• Title/Summary/Keyword: Stacking Sequences

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A Study on the Vibration Characteristics of Laminated Composite Rectangular Plate using ANSYS (ANSYS를 이용한 복합 적층 사각판의 진동특성에 관한 연구)

  • 이기형
    • Journal of the Korean Society of Safety
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    • v.12 no.2
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    • pp.37-44
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    • 1997
  • Composite materials have various complicated characteristics depending on the ply materials, ply orientations, ply stacking sequences and boundary conditions. Therefore, it is difficult to analyze composite materials. For efficient use of composite materials in engineering applications, the dynamic behavior such as natural frequencies and nodal patterns should be identified. This study presents FEM results for the free vibration of symmetrically and antisymmetrically laminated composite and hybrid composite rectangular plates. The natural frequencies of laminated composite rectangular plates having the various boundary conditions (completely clamped, 2-edge clamped, cantilevered) are experimentally obtained. In order to demonstrate the validity of the experiment, FEM analysis using ANSYS was performed and natural frequencies experimentally obtained is compared with that calculated by FEM analysis. The results obtained from both experiment and FEM analysis show a good agreement.

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Analysis of the residual strengths and failure mechanisms in laminated composites under impact loading

  • Park, K.C.;Kim, M.S.
    • Journal of the Korean Society for Precision Engineering
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    • v.11 no.3
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    • pp.105-121
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    • 1994
  • In this paper, we proposed the two-parameter model for predicting the residual strength in CFRP laminated composites subjected to high velocity impact and developed and formulated it based upon Cparino's by using the ratio of impact and the normalized residual strength. Critical indentation was obtained by the statical indentation tests. Impact tests were carried out through air-gun type impact equipment with the velocities varied 30-100m/sec. Projectiles were steel balls with 5 and 7mm in diameter. Test material was carbon/epoxy. The specimens were composed of [ .+-. 45 .deg. /0 .deg. /90 .deg. ]$\_$2/ and [ .+-. 45 .deg. ]$\_$4/stacking sequences and had 0.75$\^$T/*0.26$\^$W/*100$\^$L/(mm) dimension. Results from the proposed model were in good agreement with the test data. And failure mechanism due to high velocity impact is given here to examine the initation and deveolpment of damage by fractography and ultrasonic image system. The effects of the 0 .deg. -direction ply position and the amount to damage area on the residual strength are considered here.

Optimal Lamination Design of Composite Cylinders using an Empirical Ultimate Pressure Load Formula (최종강도 경험식을 이용한 복합재 원통구조의 최적적층 설계)

  • Cho, Yoon Sik;Paik, Jeom Kee
    • Journal of the Society of Naval Architects of Korea
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    • v.56 no.4
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    • pp.316-326
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    • 2019
  • In this paper, a methodology is presented for determining the optimal lamination of composite cylindrical structures subject to hydrostatic pressure. The strength criterion in association with the process of optimal design is the buckling collapse of composite cylinders under hydrostatic pressure loads. An empirical formula expressed in the form of the Merchant-Rankine equation is used to calculate the ultimate strength of filament-wound composite cylinders where genetic algorithm is applied for determining the optimized stacking sequences. It is shown that the optimized lamination provides improved collapse pressure loads. It is concluded that the developed method would be useful for the optimal lamination design of composite cylindrical structures.

Illite Polytypes: The Characteristics and the Application to the Fault Age Determination (일라이트 폴리타입: 그 특성과 단층 활동연대 결정에의 활용)

  • Song, Yun-Goo
    • Economic and Environmental Geology
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    • v.45 no.2
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    • pp.181-188
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    • 2012
  • The 1M and $2M_1$ stacking sequences are the most frequently encountered in the illite species among the possible 6 polytypes. The $1M_d$, derived from the 1M polytype which exhibits a variable degree of disorder in the stacking sequence, is also observed in illite samples. In this paper, the author introduces and reviews the theoretical background of the quantitative analysis method of illite polytypes, and considers the possibility to determine the fault age and its reactivation age using K/Ar age-dating based on the quantification of illite polytypes in the fault system. For the increase of the accuracy and precision of the illite age analysis method, the occurrence, identification, and mineralogical characterization of illite polytypes should be defined in detail. The broadening effect of (hkl) reflections, due to disordering of 1M polytype and the presence of I/S minerals with expandability, are also considered as the main parameters controlling the quantification of illite polytypes using the WILDFIRE(C)simulation.

