• Title, Summary, Keyword: Composite Patch

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A Study on the fatigue Behavior of Aluminum Repaired by Graphite/Epoxy Composite - Pretreatment Effect of Aluminum (탄소섬유/에폭시 복합재로 보수된 알루미늄의 피로특성에 대한 연구 -알루미늄 표면처리 효과)

  • 김만태;이경엽
    • Journal of the Korean Society for Precision Engineering
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    • v.21 no.11
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    • pp.149-154
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    • 2004
  • For a present study, we investigated fatigue behavior of cracked aluminum repaired by unidirectional graphite/epoxy composite material. Three different specimens were used in the fatigue tests: cracked aluminum, cracked aluminum repaired by graphite/epoxy composite patch, and plasma-treated aluminum repaired by graphite/epoxy composite patch. The surface of the aluminum was treated using a DC plasma. The results showed that the fatigue crack growth behavior of cracked aluminum was significantly improved by repairing the cracked area with a composite patch. Specifically, the specimen repaired by composite patch showed about 300% more fatigue lift than the cracked aluminum. In particular, the plasma-treated aluminum repaired by composite patch showed almost 12 % more fatigue life than the cracked aluminum repaired by graphite/epoxy composite patch. The increased fatigue life of plasma-treated case was attributed to the surface roughness of aluminum by plasma treatment.

A Study on Fatigue Crack Growth of Composite Patching Repaired on Cracked Thick Plate (복합재료 보강재로 보수되어진 균열을 가진 두꺼운 평판의 피로균열 성장에 관한 연구)

  • Jeong, Gi-Hyeon;Yang, Won-Ho;Go, Myeong-Hun
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.25 no.12
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    • pp.2070-2077
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    • 2001
  • An experimental investigation of the effect of composite patching repair was conducted to characterize the fatigue crack growth behavior in thick A16061-T6 (6mm) panels with single bonded patch by fiber reinforced composite patch. Four patch lengths and no patch plate were examined. An analytical procedure, involving three-dimensional finite element method having three layers to model cracked aluminum plate, epoxy by adhesive and composite Patch, is calculated the stress intensity factors. From the calculated stress intensity factors, the fatigue crack growth rates are obtained. At the single patching type, different fatigue crack growth ratios through the palate thickness were investigated by using the experimental and analytical results. The results demonstrated that there was a definite variation in fatigue life depending on the size of composite patch. While crack reached the patch end, retardation of crack growth was also revealed in the bonded repair.

FATIGUE CRACK GROWTH MONITORING OF CRACKED ALUMINUM PLATE REPAIRED WITH COMPOSITE PATCH USING EMBEDDED OPTICAL FIBER SENSORS (광섬유센서를 이용한 복합재 패치수리된 알루미늄판의 균열관찰)

  • 서대철;이정주;김상훈
    • Proceedings of the Korean Society For Composite Materials Conference
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    • pp.250-253
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    • 2001
  • Recently, based on the smart structure concept, optical fiber sensors have been increasingly applied to monitor the various engineering and civil structural components. Repairs based on adhesively bonded fiber reinforce composite patches are more structurally efficient and much less damaging to the parent structure than standard repairs based on mechanically fastened metallic patches. As a result of the high reinforcing efficiency of bonded patches fatigue cracks can be successfully repaired. However, when such repairs are applied to primary structures, it is needed to demonstrate that its loss can be immediately detected. This approach is based on the "smart patch" concept in which the patch system monitors its own health. The objective of this study is to evaluate the potentiality of application of transmission-type extrinsic Fabry-Perot optical fiber sensor (TEFPI) to the monitoring of crack growth behavior of composite patch repaired structures. The sensing system of TEFPI and the data reduction principle for the detection of crack detection are presented. Finally, experimental results from the tests of center-cracked-tension aluminum specimens repaired with bonded composite patch is presented and discussed.

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Numerical study of bonded composite patch repair in damaged laminate composites

  • Azzeddine, Nacira;Benkheira, Ameur;Fekih, Sidi Mohamed;Belhouari, Mohamed
    • Advances in aircraft and spacecraft science
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    • v.7 no.2
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    • pp.151-168
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    • 2020
  • The present study deals with the repair of composite structures by bonding composite patches. The composite structure is a carbon/epoxy laminate with stacking sequence [45/-45/0/90]S. The damaged zone is simulated by a central crack and repaired by bonding symmetrical composite patches. The repair is carried out using composite patches laminated from the same elemental folds as those of the cracked specimen. Three-dimensional finite element method is used to determine the energy release rate along the front of repaired crack. The effects of the repair technique used single or double patch, the stacking sequence of the cracked composite patch and the adhesive properties were highlighted on the variations of the fracture energy in mode I and mixed mode I + II loading.

