• Title, Summary, Keyword: Thick Composite Laminates

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Cure simulation for a thick glass/epoxy laminate (유리섬유 강화 후판 복합재료의 경화공정 해석)

  • 오제훈;이대길
    • Proceedings of the Korean Society For Composite Materials Conference
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    • pp.53-58
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    • 2000
  • During the curing process of thick glass/epoxy laminates, a substantial amount of temperature lag and overshoot at the center of the laminates is usually experienced due to the large thickness and low thermal conductivity of the glass/epoxy composites. Also, it requires a longer time for full and uniform consolidation. In this work, temperature, degree of cure and consolidation of a 20mm thick unidirectional glass/epoxy laminate were investigated using an experiment and a 3-dimentional numerical analysis considering the exothermic reaction. From the experimental and numerical results, it was found that the experimentally obtained temperature profile agreed well with the numerical one and the cure cycle recommended by the prepreg manufacturer should be modified to prevent a temperature overshoot and to obtain full consolidation.

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Dynamics of thick hygrothermal viscoelastic composite laminates through finite element method

  • Assie, Amr E.;Mahmoud, Fatin F.
    • Structural Engineering and Mechanics
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    • v.17 no.5
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    • pp.727-734
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    • 2004
  • An uncoupled computational model for analyzing the hygrothermal dynamic response of composite laminates has been developed. The constitutive equations, expressed in an integral form, and involving relaxation moduli are adopted, to describe the non-aging hygrothermorheologically simple materials. A Prony series represents the relaxation moduli is exploited in order to derive a recursive relationship, and thereby eliminate the storage problem that arises when dealing with material possessing memory. The problem is formulated in a descritized variational form. Mindlin and higher order finite elements are employed for spatial descretization, while the Newmark average acceleration scheme is exploited for temporal descritization. The adopted recursive formula uses only the details of the previous event to compute the details of the current one. Numerical results of the displacement fields of both thin and thick viscoelastic laminates problems are discussed to show up the effectiveness of Mindlin and higher-order shear theories.

Thermal Buckling of Thick Laminated Composite Plates under Uniform Temperature Distribution (균일분포 온도하의 두꺼운 복합 재료 적층판의 열적 좌굴 해석)

  • Lee, Young-Shin;Lee, Yeol-Wha;Yang, Myung-Seog;Park, Bock-Sun;Lee, Jong-Soo
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.17 no.7
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    • pp.1686-1699
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    • 1993
  • In this paper, the thermal buckling of thick composite angle-ply laminates subject to uniform temperature distribution is studied. For the plates of 4-edges simply supported condition and those of 4-edges clamped condition, the critical buckling temperatue is derived, using tile finite element method based on the shear deformation theory. The effects of lamination angle, layer number, laminate thickness, plate aspect ratio and boundary constraints upon the critical buckling temperature are presented.

Dynamic analysis for anti-symmetric cross-ply and angle-ply laminates for simply supported thick hybrid rectangular plates

  • Benhenni, Mohamed Amine;Daouadji, Tahar Hassaine;Abbes, Boussad;Adim, Belkacem;Li, Yuming;Abbes, Fazilay
    • Advances in materials Research
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    • v.7 no.2
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    • pp.119-136
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    • 2018
  • In this paper, static and vibration analysis for anti-symmetric cross-ply and angle- ply carbon/glass hybrid laminates rectangular composite plate are presented. In this analysis, the equations of motion for simply supported thick laminated hybrid rectangular plates are derived and obtained through the use of Hamilton's principle. The closed-form solutions of anti-symmetric cross-ply and angle- ply laminates are obtained using Navier solution. The effects of side-to-thickness ratio, aspect ratio, and lamination schemes on the fundamental frequencies loads are investigated. The study concludes that shear deformation laminate theories accurately predict the behavior of composite laminates, whereas the classical laminate theory over predicts natural frequencies. The excellent accuracy of the present analytical solution is confirmed by making some comparisons of the present results with those available in the literature. It can be concluded that the proposed theory is accurate and simple in solving the free vibration behaviors of anti-symmetric cross-ply and angle- ply hybrid laminated composite plates.

Stacking method of thick composite laminates considering interlaminar normal stresses (층간수직응력을 고려한 두꺼운 복합적층판의 적층방법)

  • 김동민;홍창선
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.12 no.5
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    • pp.944-951
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    • 1988
  • Global-Local Laminate Variational Model is utilized to investigate the characteristics of interlaminar stresses in thick composite laminates under uniform axial extension. Various laminates with different fiber orientation and stacking sequences are analyzed to observe the behavior of interlaminar normal stresses. From this result, the interlaminar normal stress distribution along the laminate interfaces is examined and discussed with an existing approximation model. The repeated stacking of Poisson's ratio symmetric sublaminates is found to be the best stacking method of thick composite laminates to reduce the interlaminar normal stresses for the prevention of the free-edge delamination.