A Study on Characterization for Stacking Fault Evaluation of CFRP Composite Laminates Using an EMAT Ultrasonics (전자기 초음파를 이용한 CFRP 복합적층판의 적층배향 특성평가에 관한 연구)

  • Im, Kwang-Hee;Na, Seung-Woo;Kim, Ji-Hoon;Lee, Chang-Ro;Hsu, David K.;Yang, In-Young
    • Transactions of the Korean Society of Automotive Engineers
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    • v.13 no.2
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    • pp.83-92
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    • 2005
  • An electromagnetic acoustic transducer (EMAT) is a unique probe that does not require a couplant or gel and also can usually generate or detect an ultrasonic wave into specimens across a small gap. It, therefore can be applied in a noncontact mode with a high degree of reproducibility. Especially stiffness of composites depends on layup sequence of CFRP(carbon fiber reinforced plastics) laminates. It is very important to evaluate the layup errors in prepreg laminates. A nondestructive technique can therefore serve as a useful measurement for detecting layup errors. This shear wave for detecting the presence of the errors is very sensitive. A decomposition model has been used in the interpretation and prediction of test results. Test results have been com pared with model data. It is found that the high probability shows between tests and the model utilized in characterizing cured layups of the laminates. Also a C-scan method was used for detecting layup of the laminates because of extracting fiber orientation information from the ultrasonic reflection caused by structural imperfections in the laminates. Therefore, it was found that interface C-scan images show the fiber orientation information by using two-dimensional fast Fourier transform (2-D FFT).

Utilization of Finite Element Analysis in Design and Performance Evaluation of CFRP Bicycle Frames (유한요소해석을 이용한 CFRP 자전거 프레임의 설계 및 성능 평가)

  • Lee, Yong-Sung;Shin, Ki-Hoon;Cheong, Seong-Kyun;Choi, Ung-Jae;Kim, Young-Keun;Park, Kyung-Rea;Kim, Hong Seok
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.37 no.1
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    • pp.121-127
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    • 2013
  • With the continuing demand for lightweight bicycles, carbon fiber composite materials have been widely used in manufacturing bicycle frames and components. Unlike general isotropic materials, the structural characteristics of composite materials are strongly influenced by the staking directions and sequences of composite laminates. Thus, to verify the design process of bicycles manufactured using composites, structural analysis is considered essential. In this study, a carbon-fiber-reinforced plastic (CFRP) bicycle frame was designed and its structural behavior was investigated using finite element analysis (FEA). By measuring the failure indices of the fiber and matrix under various stacking sequences and loading conditions, the effect of the stacking condition of composite laminates on the strength of the bicycle structure was examined. In addition, the structural safety of the bicycle frame can be enhanced by reinforcing weak regions prone to failure using additional composite laminates.

Progressive Damage and Failure Analysis of Open-Hole Composite Specimens Under Compressive Loading Using Finite Element Analysis (유한요소해석을 이용한 압축 하중을 받는 오픈 홀 복합재 시편의 점진적 손상 및 파손 분석)

  • Young Cheol Kim;Geunsu Joo;Hong-Kyu Jang;Jinbong Kim;Min-Gyu Kang;Woo-Kyoung Lee;Ji Hoon Kim
    • Composites Research
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    • v.36 no.5
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    • pp.303-309
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    • 2023
  • In this paper, a Progressive Damage and Failure Analysis (PDFA) modeling method was developed using ABAQUS/EXPLICIT to predict in-plane damage and delamination for Open-Hole Compression (OHC) testing. The proposed PDFA model was constructed based on Hashin criteria and cohesive behavior. The strength and stiffness of OHC specimens with three types of stacking sequences [(45/-45/02)3]s , [(45/0/-45/90)3]s and [45/-45/0/45/-45/90/(45/-45)2]s were compared to comprehensively evaluate the validity of the Finite Element(FE) model of PDFA. The strength and stiffness of the OHC specimens were predicted relatively well, with less than a percentage error 10.0 %. For the numerical simulation case for each layup, the damage initiation/evolution of OHC specimens were evaluated for delamination and tension/compression matrix damage before and after failure.

