• Title/Summary/Keyword: 복합재 격자 구조

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Development and Evaluation of Large Scale Composite Lattice Structures (대형 복합재 격자구조체 개발 및 평가)

  • Kim, Donggeon;Doh, Youngdae;Kim, Gensang;Kim, Myungjoo;Lee, Sangwoo
    • Journal of the Korean Society of Propulsion Engineers
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    • v.25 no.6
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    • pp.74-86
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    • 2021
  • The composite lattice structure is a structure that supports the required load with the minimum weight and thickness. Composite lattice structure is manufactured by the filament winding process using impregnating high-strength carbon fiber with an epoxy resin. Filament winding process can laminate and manufacture only structurally necessary parts, composite lattice structure can be applied to aircraft fuselages, satellite and launch vehicles, and guided weapons to maximize weight reduction. In this paper, the development and evaluation of the composite lattice structure corresponding to the entire process from design, analysis, fabrication, and evaluation of large-scale cylindrical and conical composites lattice structure were performed. To be applicable to actual projectiles and guided weapons, we developed a cylindrical lattice structure with a diameter of 2,600 mm and a length of 2,000 mm, and a conical lattice structure with an upper diameter of 1,300 mm, a lower diameter of 2,500 mm, and a length of 900 mm. The performance of the developed composite lattice structure was evaluated through a load test.

Study on Evaluation Method of Structural Integrity of Cylindrical Composite Lattice Structures (원통형 복합재 격자구조체의 구조안전성 평가 기법 연구)

  • Im, Jae-Moon;Kang, Seung-Gu;Shin, Kwang-Bok;Lee, Sang-Woo
    • Composites Research
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    • v.30 no.6
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    • pp.338-342
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    • 2017
  • In this paper, evaluation method of structural integrity of cylindrical composite lattice structures was conducted. A finite element analysis was used to evaluate the structural integrity of composite lattice structures. In order to verify the optimal finite element in the evaluation of the structural integrity, finite element models for cylindrical composite lattice structure were generated using beam, shell and solid elements. The results of the finite element analyses with the shell and solid element models showed a good agreement. However, considerable differences were found between the beam element model and the shell and solid models. This occurred because the beam element does not take into account the degradation of the mechanical properties of the non-intersection parts of cylindrical composite lattice structures. It was found that the finite element analysis of evaluation of structural integrity for cylindrical composite lattice structures have to use solid element.

Study on Application of Ultrasonic Propagation Imager for Non-destructive Evaluation of Composite Lattice Structure (복합재 격자 구조 비파괴평가를 위한 초음파전파 영상화 시스템 활용 연구)

  • Park, Jae-Yoon;Shin, Hye-Jin;Lee, Jung-Ryul
    • Composites Research
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    • v.30 no.6
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    • pp.356-364
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    • 2017
  • Composite lattice structures are tried to be used in various fields because of its benefit in physical properties. With increase of demand of the composite lattice structure, nondestructive testing technology is also required to certificate the quality of the manufactured structures. Recently, research on the development of the composite lattice structure in Republic of Korea was started and accordingly, fast and accurate non-destructive evaluation technology was needed to finalize the manufacturing process. This paper studied non-destructive testing methods for composite lattice structure using laser ultrasonic propagation imaging systems. Pulse-echo ultrasonic propagation imaging system was able to inspect a rib structure wrapped with a skin structure. To reduce the time of inspection, a band divider, which can get signal in different frequency bands at once, was developed. Its performance was proved in an aluminum sandwich panel. In addition, to increase a quality of results, curvature compensating algorithm was developed. On the other hand, guided wave ultrasonic propagation imaging system was applied to inspect delamination in a rib structure. To increase an area of inspection, multi-source ultrasonic wave propagation image was applied, and defects were successfully highlighted with variable time window amplitude mapping algorithm. These imply that ultrasonic propagation imaging systems provides fast and accurate non-destructive testing results for composite lattice structure in a stage of the manufacturing process.

Manufacturing Processes of Cylindrical Composite Lattice Structures using Filament Winding Method (필라멘트 와인딩 공법을 이용한 원통형 복합재 격자구조체 제작 공정)

  • Im, Jaemoon;Shin, Kwangbok;Lee, Sangwoo;Son, Johwa
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2017.05a
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    • pp.835-837
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    • 2017
  • In this paper, manufacturing processes of cylindrical composite lattice structures using filament winding method was described. Cylindrical composite lattice structures were manufactured in accordance with four major steps. Silicon mold of lattice shape was installed on mandrel and then continuous fiber was wound on silicon mold. After winding process, in order to ensure the same thickness for all regions, compression process was done for its intersection parts. Finally, the composite lattice structure was demoulded after curing in oven. It was found that the manufactured cylindrical composites lattice structure had 2.4% of dimensional error compared to the design requirements.

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Study on Evaluation Method of Structural Integrity for Cone-Type Composite Lattice Structures with Hexagonal Cell (육각 격자구조를 갖는 콘형 복합재 격자구조체의 구조안전성 평가 기법 연구)

  • Im, Jae-Moon;Kang, Seung-Gu;Shin, Kwang-Bok;Lee, Sang-Woo
    • Composites Research
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    • v.31 no.4
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    • pp.156-160
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    • 2018
  • In this paper, evaluation method of structural integrity for cone-type composite lattice structures with hexagonal cell was conducted. A finite element analysis was used to evaluate the structural integrity of cone-type composite lattice structure. The finite element model for evaluation of structural integrity was generated using solid element. In order to consider the difference in mechanical properties between intersection and non-intersection part, the mechanical properties were applied considering the fiber volume fraction of each part. Compression test of cone-type composite lattice structure were conducted for verification of evaluation method of structural integrity. The analysis result showed 2% errors in displacement and good agreement with test result.

