• Title/Summary/Keyword: Composite Patch

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Analysis of the adhesive damage for different patch shapes in bonded composite repair of corroded aluminum plate

  • Mohamed, Berrahou;Bouiadjra, B. Bachir
    • Structural Engineering and Mechanics
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    • v.59 no.1
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    • pp.123-132
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    • 2016
  • Many military and commercial aging aircrafts flying beyond their design life may experience severe crack and corrosion damage, and thus lead to catastrophic failures. In this paper, were used in a finite element model to evaluate the effect of corrosion on the adhesive damage in bonded composite repair of aircraft structures. The damage zone theory was implemented in the finite element code in order to achieve this objective. In addition, the effect of the corrosion, on the repair efficiency. Four different patch shapes were chosen to analyze the adhesive damage: rectangular, trapezoidal, circular and elliptical. The modified damage zone theory was implemented in the FE code to evaluate the adhesive damage. The obtained results show that the adhesive damage localized on the level of corrosion and in the sides of patch, and the rectangular patch offers high safety it reduces considerably the risk of the adhesive failure.

Repair methods for aging aircraft and application of composite patch repair (노후항공기의 보수 방법 및 복합재 패치보수의 응용)

  • 김위대;김종진
    • Proceedings of the Korean Society For Composite Materials Conference
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    • 2002.05a
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    • pp.167-172
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    • 2002
  • During the operation of military aircraft, maintenance is divided into organizational, intermediate and depot maintenance. In the depot maintenance, after removal of major parts and removable doors, damage assessment is performed. Locating damage, charactering the damage and determining its extent, zoning the damage on the part being repaired and re-evaluation of the damaged area after damage removal. Repair joints are classified by bonded joints and bolted joints, depending on joining material. In this paper, repair method in aging aircraft is investigated and the possibility of application of copmposite patch is surveyed.

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Probabilistic elastic-plastic analysis of repaired cracks with bonded composite patch

  • Mechab, Belaid;Chama, Mourad;Kaddouri, Khacem;Slimani, Djelloul
    • Steel and Composite Structures
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    • v.20 no.6
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    • pp.1173-1182
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    • 2016
  • The objective of this work was to evaluate the ductile cracked structures with bonded composite patch used in probabilistic elastic plastic fracture mechanics subjected to tensile load. The finite element method is used to analyze the stress intensity factors for elastic case, the effect of cracks and the thickness of the patch ($e_r$) are presented for calculating the stress intensity factors. For elastic-plastic the Monte Carlo method is used to predict the distribution function of the mechanical response. According to the obtained results, we note that the stress variations are important factors influencing on the distribution function of (J/Je).

Impact of bonding defect on the tensile response of a composite patch-repaired structure: Effect of the defect position and size

  • N., Kaddouri;K., Madani;S.CH., Djebbar;M., Belhouari;R.D.S.G., Campliho
    • Structural Engineering and Mechanics
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    • v.84 no.6
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    • pp.799-811
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    • 2022
  • Adhesive bonding has seen rapid development in recent years, with emphasis to composite patch repairing processes of geometric defects in aeronautical structures. However, its use is still limited given its low resistance to climatic conditions and requirement of specialized labor to avoid fabrication induced defects, such as air bubbles, cracks, and cavities. This work aims to numerically analyze, by the finite element method, the failure behavior of a damaged plate, in the form of a bonding defect, and repaired by an adhesively bonded composite patch. The position and size of the defect were studied. The results of the numerical analysis clearly showed that the position of the defect in the adhesive layer has a large effect on the value of J-Integral. The reduction in the value of J-Integral is also related to the composite stacking sequence which, according to the mechanical properties of the ply, provides better load transfer from the plate to the repair piece through the adhesive. In addition, the increase in the applied load significantly affects the value of the J-Integral at the crack tip in the presence of a bonding defect, even for small dimensions, by reducing the load transfer.

Residual Deformation Induced by the Repair of Composite Shell Structures (복합재료 쉘 구조물의 수리 시 발생하는 잔류변형)

  • 최항석;정의승;이수용
    • Composites Research
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    • v.12 no.4
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    • pp.17-24
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    • 1999
  • Finite element analysis and experiment are performed to investigate residual deformation induced by the repair of composite shell structures using a prepreg patch method. The finite element program is developed on the basis of a three-dimensional degenerated shell element and the first order shear deformation theory. The results analyzed for the laminated shell with free boundary conditions are compared with strains measured during the prepreg patch repair. Final residual stresses occur greatly near the patch when the laminated shell with all edges clamped is repaired using the prepreg patch. Stacking sequences of the laminated shell and patch affect significantly the residual stresses which occur even if they are the same.

