• Title/Summary/Keyword: Laminar composites

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Thermoelastic effect on inter-laminar embedded delamination characteristics in Spar Wingskin Joints made with laminated FRP composites

  • Mishra, P.K.;Pradhan, A.K.;Pandit, M.K.;Panda, S.K.
    • Steel and Composite Structures
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    • v.35 no.3
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    • pp.439-447
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    • 2020
  • This paper presents two sets of full three-dimensional thermoelastic finite element analyses of superimposed thermo-mechanically loaded Spar Wingskin Joints made with laminated Graphite Fiber Reinforced Plastic composites. The study emphasizes the influence of residual thermal stresses and material anisotropy on the inter-laminar delamination behavior of the joint structure. The delamination has been pre-embedded at the most likely location, i.e., in resin layer between the top and next ply of the fiber reinforced plastic laminated wingskin and near the spar overlap end. Multi-Point Constraint finite elements have been made use of at the vicinity of the delamination fronts. This helps in simulating the growth of the embedded delamination at both ends. The inter-laminar thermoelastic peel and shear stresses responsible for causing delamination damage due to a combined thermal and a static loading have been evaluated. Strain energy release rate components corresponding to the Mode I (opening), Mode II (sliding) and Mode III (tearing) of delamination are determined using the principle of Virtual Crack Closure Technique. These are seen to be different and non-self-similar at the two fronts of the embedded delamination. Residual stresses developed due to the thermoelastic anisotropy of the laminae are found to strongly influence the delamination onset and propagation characteristics, which have been reflected by the asymmetries in the nature of energy release rate plots and their significant variation along the delamination front.

Effects of salt water environment on the mechanical behavior of composites (복합재료의 기계적 거동에 염수환경이 미치는 영향에 관한 연구)

  • Moon, Jin-Bum;Kim, Soo-Hyun;Kim, Chun-Gon
    • Composites Research
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    • v.23 no.1
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    • pp.44-50
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    • 2010
  • In this paper, two different experiments, namely, salt water spray and salt water immersion, were performed to reproduce the contact of composites with the seawater for three kinds of woven fabric composite material systems which would be used for the WIG(wing in ground effect)craft. After aging 140 days in the salt water environment, material properties of carbon/epoxy and glass/epoxy composite such as tensile, compressive and shear stiffness and strength, and inter-laminar shear strength (ILSS) were measured. By comparing baseline material properties with degraded ones, the effects of the salt water environment on the composite mechanical properties were evaluated. From the experiments, it was confirmed that the difference in aging conditions had very small influence on composite properties. And it was found that tensile strength of carbon/epoxy composites showed little degradation, but much more degradation was observed in glass/epoxy composites. And large degradations on matrix dominant properties were observed. The salt water could damage the fiber-matrix interface, matrix properties and the glass fiber.

Fiber Loading Effect on the Interlaminar, Mechanical, and Thermal Properties of Novel Lyocell/Poly(butylene succinate) Biocomposites (새로운 라이오셀/poly(butylene succinate) 바이오복합재료의 층간전단, 기계적, 열적 특성에 미치는 섬유함량의 영향)

  • Lee, Jae Young;Kim, Jin Myung;Cho, Donghwan;Park, Jong Kyoo
    • Journal of Adhesion and Interface
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    • v.10 no.2
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    • pp.106-112
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    • 2009
  • In the present work, novel biocomposites made with biodegradable Lyocell woven fabrics and poly (butylene succinate) were successfully fabricated for the first time. Lyocell/poly(butylene succinate) biocomposites with different fiber loadings of 0, 30, 40, 50 and 60 wt% were prepared by compression molding with a sheet interleaving manner. The effect of Lyocell fabric loading on the interlaminar shear strength, tensile and flexural properties, heat deflection temperature, thermal expansion behavior, and thermal stability of the biocomposites was investigated. The properties strongly depended on the fabric loading and the results were consistent with each other. It was demonstrated that the Lyocell fabrics played a remarkable role in improving the properties of poly(butylene succinate) resin by incorporating the fabrics into the resin. The greatest inter-laminar, tensile, flexural and thermal properties of the biocomposites were obtained with Lyocell fabrics of 50% by weight.