Compression and Bending Test for the Stiffness of Composite Lattice Subelement (복합재 격자 구조의 강성 평가를 위한 Subelement의 압축, 굽힘 시험)

  • Jeon, Min-Hyeok;Kang, Min-Song;Kim, In-Gul;Kim, Mun-Guk;Go, Eun-Su;Lee, Sang-Woo
    • Composites Research
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    • v.30 no.6
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    • pp.331-337
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    • 2017
  • The composite lattice structures have advantages of high specific stiffness and strength and are mainly applied to the structures of launch vehicles that carry the compressive load. However, since these structures are manufactured by filament winding technology, there are some defects and voids found in the knots. For these reasons, the stiffness and strength of the lattice structures have to be compared with finite element model for predicting design load. But, the full scale test is difficult because time and space are limited and the shape of structure is complex, and hence the simple and reliable test methods for examination of stiffness are needed. In this paper, subelements of composite lattice structures were prepared and compressive and bending test were conducted for examination of stiffness of helical and hoop rib. Test methods for subelements of composite lattice structures that has curved and twisted shape were supposed and compared with finite element analysis results.

The Effect of Fiber Volume Fraction Non-uniformity in Thickness Direction on the Buckling Load of Cylindrical Composite Lattice Structures (두께 방향 섬유체적비 불균일이 원통형 복합재 격자 구조 좌굴하중에 미치는 영향)

  • Kong, Seung-Taek;Jeon, Min-Hyeok;Kim, In-Gul;Lee, Sang-Woo
    • Composites Research
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    • v.34 no.2
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    • pp.129-135
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    • 2021
  • In this paper, in order to examine the effect of fiber volume fraction non-uniformity in thickness direction on the buckling load of cylindrical composite lattice structures, we modified the equation of buckling load of the cylindrical composite lattice structures proposed by Vasiliev. The thickness of each layer of the rib was varied by fiber volume fraction, and material properties were applied differently by using the rule of mixture. Also, we performed linear buckling analysis by varying the structure size, thickness, and average value of the fiber volume fraction of finite element model. Finally, by comparing the calculation results of the buckling load of the equivalent model using the modified buckling load equation and the results of the finite element analysis, we found that the fiber volume fraction non-uniformity in thickness direction can reduce the buckling load of the cylindrical composite lattice structure.

Verification of Finite Element Model for Composite Lattice Structures through Natural Frequency Test (고유진동수 시험을 통한 복합재 격자구조체의 유한요소모델 검증)

  • Im, Jaemoon;Shin, Kwangbok;Lee, Sangwoo
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2017.05a
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    • pp.832-834
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    • 2017
  • In this paper, the finite element models for composite lattice structures were verified through natural frequency test. Finite element models of composite lattice structure were generated using beam, shell and solid element. Natural frequencies were measured using impact test method under free-boundary condition. The natural frequencies of finite element analysis for shell and solid element showed a good agreement with experimental results. But beam element did not show a good agreement with experimental results, because beam element could not consider the degradation of mechanical properties of non-intersection parts for composite lattice structure.

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Periodic Mesh Generation for Composite Structures using Polyhedral Finite Elements (다면체 유한요소를 이용한 복합재 구조의 주기 격자망 생성)

  • Sohn, Dongwoo;Park, Jong Youn;Cho, Young-Sam;Lim, Jae Hyuk;Lee, Haengsoo
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.27 no.4
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    • pp.239-245
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    • 2014
  • Finite element modeling of composite structures may be cumbersome due to complex distributions of reinforcements. In this paper, an efficient scheme is proposed that can generate periodic meshes for the composite structures. Regular meshes with hexahedral finite elements are first prepared, and the elements are then trimmed to fit external surfaces of reinforcements in the composite structures. The trimmed hexahedral finite elements located at interfaces between the matrix and the reinforcements correspond to polyhedral finite elements, which allow an arbitrary number of nodes and faces in the elements. Because the trimming process is consistently conducted by means of consistent algorithms, the elements of the reinforcements are automatically compatible with those of the matrices. With the additional consideration of periodicity of reinforcements in a representative volume element(RVE), the proposed scheme provides periodic meshes in an efficient manner, which are compatible for each pair of periodic boundaries of the RVE. Therefore, periodic boundary conditions for the RVE are enforced straightforwardly. Numerical examples demonstrate the effectiveness of the proposed scheme for finite element modeling of complex composite structures.

Shape Monitoring of Composite Cantilever Beam by Using Fiber Bragg Grating Sensors (광섬유 브래그 격자 센서를 이용한 복합재 외팔보의 형상 모니터링)

  • Lee, Kun-Ho;Kim, Dae-Hyun
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.37 no.7
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    • pp.833-839
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    • 2013
  • In this study, an experiment was performed to monitor the two-dimensional shape of a cantilever composite structure using fiber Bragg grating (FBG) sensors. To monitor the shape of a composite structure, a deflection equation developed by NASA was applied and a composite beam attached to three FBG sensors was used. In the experiment, the shape of the composite beam was successfully estimated and an error was evaluated by comparing a real deflection. The error increased with real deflection; therefore, it was compensated by using the linear relationship between the error and the real deflection. After compensating the error, the measured deflection shows good agreement with the real deflection. Finally, the experiment shows that the FBG sensor and the deflection equation are suitable for monitoring the deflection curve of the beam structure with compensation of the error.