Strength of composite notches under shear load (전단하중을 받는 복합재료 다중 노치의 파괴강도)

  • 이재광;황병선;박승범;박인서;윤한기
    • Proceedings of the Korean Society For Composite Materials Conference
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    • pp.50-53
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    • 2001
  • An experimental research work for the fracture and notch strength of thick laminates has been performed to develop high quality composite notches for structural use. Thus, the multi-directional laminates are designed and compared to the baseline aluminum. The difference of notch strength caused by manufacturing techniques is also discussed. The notches of selected materials are evaluated by the static test and low-velocity impact test. Failure modes are also observed and assessed. Material design is evaluated by the FEA(finite element analysis) and confirmed by experiments. The successful results are obtained for thick composite notches, which shows higher strength than aluminum notches.

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Design of Thick Laminated Composite Plates for Maximum Thermal Buckling Load (최대 열적 좌굴하중을 갖는 두꺼운 복합재료 적층판의 설계)

  • Lee, Young-Shin;Lee, Yeol-Wha;Yang, Myung-Seog;Park, Bock-Sun
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.17 no.7
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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.

Matrix Cracking and Delmaination in Laminated Composite Plates Due to Impact (적층복합판의 충격에 의한 모재균열 및 층간분리에 관한 연구)

  • Kim, Moon-Saeng;Park, Seung-Bum
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.21 no.2
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    • pp.317-326
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    • 1997
  • An investigation was performed to study the matrix cracking and delamination in laminated composite plates due to transverse impact. A model was developed for predicting the initiation of the matrix cracking and the shape and size of impact-induced delamination in laminated composite plates resulting from the ballistic impact. The model consists of a stress analysis and a failure analysis. A transient finite element analysis which was based on the higher-order shear deformation theory was adopted for calculating the stresses inside the laminated composite plates during impact. A failure analysis was used to predict the initial intraply matrix cracking and the shape and size of the interface delamination in the laminates. As a results, a shear matrix cracking which was governed by the transverse interlaminar shear stress occured at the middle layer near the midplane of laminates and a bending matrix cracking which was governed by the transverse inplane stress occured at the bottom layer near the surface of laminates. In a thick laminates, a shear matrix cracking generated first at the middle layer of laminates, but in a thin laminates, a bending matrix cracking generated first at the bottom layer of laminates.

Cure simulation and Consolidation for a Thick Glass/Epoxy Laminate (유리섬유/에폭시 후판 복합재료의 경화공정 및 압밀해석)

  • O, Je-Hun;Lee, Dae-Gil
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.24 no.11
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    • pp.2853-2865
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    • 2000
  • During the curing process of thick glass/epoxy laminates, a substantial amount of temperature lag and overshoot at the center of the laminates is usually experienced due to the large thickness and low thermal conductivity of the glass/epoxy composites. Also, it takes a longer time for full and uniform consolidation. In this work, temperature, degree of cure and consolidation of a 20 mm thick unidirectional glass/epoxy laminate were investigated using an experiment and a 3-dimentional numerical analysis. From the experimental and numerical results, it was found that the experimentally obtained temperature profile agreed well with the numerical one, and the cure cycle recommended by the prepreg manufacturer should be modified to prevent a temperature overshoot and to obtain full consolidation.

Cure Monitoring of Thick HSPE/Vinylester Composites with Dielectrometry (유전율 분석법에 의한 두꺼운 HSPE/Vinylester 복합재료의 경화 거동 관찰)

  • 이승구;김동철;주창환
    • Textile Science and Engineering
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    • v.38 no.5
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    • pp.214-221
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    • 2001
  • HSPE/vinylester 50-ply laminates, thicker than 1 inch, were fabricated by compression molding. To investigate the consolidation procedure of thick HSPE/vinylester composites, a dielectrometric(DEM) cure monitoring with dielectric sensors the thermocouples was utilized. Behaviors of the ion viscosity(a reciprocal of ion conductivity) as a dielectric parameter was monitored and evaluated with the resin viscosity. minimum viscosity temperature and cure temperature were analyzed from the dynamic cure experiments. To obtain the proper compaction of composites, step cure process including an intermediate dwell step at 8$0^{\circ}C$ was set-up to coincide the viscosity window between inner and outer layers of the composite. From the result of DEM analysis, the optimum cure cycle for a thick HSPE/vinylester composite in compression molding was established. In addition, the effects of molding pressure on the properties of composites were evaluated.

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