Thickness Effect on the Compressive Strength of T800/924C Carbon Fibre-Epoxy Laminates (T800/924C 탄소-에폭시 복합재판의 압축강도에 대한 두께 효과)

  • Lee, J.;C. Kong;C. Soutis
    • Composites Research
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    • v.17 no.4
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    • pp.7-17
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    • 2004
  • In this study, the effect of laminate thickness on the compressive behaviour of composite materials is investigated through systematic experimental work using the stacking sequences, $[O_4]_{ns},{\;}[45/0/-45/90]_{ns}$ and $[45_n/0_n/-45_n/90_n]_s$ (n=2 to 8). Parameters such as fibre volume fraction, void content, fibre waviness and interlaminar stresses, influencing compressive strength with increasing laminate thickness are also studied experimentally and theoretically. Furthermore the stacking sequence effects on failure strength of multidirectional laminates are examined. For this purpose, two different scaling techniques are used; (1) ply-level technique $[45_n/0_n/-45_n/90_n]s$ and (2) sublaminate level technique $[45/0/-45/90]_{ns}$. An apparent thickness effect existes in the lay-up with blocked plies, i.e. unidirectional specimens ($[O_4]_{ns}) and ply-level scaled multidirectional specimens ($[45_n/0_n/-45_n/90_n]_s$). Fibre waviness and void content are found to be main parameters contributing to the thickness effect on the compressive failure strength. However, the compressive strength of the sublaminate level scaled specimens ($[45/0/-45/90]_{ns}$) is almost unaffected regardless of the specimen thickness (since ply thickness remains constant). From the investigation of the stacking sequence effect, the strength values obtained from the sublaminate level scaled specimens are slightly higher than those obtained from the ply level scaled specimens. The reason for this effect is explained by the fibre waviness, void content, free edge effect and stress redistribution in blocked $0^{\circ}$ plies and unblocked $0^{\circ}$ plies. The measured failure strengths are compared with the predicted values.

Facies and sequence analysis on the Lower Ordovician Mungok Formation (전기 오오도비스기 문곡층의 시퀀스 및 상 분석)

  • Choi Yong Seok;Lee Yong Il
    • The Korean Journal of Petroleum Geology
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    • v.9 no.1_2 s.10
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    • pp.1-15
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    • 2001
  • Hierarchically controlled sequence stratigraphic analysis shows that the Lower Ordovician mixed carbonatesiliciclastic Mungok Formation, Korea consists of three depositional sequences: T1, T2, and T3 in ascending order. Sequence boundaries are generally marked by abrupt transition from coarse-grained shallow-water carbonates to finegrained deeper-water carbonates mixed with fine-grained siliciclastics, and show indication of subaerial exposure such as karstification. Within this sequence stratigraphic framework, facies characteristics indicate that the Mungok sequences were mostly deposited on a subtidal ramp without slope break. The Mungok ramp had been under the influence of frequent tropical storm activity during deposition. The difference in lithology of tempestites seems to have been controlled by the nature of substrates and by proximality. High-frequency cycles consist of upward-shallowing facies successions. Cycles of shallow-water and basinal deposits are not well represented, probably due to cycle amalgamation. Cycle stacking patterns do not show a consistent thickness change that is usually associated with a large-scale sea-level change probably because of unfilled accommodation space.

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Thermal response analysis of multi-layered magneto-electro-thermo-elastic plates using higher order shear deformation theory

  • Vinyas, M.;Harursampath, D.;Kattimani, S.C.
    • Structural Engineering and Mechanics
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    • v.73 no.6
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    • pp.667-684
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    • 2020
  • In this article, the static responses of layered magneto-electro-thermo-elastic (METE) plates in thermal environment have been investigated through FE methods. By using Reddy's third order shear deformation theory (TSDT) in association with the Hamilton's principle, the direct and derived quantities of the coupled system have been obtained. The coupled governing equations of METE plates have been derived through condensation technique. Three layered METE plates composed of piezoelectric and piezomagnetic phases are considered for evaluation. For investigating the correctness and accuracy, the results in this article are validated with previous researches. In addition, a special attention has been paid to evaluate the influence of different electro-magnetic boundary conditions and pyrocoupling on the coupled response of METE plates. Finally, the influence of stacking sequences, magnitude of temperature load and aspect ratio on the coupled static response of METE plates are investigated in detail.