• Title, Summary, Keyword: 적층배열

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Development of 3D Woven Preform π-beam based on T-beam Made of Laminated Composites (적층복합재료 T-빔 기반의 3차원 직조 프리폼 π-빔 개발)

  • Park, Geon-Tae;Lee, Dong-Woo;Byun, Joon-hyung;Song, Jung-il
    • Composites Research
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    • v.33 no.3
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    • pp.115-124
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    • 2020
  • Laminate composites, especially Carbon fiber-reinforced composites are wide used in various industry such as aerospace and automotive industry due to their high specific strength and specific stiffness. However, the laminate composites has a big disadvantage that delamination occurs because the arrangement of the fibers is all arranged in the in-plane direction, which limits the field of application of the laminate composites. In this study, we first developed a laminate composites T-beam in which π-beam and flat plate were combined and optimized the design parameters through structural analysis and mechanical tests. Afterwards, 3D weave preform T-beam was developed by applying the same design parameters of laminate composites T-beams, and improved mechanical strength was achieved compared to laminated structures. These findings are expected to be applicable to existing laminated composite structures that require increased strength.

A Study on the Shaped-Beam Antenna with High Gain Characteristic (고이득 특성을 갖는 성형 빔 안테나에 대한 연구)

  • Eom, Soon-Young;Yun, Je-Hoon;Jeon, Soon-Ick;Kim, Chang-Joo
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.18 no.1
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    • pp.62-75
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    • 2007
  • This paper describes a shaped-beam antenna for increasing the antenna gain of a radiating element. The proposed antenna structure is composed of an exciting element and a multi-layered disk array structure(MDAS). The stack micro-strip patch elements were used as the exciter for effectively radiating the electromagnetic power to the MDAS over the broadband, and finite metallic disk array elements - which give the role of a director for shaping the antenna beam with the high gain - were finitely and periodically layered onto it. The efficient power coupling between the exciter and the MDAS should be carried out in such a way that the proposed antenna has a high gain characteristic. The design parameters of the exciter and the MDAS should be optimized together to meet the required specifications to meet the required specifications. In this study, a shaped-beam antenna with high gain was optimally designed under the operating conditions with a linear polarization and the frequency band of $9.6{\sim}10.4\;GHz$. Two methods constructed using thin dielectric film and dielectric foam materials respectively were also proposed in order to implement the MBAS of the antenna. In particular, through the computer simulation process, the electrical performance variations of the antenna with the MDAS realized by the thin dielectric film materials were shown according to the number of disk array elements in the stack layer. Two kinds of antenna breadboard with the MDAS realized with the thin dielectric film and dielectric foam materials were fabricated, but experimentation was conducted only on the antenna breadboard(Type 1) with the MDAS realized with the thin dielectric film materials according to the number of disk array elements in the stack layer in order to compare it with the electrical performance variations obtained during the simulation. The measured antenna gain performance was found to be in good agreement with the simulated one, and showed the periodicity of the antenna gain variations according to the stack layer number of the disk array elements. The electrical performance of the Type 1 antenna was measured at the center frequency of 10 GHz. As the disk away elements became the ten stacks, a maximum antenna gain of 15.65 dBi was obtained, and the measured return loss was not less than 11.4 dB within the operating band. Therefore, a 5 dB gain improvement of the Type 1 antenna can be obtained by the MDAS that is excited by the stack microstrip patch elements. As the disk array elements became the twelve stacks, the antenna gain of the Type 1 was measured to be 1.35 dB more than the antenna gain of the Type 2 by the outer dielectric ring effect, and the 3 dB beam widths measured from the two antenna breadboards were about $28^{\circ}$ and $36^{\circ}$ respectively.

Finite element dynamic analysis of laminated composite shell structures considering geometric nonlinear effects (기하학적 비선형 효과를 고려한 복합재료 적층 쉘 구조의 유한요소 동적 해석)

  • Lee, Sang-Youl
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.14 no.11
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    • pp.5979-5986
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    • 2013
  • This study carried out a geometrical nonlinear dynamic analysis of laminated composite shell structures. Based on the first-order shear deformation shell theory and nonlinear formulation of Sanders, the Newmark method and Newton-Raphson iteration are used for dynamic solution considering nonlinear effects. The effects of radius, fiber angles, and layup sequences on the nonlinear dynamic response for various parameters are studied using a nonlinear dynamic finite element program developed for this study. The several numerical results were in good agreement with those reported by other investigators for square composite plates, and the new results reported in this paper show the significant interactions between the radius, fiber angles and layup sequence in the laminate. Key observation points are discussed and a brief design guideline of laminated composite shells is given.

헬리컬 및 직각 적층두께를 고려한 알루미늄-복합재료 압력용기의 최적설계

  • 이동건;윤영복;신돈수;하성규
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • pp.19-19
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    • 1998
  • 라이너를 포함한 필라멘트 와인딩 복합재 압력용기의 성능향상을 위한 효율적인 구조최적 설계방안을 제시하였다. 이를 위해 온도효과가 고려된 비선형 유한요소법을 이용하여 각 층에서의 응력해석과 파손해석을 수행하였다. 또한 설계변수로 라이너의 두께와 헬리컬 적층두께, 실린더를 따라 변하는 직각 적층두께를 설정하였다. 모든 설계변수들에 대한 강도비 민감도를 유도하였으며 헬리컬 적층두께에 대한 강도비 민감도를 유지하기 위해 측지 등장력 돔설계 방법을 고려하였다. 구조 최적설계결과, 실린더를 따라 직각 적층두께를 최적으로 분포시켜 강성을 효과적으로 배열하였으므로 적층두께를 일정하게 고려한 경우보다 더 경량화 시킬 수 있었다.

