• Title/Summary/Keyword: secondary bonding

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Effect of Surface Treatment on Adhesive Bonding Strengh of Composite Material for Cryogenic Application (극저온용 복합재료의 접착부 강도에 미치는 표면처리 효과에 대한 연구)

  • Ahn, Myoung-Ho;So, Yong-Shin;Park, Dong-Hwan
    • Proceedings of the KWS Conference
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    • 2010.05a
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    • pp.28-28
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    • 2010
  • The secondary barrier of cargo containment for membrane LNG tank is composed of composite materials such as rigid triplex (rigid secondary barrier, RSB) and flexible triplex (flexible secondary barrier, FSB). RSB and FSB are adhered to each other using an epoxy adherent and the quality of the secondary barrier depends on the bonding strength between them. The bonding strength between RSB and FSB is greatly influenced by the surface condition of RSB prior to joining. In this study, the effect of surface condition prior to joining on the joint strength and the fracture mode occurred between RSB and FSB have been examined in order to establish a proper surface treatment method for improving the bonding strength at the temperature of $-170^{\circ}C$.

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A Study on the Curing Method to Improve Bonding Strength of Aluminum/CFRP Composites (알루미늄/CFRP 복합재의 접착강도 향상을 위한 경화방법에 관한 연구)

  • 이경엽;양준호;최낙삼
    • Transactions of the Korean Society of Automotive Engineers
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    • v.10 no.3
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    • pp.130-135
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    • 2002
  • This study investigates the effect of curing method on the bonding strength of aluminum/CFRP composites. The surface of aluminum panel was treated by DC plasma. Lap shear tests and T-peel tests were performed based on the procedure of ASTM 906-94a and ASTMD1876-95, respectively. Test samples were fabricated by using the co-curing method and the secondary curing method. The results showed that the shear strength of test samples made by the co-curing method was 2.5 times greater than that of test samples made by the secondary curing method. The T-peel strength of the co-curing method case was almost 2 times greater than that of the secondary curing method case.

Fabrication and Evaluation of Composite Panel with Hat-shaped Stiffeners (모자(Hat)형 보강재를 가진 복합재 패널의 제작과 평가)

  • Kim, Geon-Hui;Lim, Do-Wan;Choi, Jin-Ho;Kweon, Jin-Hwe;Lee, Tae-Joo;Song, Min-Hwan;Shin, Sang-Joon
    • Composites Research
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    • v.23 no.2
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    • pp.31-39
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    • 2010
  • In this paper, composite panels with hat-shaped stiffeners were made using the co-curing, co-bonding and secondary bonding methods. Co-curing is a manufacturing method in which the hat part and the plate are cured simultaneously in a manner that is more cost effective than other methods. Co-bonding is a method in which the stacked prepregs are cured with other cured parts, and secondary bonding is a method in which cured parts are bonded together using an adhesive. A rubber mold was manufactured for co-curing of composite panel with hat-shaped stiffeners, and finite element analyses were done to evaluate the expanding pressure of the rubber mold consistent with the curing temperature. The manufactured panels were also evaluated using a 3-D measurement tester and an ultrasonic tester. Pull-off tests were performed to evaluate their mechanical properties.

Experimental Debonding Failure Behaviors of Composite Skin-Stiffener Bonded Specimens (복합재료 스킨-보강재 접합 시편의 파손 특성에 대한 시험 연구)

  • Kim, Kwang-Soo;An, Jae-Mo;Jang, Young-Soon;Yi, Yeong-Moo
    • Composites Research
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    • v.20 no.6
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    • pp.8-14
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    • 2007
  • Debonding failure characteristics of the composite skin-stiffener specimens were experimentally investigated. The influences of bonding methods, types of stiffener shape and various secondary bonding parameters were evaluated. Present test results combined with the previous test results[1] showed that the failure displacement of the skin-stiffener specimens well evaluates the skin-stiffener debonding failure strength of the composite stiffened panels. The specimens with an open type stiffener had lower bending stiffness and larger failure displacement than those with a closed type stiffener. Secondary bonding and co-curing with adhesive had better failure strength than co-curing without adhesive film. Secondary bonded specimens failed by adhesive failure and co-cured specimens failed by delamination failure. As the bondline thickness was thinner, the skin-stiffener specimens had higher failure strength. The fillets had no influence on failure strength of the specimens. The influence of the surface roughness was shown according to types of stiffener shape.

Failure Mode and Strength of Unidirectional Composite Single Lap Bonded Joints I. Experiments (일방향 복합재료 Single Lap접합 조인트의 파손 모드 및 강도 I. 실험)

  • Kim Kwang-Soo;Yoo Jae-Seok;An Jae-Mo;Jang Young-Soon
    • Composites Research
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    • v.17 no.6
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    • pp.14-21
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    • 2004
  • Failure process, mode and strength of unidirectional composite single lap bonded joints were investigated experimentally with respect to bonding methods, those are, co-curing with and without adhesive and secondary bonding. The co-cured joint specimens without adhesive had the largest failure strength. Progressive failures along the adhesive layer occurred in the secondary bonded specimens. In the co-cured specimens with adhesive film which had better material strength and adhesion performance, delamination failure occurred and the joint strengths were less than those of secondary bonded specimens. Delamination failure did not occur in the secondary bonded specimens because of earlier crack growth and progressive failure in the adhesive layer. Therefore, failure strength of composite bonded Joints were not always proportionate to material strength and adhesion performance of the adhesive due to the weakness of delamination in composite materials. The effects of surface roughness, bondline thickness and fillets were also studied on secondary bonded specimens.