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The failure analysis of patch bonded repair on Al 6061-T6 alloy structures with cracked bolt hole (볼트 균열 홀을 갖는 알루미늄 6061-T6 합금의 패치 본딩 보수/보강 부위에 대한 파괴역학적 해석에 관한 연구)

  • Yoon, Young-Ki;Kim, Guk-Gi;Park, Jong-Jun;Yoon, Hi-Seak
    • Proceedings of the KSME Conference
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    • 2000.04a
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    • pp.148-152
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    • 2000
  • The aluminum alloy 6061-T6 has been successfully used in structural applications especially the pressure vessel of the Advanced Neutron Source research reactor. And aluminum alloys, including 6061-T6, have a face-centered-cubic crystals structure. Under normal circumstances face-centered-cubic crystal structures do not exhibit cleavage fractures even at very lo9w temperatures. In aluminum-based structures, plates frequently find use as connecting links. Mechanical fasteners are often utilized in instances where ease of application, familiarity with fabrication processes, and severe dynamic loading are of concern. Plates frequently find use as connecting elements in structures built from aluminum alloys. Many structural elements employ mechanical fasteners. Twenty and twenty aluminum alloy 6061-T6 plates, representing four different bolt patterns, were mechanically deformed. And variable materials such as A1 6061-T6, Al 2024-T3, Carbon/Epoxy, Glass/Epoxy Composite and Woven fiber composite, are used as patch materials. From this experiment, it has been shown that the strength of patch-repaired specimens is different with the patch materials.

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Robust inverse identification of piezoelectric and dielectric effective behaviors of a bonded patch to a composite plate

  • Benjeddou, Ayech;Hamdi, Mohsen;Ghanmi, Samir
    • Smart Structures and Systems
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    • v.12 no.5
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    • pp.523-545
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    • 2013
  • Piezoelectric and dielectric behaviors of a piezoceramic patch adhesively centered on a carbon composite plate are identified using a robust multi-objective optimization procedure. For this purpose, the patch piezoelectric stress coupling and blocked dielectric constants are automatically evaluated for a wide frequency range and for the different identifiable behaviors. Latters' symmetry conditions are coded in the design plans serving for response surface methodology-based sensitivity analysis and meta-modeling. The identified constants result from the measured and computed open-circuit frequencies deviations minimization by a genetic algorithm that uses meta-model estimated frequencies. Present investigations show that the bonded piezoceramic patch has effective three-dimensional (3D) orthotropic piezoelectric and dielectric behaviors. Besides, the sensitivity analysis indicates that four constants, from eight, dominate the 3D orthotropic behavior, and that the analyses can be reduced to the electromechanically coupled modes only; therefore, in this case, and if only the dominated parameters are optimized while the others keep their nominal values, the resulting piezoelectric and dielectric behaviors are found to be transverse-isotropic. These results can help designing piezoceramics smart composites for various applications like noise, vibration, shape, and health control.

Experimental and numerical study of effect of the fibers orientation of the different types of composite plates notched of U-shape repaired by composite patch

  • Berrahou Mohamed;Amari Khaoula;Belkaddour Leila;Serier Mohamed
    • Structural Engineering and Mechanics
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    • v.88 no.3
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    • pp.201-208
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    • 2023
  • In this work, the effect of the correction fibers direction on the efficiency of repairing damaged composite plates was highlighted. The composite plates studied in this work consist of eight layers of graphite/epoxy, while the patch used in this repair consists of four layers of the same type. The results obtained in this work, whether with regard to the experimental or analytical side, showed that the fibers orientation affects the repair efficiency, so the closer the angle of fibers inclination is to the tensile strength direction, the performance of the composite material is ideal. Hence, we conclude that the composite materials with longitudinal fibers (Parallel to tensile strength) is the most powerful and efficient material in performance.

Fatigue Crack Growth Behavior of the Thin-to-Thick Type Stiffened Panels with Bonded Patch (접착 패칭된 박-후판 결합형 보강판의 피로균열성장 거동)

  • Rhee, Hwan-Woo;Kim, Seung-Hyun
    • Journal of Ocean Engineering and Technology
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    • v.22 no.3
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    • pp.89-95
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    • 2008
  • Fatigue cracked components often needs to be repaired during service. Standard repair schemes involve strengthening the component by connecting reinforcing members by means of rivets or welding by reducing the crack-tip stress intensity factors. Recent technological advances in fiber reinforced composite materials and adhesive bonding have led to the development of efficient repair schemes. In this study, the influence of various shape parameters on fatigue crack growth in the CCT type uniform thickness plates and the thin-ta-thick type stiffened panels repaired with woven fabric type Kevlar-Epoxy composite patch are studied experimentally.

3-D fracture analysis of cracked aluminum plates repaired with single and double composite patches using XFEM

  • Jamal-Omidi, Majid;Falah, Mehdi;Taherifar, Davood
    • Structural Engineering and Mechanics
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    • v.50 no.4
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    • pp.525-539
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    • 2014
  • Bonded composite-patch repair has been widely used to restore or extend the service life of damaged structures due to its effectiveness as a mechanical repair technique. In this paper using extended finite element method (XFEM), three-dimensional crack models are developed to examine the fracture behavior of centrally cracked aluminum plates repaired with single and double sided composite patches. Stress intensity factor (SIF) at the crack tip is used as the fracture criterion. In this regard, the effects of the crack lengths, patch materials, orientation of plies, adhesive and patch thickness are examined to estimate the SIF of the repaired plate and the repair performance. The obtained results show that composite patches have significant effect on reduction of the SIF at the crack tip. It is also proved that using double symmetric repair, in comparison to single one, reduces considerably SIF at the crack tip. Hence, the residual strength can be improved significantly as well as fatigue life of the structure. Investigation of ply orientation effects shows SIF increase as the ply orientation is changed from $0^{\circ}$ (perpendicular to the advancing crack) to $90^{\circ}$ (parallel to the crack line). However, the effectiveness of the ply orientation depends on the loading direction and the crack direction.