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Buckling Load and Mode Analysis of Symmetric Multi-laminated Cylinders with Elliptical Cross-section (다층 대칭배열된 타원형 적층관의 좌굴하중 및 모드해석)

  • Chun, Kyoung Sik;Son, Byung Jik;Ji, Hyo Seon
    • Journal of The Korean Society of Civil Engineers
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    • v.26 no.3A
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    • pp.457-464
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    • 2006
  • Fiber-reinforced composite materials due to their high specific strength, high stiffness and light weight are becoming increasingly used in many engineering industry, especially in the aerospace, marin and civil, etc. In this paper, the buckling load and mode shapes of composite laminates with elliptical cross-section including transverse shear deformations are analyzed. For solving this problems, a versatile flat shell element has been developed by combining a membrane element with drilling degree-of-freedom and a plate bending element. Also, an improved shell element has been established by the combined use of the addition of enhanced assumed strain and the substitute shear strain fields. The combined influence of shell geometry and elliptical cross-sectional parameter, fiber angle, and lay-up on the buckling loads of elliptical cylinder is examined. The critical buckling loads and mode shapes analyzed here may serve as a benchmark for future investigations.

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Static Bending Strength Performances of Hybrid Laminated Woods Composed of Wood-Wood Based Boards (목재와 목질보드 복합적층재의 휨강도성능)

  • Park, Han-Min;Moon, Sung-Jae;Choi, Yoon-Eun;Park, Jung-Hwan;Byeon, Hee-Seop
    • Journal of the Korean Wood Science and Technology
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    • v.37 no.6
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    • pp.546-555
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    • 2009
  • To study an effective use of woods, three-ply hybrid laminated woods instead of crosslaminated woods which are composed of spruce in the face and three kinds of wood-based boards (MDF, PB, OSB) in the core were manufactured, and the effect of constitution elements for the core laminae on bending strength performances was investigated. Bending modulus of elasticity (MOE) of hybrid laminated woods had the highest values for the hybrid laminated wood types arranging OSB laminae in the core, and had the lowest values for those arranging MDF laminae in the core. These values were higher than those of various cross-laminated woods. The estimated bending MOEs of the hybrid laminated woods which were composed of perpendicular-direction lamina of spruce in the faces were similar to their measured values, regardless of wood-based boards in the core. However, those of the hybrid laminated woods which were composed of parallel-direction lamina of spruce in the faces had much higher values than those of their measured values, and it was necessary to revise the measured values. Bending modulus of rupture (MOR) of the hybird laminated woods had the highest value for those arranging OSB laminae in the core, and had the lowest values for those arranging PB laminae in the core unlike the bending MOE. By hybrid laminating, the anisotropy of bending strength performances was markedly decreased, and the differences of strength performances among wood-based boards were also considerably decreased.

Low-Velocity Impact Response of Hybrid Laminated Composite Plate (혼합적층된 복합재료평판의 저속충격응답)

  • Lee, Young-Shin;Kang, Kun-Hee;Park, Oung
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.15 no.3
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    • pp.713-722
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    • 1991
  • 본 연구에서는 graphite/epoxy와 glass/epoxy 그리고 graphite/epoxy와 kevl- ar/epoxy의 혼합적층된 복합재료 평판의 저속충격에 대한 응답을 유한요소 모델을 사 용하여 수치해석 한후, 각각의 단일적층판들의 결과와 비교하였으며, 이때의 접촉력 관계식은 Yang과 Sun이 제안한 수정된 접촉법칙을 이용하였다. 또한, 수치해석 결과 에서의 충격자의 속도변화로써 혼합적창판 배열에 따른 에너지 흡수율을 계산하였고, 이를 충격특성이 취약한 graphite/epoxy 단일 적층판의 결과와 비교 고찰하였다.

A Statistical Study of Effective Properties due to Fiber Tow Misalignment and Thickness Change for Plain Weave Textile Composites (섬유다발 배열 및 적층수에 따른 평직복합재료 등가물성치의 변화에 관한 통계적 연구)

  • 우경식;서영욱
    • Composites Research
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    • v.13 no.6
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    • pp.63-72
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    • 2000
  • In this paper, statistical treatments of effective properties for plain weave textile composites were presented. Configurations up to 32 layers with varied stacking phase shifts were considered. Effective properties were calculated by numerical simulation in which uni-axial tensile and shear load were applied at unit cell. Sample analysis was utilized to consider the inherent randomness in the phase shift and the results were treated statistically. It was found that effective properties were dependent on stacking phase shifts for thin plain weave textile composites. The distribution of $E_{xx}$ and $V_{xy}$ were skewed and the range of possible values was relatively large. As the number of layers increased, however, the distribution width became narrower and mean values converged. In contrast, $G_{xy}$ was not affected by phase shifts and thickness changes.

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Impedance and Mutual Coupling Characteristics of a Probe-Fed Stacked Circular Microstrip Two-Element Array Antenna (Probe로 급전되는 적층형 원형 마이크로스트립 2소자 배열 안테나의 임피던스 및 상호 결합 특성)

  • 이면주;남상욱
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.18 no.11
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    • pp.1767-1773
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    • 1993
  • In this paper, the coupling characteristics as well as the self and the mutual Impedance of a two-element probe-fed stacked circular microstrip array antennas are presented. A full wave analysis for the structure is performed In the spectral domain using the vector Hankel transform(VHT). Also, we presented measured results for the impedance, the coupling characteristics of the antenna and the variation of the coupling with the distance between the two elements. Finally, the calculated and measured results are shown to agree well wlth each other through comparisons.

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