Fatigue Behavior of Cracked Al 6061-T6 Alloy Structures Repaired with Composite Patch

  • Yoon, Young-Ki;Park, Jong-Joon;Kim, Guk-Gi;Yoon, Hi-Seak
    • International Journal of Precision Engineering and Manufacturing
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    • v.2 no.3
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    • pp.5-10
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    • 2001
  • Due to the development of high-strength fibers and adhesives, it is now possible to repair cracked metallic plates by bonding reinforced patches to the plate over the crack. In this study, pre-cracked aluminum 6061-T6 alloy plates repaired with bonded carbon/epoxy composite patch are applied to investigate the effect of various patch shapes on the tensile strength and the fatigue behavior of the structure. A non-patch-boned cased and 2 type-50$\times$50, 40$\times$20 mm-composite patch-bonded cases were tested to obtain fracture loads and fatigue crack growth rate. The results showed that the patch-bonded repair improves the static strength by 17% and the fatigue life by 200% compared to non-repaired case. It means that patch-boned repair is more effective in the fatigue life. It was also revealed that the patching method along crack growth direction is more efficient in cost and weight reduction. By observing the fractography, patch-bonded repair specimens demonstrated zigzag fracture patterns compared with the non-patched specimens, which shows a typical ductile fracture.

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An Experimental Study on the Fatigue Characteristics of Silane-Treated Al/CFRP Composite Material (알루미늄의 Silane 표면처리에 따른 Al/CFRP 이종재의 피로특성)

  • 김만태;이경엽;지창헌
    • Journal of the Korean institute of surface engineering
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    • v.37 no.1
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    • pp.49-52
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    • 2004
  • In this study, we investigated the fatigue characteristics of silane-treated aluminum/CFRP composite material. Three different specimens of cracked aluminum, cracked aluminum repaired with CFRP patch, and silane-treated aluminum repaired with CFRP patch were used in the fatigue tests. Load ratio and the frequency applied in the fatigue tests were 0 and 10 Hz, respectively. The results showed that the specimen repaired by composite patch showed three times more improved fatigue life than aluminum specimen. Furthermore, the silane-treated specimen repaired by composite patch showed four times more improved fatigue life than the non-treated specimen.

A Experimental Study on the Fatigue Crack Growth Behavior of Thick Plate with Repaired Crack (보수된 균열을 가진 두꺼운 평판의 피로균열 성장 거동에 관한 실험적 연구)

  • Chung, Ki-Hyun;Yang, Won-Ho;Kim, Cheol;Sung, Ki-Deug
    • Proceedings of the KSME Conference
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    • pp.292-298
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    • 2001
  • An experimental investigation of the effect of composite patching repair was conducted to characterize the fatigue crack growth behavior in thick A16061-T6 (6mm) panels with single bonded patch by fiber reinforced composite patch. Four patch lengths and no patch plate were examined. An analytical procedure, involving three-dimensional finite element method having three layers to model cracked aluminum plate, epoxy by adhesive and composite patch, is calculated the stress intensity factors. From the calculated stress intensity factors, the fatigue crack growth rates are obtained. At the single patching type, different fatigue crack growth ratios through the plate thickness were investigated by using the experimental and analytical results. The results demonstrated that there was a definite variation in fatigue life depending on the size of composite patch. While crack reached the patch end, retardation of crack growth was also revealed in the bonded repair.

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Fracture Mechanics Analysis of Cracked Plate Repaired by Patch (I) (보강재로 보수된 균열평판의 파괴역학적 해석(I))

  • Jeong, Gi-Hyeon;Yang, Won-Ho;Jo, Myeong-Rae
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.24 no.8
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    • pp.2000-2006
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    • 2000
  • The enhancement of service life of damaged or cracked structures is currently major issue to the researchers and engineers. In order to improve the life of cracked aging aircraft structures, the repair technique which uses adhesively bonded boron/epoxy composite patches is being widely considered as a cost-effective and reliable method. This paper is to study the performance of the bonded composite patch repair of a plate containing an inclined central through-crack. A 3-dimensional finite element method having three layers to the cracked plate, composite patch and adhesive layer, is used to compute the stress intensity factor. In this paper, the reduction of stress intensity factors near the crack-tip are determined to evaluate the effects of various non-dimensional design parameter including composite patch thickness, and material properties of the composite patch and thickness of the adhesive layer, materials of patch etc., and the crack length, Finally, The problem of how to optimize the patch geometric configurations has been discussed.

Numerical analysis of interface crack problem in composite plates jointed with composite patch

  • Cetisli, Fatih;Kaman, Mete O.
    • Steel and Composite Structures
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    • v.16 no.2
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    • pp.203-220
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    • 2014
  • Stress intensity factors are numerically investigated for interfacial edge crack between two dissimilar composite plates jointed with single side composite patch. Variation of stress intensity factor under Mode I loading condition is examined for different material models and fiber orientation angles of composite plates and patch. ANSYS 12.1 finite element analysis software is used to obtain displacements of crack surfaces in the numerical solution and repaired plates are modeled in three dimensions. Obtained results are presented in the form of graphs. It is found that fiber orientation angle of composites is an effective parameter on interfacial stress intensity factor.

Analysis of Thermal Residual Stress in Composite Patches (복합재 패춰의 열잔류응력 해석)

  • 김위대;김난호
    • Proceedings of the Korean Society For Composite Materials Conference
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    • pp.63-66
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    • 2000
  • This research addresses study on thermal residual stress of a composite patch repair of the edge cracked aluminium panel of aging aircraft. Composite patch repair is an efficient and economical technique to improve the damage tolerance of cracked metallic structures. These are thermal residual stresses due to the mismatch of coefficient of thermal expansion, and these are affected by the curing cycle of patch specimen. In this study, three curing cycles were selected for F.E. analysis. This study features the effect on composite patch and aluminum by thermal residual stress during crack propagation in aluminum plate.

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