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Effect of Fabricating Temperature on the Mechanical Properties of Spread Carbon Fiber Fabric Composites (스프레드 탄소섬유 직물 복합재료의 성형온도에 따른 기계적 특성에 관한 연구)

  • Eun, Jong Hyun;Gwak, Jae Won;Kim, Ki Jung;Kim, Min Seong;Sung, Sun Min;Choi, Bo Kyoung;Kim, Dong Hyun;Lee, Joon Seok
    • Composites Research
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    • v.33 no.3
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    • pp.161-168
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    • 2020
  • In this paper, we have studied the mechanical properties of thermoplastic carbon fiber fabric composites with spread technology and compression molding temperature were investigated. Carbon fiber reinforcement composites were fabricated using commercial carbon fiber fabrics and spread carbon fiber fabrics. Mechanical properties of the commercial carbon fiber composites (CCFC) and spread carbon fiber composites (SCFC) according to compression molding temperatures were investigated. Thermal properties of the polypropylene film were examined by rheometer, differential scanning calorimetry, thermal gravimetric analysis. Tensile, flexural and Inter-laminar shear test. Commercial carbon fiber reinforcement composites and spread carbon fiber composites were fabricated at 200~240℃ above the melting temperature of the polypropylene film. Impregnation properties according to compression molding temperature of the polypropylene film were investigated by scanning electron microscopy. As a result, as the compression molding temperature was increased, the viscosity of the polypropylene film was decreased. The mechanical properties of the compression molding temperature of 230℃ spread carbon fiber composite was superior.

Hygrothermal analysis of laminated composites using C0 FE model based on higher order zigzag theory

  • Singh, S.K.;Chakrabarti, A.
    • Steel and Composite Structures
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    • v.23 no.1
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    • pp.41-51
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    • 2017
  • A $C^0$ FE model developed based on an efficient higher order zigzag theory is used for hygrothermal analysis of laminated composite plates. The $C^0$ FE model satisfies the inter-laminar shear stress continuity at the interfaces and zero transverse shear stress conditions at plate top and bottom. In this model the first derivatives of transverse displacement have been treated as independent variables to circumvent the problem of $C^1$ continuity associated with the above plate theory. In the present theory the above mentioned $C^0$ continuity of the present element is compensated in the stiffness matrix formulation by using penalty parameter approach. In order to avoid stress oscillations observed in the displacement based finite element, the stress field derived from temperature/moisture fields (initial strains) must be consistent with total strain field. Special steps are introduced by field consistent approach (e.g., sampling at gauss points) to compensate this problem. A nine noded $C^0$ continuous isoparametric element is used in the proposed FE model. Comparison of present numerical results with other existing solutions shows that the proposed FE model is efficient, accurate and free of locking.

Microstructures of Multi-layer Ce-TZP/Ce-TZP-$Al_2$$O_3$Composites (Ce-TZP/Ce-TZP-$Al_2$$O_3$다층구조 복합체의 미세구조)

  • 황규홍;백인찬;이종국
    • Journal of the Korean Ceramic Society
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    • v.38 no.5
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    • pp.418-423
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    • 2001
  • 16 mole%의 CeO$_2$가 고용된 Ce-TZP 소결체 사이에 140~240$mu extrm{m}$ 두께의 Ce-TZP-5~30 vol% $Al_2$O$_3$중간층이 삽입된 층상복합체를 분말건식가압성형법에 의해 제조하였다. 소결온도는 $Al_2$O$_3$가 5~30 vol.% 첨가될 때 90% 이상의 소결밀도를 얻을 수 있도록 1$600^{\circ}C$로 정하였다. 이러한 3층 복합체에서 바깥의 Ce-TZP 지역에서의 파괴 형태는 입내파괴를 보여주었지만 $Al_2$O$_3$가 함유된 중간층에서는 입계파괴가 전이되면서 인성증가를 보여주었다. 이러한 층상 복합체의 경우 중간 층에 들어가는 Ce-TZP 중의 $Al_2$O$_3$함량이 30 vol.% 정도에 이르면 층간의 서로 다른 소결밀도 및 수축율, 열팽창계수 때문에 층간 소결 결함이 생겨 층간에서 균열의 전파가 큰 영향을 받음을 알 수 있었다. 반면 중간층의 $Al_2$O$_3$함량이 적을 경우 층간 결함이 생기지 않아 층간에서 균열의 전파가 별 영향을 받지 않음을 알 수 있었다.

