocal strain gradient nanobeam reinforced by carbon nanotubes

  • Daikh, Ahmed Amine;Drai, Ahmed;Houari, Mohamed Sid Ahmed;Eltaher, Mohamed A.
    • Steel and Composite Structures
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    • v.36 no.6
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    • pp.643-656
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    • 2020
  • This article presents a comprehensive static analysis of simply supported cross-ply carbon nanotubes reinforced composite (CNTRC) laminated nanobeams under various loading profiles. The nonlocal strain gradient constitutive relation is exploited to present the size-dependence of nano-scale. New higher shear deformation beam theory with hyperbolic function is proposed to satisfy the zero-shear effect at boundaries and parabolic variation through the thickness. Carbon nanotubes (CNTs), as the reinforced elements, are distributed through the beam thickness with different distribution functions, which are, uniform distribution (UD-CNTRC), V- distribution (FG-V CNTRC), O- distribution (FG-O CNTRC) and X- distribution (FG-X CNTRC). The equilibrium equations are derived, and Fourier series function are used to solve the obtained differential equation and get the response of nanobeam under uniform, linear or sinusoidal mechanical loadings. Numerical results are obtained to present influences of CNTs reinforcement patterns, composite laminate structure, nonlocal parameter, length scale parameter, geometric parameters on center deflection ad stresses of CNTRC laminated nanobeams. The proposed model is effective in analysis and design of composite structure ranging from macro-scale to nano-scale.

Stability of Cantilevered Laminated Composite Structures with Open Channel Section by Geometrical Shape Variations (채널단면의 기하학적 형상변화에 따른 캔틸레버 적층구조물의 안정성 연구)

  • Park, Won-Tae;Chun, Kyoung-Sik;Son, Byung-Jik
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.8 no.2
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    • pp.169-175
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    • 2004
  • In this paper, the stability of cantilever composite laminated structures with open channel section is studied. This paper deals with the buckling behavior under the variation of the geometrical shape (length ratio, crank angle in the open channel section), the fiber reinforced angle, and so on in order to offer a effective and reliable design data. Also, sensitive analyses are carried out on the stability by the interaction of design factors. Based on this fact, the proper channel section and lamination scheme of composite material cantilever structures are considered in the engineering aspect.

Buckling Analysis of Laminated Composite Plates Longitudinally Stiffened with U-Shaped Ribs (축방향 압축을 받는 폐단면리브로 보강된 복합적층판의 좌굴 해석연구)

  • Choi, Byung-Ho;Choi, Su-Young;Park, Sang-Kyun
    • Journal of the Korean Society for Advanced Composite Structures
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    • v.3 no.1
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    • pp.29-34
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    • 2012
  • Even though the longitudinally stiffened laminated composite plates with closed section ribs should be an effective system for axially compressed members, the existing researches on the applications of closed-section ribs, especially for the laminated composite plates, are not sufficient. This study is aimed to examine the influence of the sectional stiffness of U-shaped ribs on the buckling modes and strengths of laminated composite plates. Applying the orthotropic plates with eight layers of the layup $[(0^{\circ})_4]_s$ and $[(0^{\circ}/90^{\circ})_2]_s$, 3-dimensional finite element models for the U-rib stiffened plates were setup by using ABAQUS and then a series of eigenvalue analyses were conducted. From the parametric studies, the minimum required ply thicknesses as well as the buckling strengths were presented for the analysis models. The buckling strengths were compared with the theoretical critical stress equation for simply supported plates based on the Classical laminated plate theory. This study will contribute to the future study for evaluating the minimum required stiffness and optimum design of U-rib stiffened plates.

Evaluation of Bending Creep Performance of Laminated Veneer Lumber (LVL) Formwork for the Design of Timber Concrete Composite (TCC) Structures

  • Hyun Bae KIM;Takuyuki YOSHIOKA;Kazuhiko FUJITA;Jun ITO;Haruka NOHARA;Keiji NOHARA;Toshiki NARITA;Wonwoo LEE;Arata HOSOKAWA;Tetsuiji TANAKA
    • Journal of the Korean Wood Science and Technology
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    • v.52 no.4
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    • pp.375-382
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    • 2024
  • The study focuses on evaluating the bending creep performance of laminated veneer lumber (LVL) formwork in timber concrete composite (TCC) structures. Timber-framed construction is highlighted for its environmental benefits and seismic resistance, but limitations such as poor tensile strength and brittle failure in bending hinder its use in high-rise buildings. Wood-concrete hybrid structures, particularly those using reinforced concrete slabs with TCC floors, emerge as a potential solution. The research aims to understand the time-dependent behavior of TCC components, considering factors like wood and concrete shrinkage and connection creep. The experiment was conducted in western Japan on the TCC floor designed for use in the Kama-city Inatsuki-higashi compulsory education school. The LVL formwork, measuring 9,000 mm by 900 mm, and concrete is loaded onto it for testing. The creep test periods are examined using concrete loading. It employs a comprehensive creep analysis, adhering to Japanese standards, involving deflection measurements and regression analysis to estimate the creep coefficient. Results indicate substantial deformation after shoring removal, suggesting potential reinforcement needs. The study recommends extending test periods for improved accuracy and recognizing regional climate impacts. Overall, the research provides valuable insights into the potential of LVL formwork in TCC structures, emphasizing safety considerations and paving the way for further experimentation under varied conditions to validate structural integrity.

Layup Optimization of Composite Laminates with Free Edge Considering Bounded Uncertainty (물성치의 불확실성을 고려한 자유단이 있는 복합재료 적층평판의 최적화)

  • 조맹효;이승윤
    • Proceedings of the Korean Society For Composite Materials Conference
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    • 2001.05a
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    • pp.155-158
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    • 2001
  • The layup optimization by genetic algorithm (GA) for the strength of laminated composites with free-edge is presented. For the calculation of interlaminar stresses of composite laminates with free edges, extended Kantorovich method is applied. In the formulation of GA, repair strategy is adopted for the satisfaction of given constraints. In order to consider the bounded uncertainty of material properties, convex modeling is used. Results of GA optimization with scattered properties are compared with those of optimization with nominal properties. The GA combined with convex modeling can work as a practical tool for light weight design of laminated composite structures since uncertainties are always encountered in composite materials.

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