Composite Iso-Grid Panel Production and Buckling Test (복합재 Iso-Grid 패널 제작 및 좌굴시험)

  • Yoo Jae-Seok;Kim Kwang-Soo;Jang Young-Soon
    • Proceedings of the Korean Society For Composite Materials Conference
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    • 2004.10a
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    • pp.51-55
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    • 2004
  • A composite Iso-grid panel is manufactured and tested by compressive load. Vertical stringers and side stringers are joined with skin by secondary bonding using a liquid type adhesive. Bonding fixtures were developed to attach the stringers to skin. A-scan was done for inspection of secondary bonding region. The out of displacement field is visualized by shadow moire system. The strain and vertical displacement are measured by strain gages and L VDT (Linear Variable Differential Transformer). A local buckling is occurred at all grid sections. After that, the final failure is occurred. The strain of side stringer is much less than that of vertical stringer and skin. Due to the side stringer, the local buckling is delayed. Therefore the ratio of the first buckling to failure load is greater than that of vertical stringer stiffened panel.

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Fracture Characteristics Unidirectional Composite Single-Lap Bonded Joints (일방향 복합재료 single-lap 접합 조인트의 파괴 특성)

  • Kim Kwang-Soo;Yoo Jae-Seok;Jang Young-Soo;Yi Yeong-Moo
    • Proceedings of the Korean Society For Composite Materials Conference
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    • 2004.04a
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    • pp.232-236
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    • 2004
  • The fracture characteristics of unidirectional composite single-lap bonded joints were investigated experimentally and numerically. The effects of bonding method, surface roughness, bondline thickness and the existence of fillet on the failure characteristics and strength of bonded single-lap joints were evaluated experimentally. The failure process, failure mode and the behavior of load-displacement curve was apparently different according to bonding method. The failure load of the specimen co-cured without adhesive was definitely superior to other types of specimens but the specimens co-cured with adhesive film had a less strength than secondary bonded specimens. In the secondary bonded specimens, the lower value of surface roughness and existence of fillet improved the strength of specimens. The strain energy release rates calculated by geometric nonlinear finite element analyses and Virtual Crack Closure Technique for the secondary bonded specimens considering the three types of initial cracks - comer crack, edge crack and delamination crack - were consistent with the test results.

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Debonding and Postbuckling Failure Characteristics of Composite Stiffened Panels (복합재 보강패널의 분리파손 및 좌굴 후 강도 특성)

  • Kim, Kwang-Soo;Yoo, Jae-Seok;An, Jae-Mo;Jang, Young-Soon;Yi, Yeong-Moo
    • Proceedings of the Korean Society For Composite Materials Conference
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    • 2005.04a
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    • pp.59-63
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    • 2005
  • Compression tests were performed for six types of hat stiffened composite panels with different bonding methods and stiffener section shapes. Six panels showed similar behaviors in buckling and post-buckling region before a skin-stiffener separation failure occurred. The skin-stiffener separation failures occurred in the panels with closed type stiffeners regardless of bonding methods, but not in the panels with open type stiffeners. The separation failures not only reduced the postbuckling strength but also changed buckling mode and postbuckling stiffness. All the separation failures were initiated at the stiffener flange edges closest to skin buckling crests. The co-cured or secondary bonded panels with open type stiffeners had the largest structural performance. Because the post-buckling strength and performance of the composite stiffened panels are reduced by the separation failure, it is important to find bonding methods, stiffener types and manufacturing parameters for preventing of the separation failure.

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An Experimental Study on the Strength of Single-Lap Bonded Joints of Carbon Composite and Aluminum (탄소 복합재와 알루미늄 이종재료 단일겹침 접착 체결부의 강도에 관한 실험 연구)

  • Kim, Tae-Hwan;Lee, Chang-Jae;Choi, Jin-Ho;Kweon, Jin-Hwe
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.35 no.3
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    • pp.204-211
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    • 2007
  • Experiments were conducted to investigate the failure and strengths of carbon composite-to-aluminum single-lap bonded joints with 5 different bonding lengths. Joint specimens were fabricated to have secondary bonding of laminate and aluminum with a film type adhesive, FM73m. Tested joints have the bonding strengths between the values of aluminum-to-aluminum joints and composite-to-composite joints. In the joints with bonding length-to-width ratio smaller than 1, the strength decreases as the bonding length increases. In the joints with the ratio larger than 1, however, the strength converges to a constant value. Final failure mode of all the specimens was delamination. To use the maximum strength of the adhesive, it is important to design the joint to have strong resistance to delamination.

Fabrication and Evaluation of Composite Panel with L-shaped Stiffeners (L-형 보강재를 가진 복합재 패널의 제작과 평가)

  • Yun, Jong-Hwa;Choi, Jin-Ho;Kweon, Jin-Hwe
    • Composites Research
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    • v.26 no.2
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    • pp.99-104
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    • 2013
  • The design of composite joint is important research area because they are often the weakest areas in composite structures. In this paper, the specimens with three paste thickness (0.2 mm, 0.6 mm, 4 mm) were manufactured in secondary bonding method and tested in two different loading direction condition. Also, the failure index of the L-type stiffener was calculated by the finite element method and compared with experimental results.