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Dynamic Failure Behavior of Ceramic/Fiber-Reinforced Composites under High Speed Impact Loading (고속충격에 의한 세라믹/섬유강화 복합재료의 동적파손 거동)

  • Kim, Hui-Jae;Yuk, Jong-Il;Lee, Seung-Gu
    • Korean Journal of Materials Research
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    • v.7 no.9
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    • pp.795-804
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    • 1997
  • 전면재를 알루미나, 후면재를 Kevlar또는 S-2 유리 섬유강화 복합재료로 접합한 이종재료 장갑에 대하여 알루미나의 두께 변화와 복합재료의 적층구조에 따른 고속충격 특성 변화에 대하여 연구하였다. 또한 시험재료의 동적 관통현상을 분석하기 위하여 고속촬영기법이 이용되었다. 시험결과, 전면재인 알루미나는 충격탄자 직경의 80% 상당하는 두께(본 실험에서는 6nm)인 경우 양호한 방탄성능을 보였다. 후면재인 복합재료는 섬유를 alternating 주조로 적층한 경우가 laminar구조로 적층한 것에 비하여 더 우수한 방탄성능을 나타내었다.

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Impact Resistance of Composite Laminates Manufactured by New z-Pinning Technique (새로운 z-피닝 기술로 제작된 복합적층판의 내충격 특성)

  • Choi, Ik-Hyeon;Ahn, Seok-Min;Yeom, Chan-Hong;Hwang, In-Hee;Lee, Dae-Sung
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.37 no.7
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    • pp.693-700
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    • 2009
  • In this paper, conventional z-pinning technology which can be used to reinforce inter-laminar property of laminated composites is introduced and new z-pinning technique recently proposed by author is also introduced. On some trial specimens manufactured by the new z-pinning technique, the low-velocity impact test was performed and impact damage area was measured. Similar impact test was performed on normal composite laminate specimens and those test results were compared to each other. Consequently, it can be seen that the new z-pinning technique is more useful in applying to mass production of z-pinned composite laminate structures than the conventional techniques and some clear improvement on impact resistance of z-pinned composite laminates manufactured by the new z-pinning technique is observed.

Comparative Evaluation of Manufacturing Properties of Carbon Fiber Reinforced Thermoplastic Polymer (CFRTP) according to Nanofiller Type (나노필러 종류에 따른 열가소성 탄소 섬유강화 복합재료의 제작 물성 비교 평가)

  • Jun Ha Park;Soon Ho Yoon;Minkook Kim
    • Composites Research
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    • v.37 no.3
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    • pp.186-189
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    • 2024
  • This study compared and evaluated the mechanical properties of carbon fiber reinforced thermoplastic polymer (CFRTP) mixed with nanofillers. After mixing various nanofillers such as Multi-wall carbon nanotube (MWCNT), Silicon oxide, Core shell rubber, and Aramid nanofiber with Polyamide 6 (PA6) resin, this is used as a matrix to create a carbon fiber reinforced composite material (CFRP) was manufactured and its physical properties were measured. Depending on the type and mixing ratio of nanofiller, tensile strength, inter-laminar shear strength (ILSS), and Izod impact strength were measured. In terms of tensile strength and impact strength, the highest values were obtained when mixing core shell rubber, however the ILSS was optimal when mixing less than 1 wt.% of silicon oxide.