• Title/Summary/Keyword: Bonded scarf joint

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EFFECTS OF INTERFACE CRACKS EMANATING FROM A CIRCULAR HOLE ON STRESS INTENSITY FACTORS IN BONDED DISSIMILAR MATERIALS

  • CHUNG N.-Y.;SONG C.-H
    • International Journal of Automotive Technology
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    • v.6 no.3
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    • pp.293-303
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    • 2005
  • Bonded dissimilar materials are being increasingly used in automobiles, aircraft, rolling stocks, electronic devices and engineering structures. Bonded dissimilar materials have several material advantages over homogeneous materials such as high strength, high reliability, light weight and vibration reduction. Due to their increased use it is necessary to understand how these materials behave under stress conditions. One important area is the analysis of the stress intensity factors for interface cracks emanating from circular holes in bonded dissimilar materials. In this study, the bonded scarf joint is selected for analysis using a model which has comprehensive mixed-mode components. The stress intensity factors were determined by using the boundary element method (BEM) on the interface cracks. Variations of scarf angles and crack lengths emanating from a centered circular hole and an edged semicircular hole in the Al/Epoxy bonded scarf joints of dissimilar materials are computed. From these results, the stress intensity factor calculations are verified. In addition, the relationship between scarf angle variation and the effect by crack length and holes are discussed.

Strength Evaluation of Bonded Dissimilar Materials by Using Stress Singularity Factor (응력특이성계수에 의한 이종 접합재료의 강도평가)

  • Jeong, Nam-Yong;O, Bong-Taek
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.20 no.7
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    • pp.2087-2096
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    • 1996
  • Recentrly advantages in composite and light weight material techniques have led to the increased use of bonded dissimilar materials such as ceramics/metal bonded joints, IC package, brazing, coating and soldering in the various industries. It is required to analyze the evaluation method of fracture strength and design methodology of bonded joints in dissimilar materials. Stress singularity according to changes of scarf angles for bonded scarf joints in dissimilar materials was investigated by the boundary element method and static experiments. In this paper, effect of the stress singularity factors at the interface edges of scarf joints on various dissmilar materials combinations were investigated by analysis of its stress and stress singularity index using 2-dimensional elastic program of boundary element method. And the variations of stress singularity index by changes for Young's modulus ratios of materials and scarf angles were investigated. Also, it is found that stress singularities at bonded interface edges are disappeared for certain combination of scarf angle in a pair of bonded dissimilar materials. As the results, it is proposed that the strength evaluation by using stress singularity factors, $\Gamma$, considering stress singularity at the interface edges of bonded dissimilar materials, is very useful.

Evaluation Method of Interface Strength in Bonded Dissimilar Materials of AU/Epxy (Al/ Epoxy 이종 접합체에 대한 계면강도의 평가방법)

  • Chung, Nam-Yong
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.26 no.11
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    • pp.2277-2286
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    • 2002
  • The application of bonded dissimilar materials to industries as automobiles, aircraft, rolling stocks, electronic devices and engineering structures is increasing gradually because these materials, compared to the homogeneous materials, have many advantages for material properties. In spite of such wide applications of bonded dissimilar materials, the evaluation method of quantitative strength considering the stress singularities for its bonded interface has not been established clearly. In this paper, the stress singularity for Bctors and the stress intensity factors were analyzed by boundary element method(BEM) for the scarf joints of Al/Epoxy with and without a crack, respectively. From static fracture experiments of the bonded scarf joints, a fracture criterion and a evaluation method of interface strength in bonded dissimilar materials were proposed and discussed.

Evaluation of Fracture Toughness on Interface Cracks in Bonded Components of Dissimilar Materials (이종 접합부재의 계면균열 파괴인성의 평가)

  • Chung, Nam-Yong;Lee, Myung-Dae;Park, Chul-Hee
    • Proceedings of the KSME Conference
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    • 2003.04a
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    • pp.346-351
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    • 2003
  • In this paper, an evaluation method of fracture toughness on interface cracks has been investigated under various mixed-mode conditions of the bonded scarf joints. Two types of the bonded scarf joints with an interface crack were prepared to analyze the stress intensity factors using boundary element method(BEM) and to perform the fracture toughness test. From the results of fracture toughness experiments and BEM analysis, an evaluation method of fracture toughness on interface cracks in the bonded components of dissimilar materials has been proposed and discussed.

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An Evaluation Method of fracture Toughness on Interface Cracks in Bonded Dissimilar Materials (이종 접합체의 계면균열에 대한 파괴인성의 평가방법)

  • 정남용
    • Transactions of the Korean Society of Automotive Engineers
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    • v.11 no.4
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    • pp.110-116
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    • 2003
  • In this paper, an evaluation method of fracture toughness on interface cracks has been investigated under various mixed-mode conditions of the bonded scarf joints. Two types of the bonded scarf joints with an interface crack were prepared to analyze the stress intensity factors using boundary element method(BEM) and to perform the fracture toughness test. From the results of fracture toughness experiments and BEM analysis, an evaluation method of fracture toughness on interface cracks in the bonded dissimilar materials has been proposed and discussed.

Effect of Micro-bolt Reinforcement for Composite Scarf Joint (복합재 스카프 조인트에서의 마이크로 볼트 보강에 대한 타당성 연구)

  • Lee, Gwang-Eun;Sung, Jung-Won;Kweon, Jin-Hwe
    • Composites Research
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    • v.32 no.1
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    • pp.37-44
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    • 2019
  • The reinforcement effect of micro-bolt for a bonded scarf joint was investigated. Three scarf ratios of 1/10, 1/20, and 1/30 were considered to examine the effect of scarf patch configuration on joint strength. To maintain the same density of micro-bolt, 16, 32, and 48 bolts were installed in the scarf joint specimens with scarf ratios of 1/10, 1/20, and 1/30, respectively. Tests were also carried out on the joints that are bonded with only adhesive and that are fastened with only micro-bolts to obtain reference values. The average failure loads of the adhesive joints with scarf ratios of 1/10, 1/20, and 1/30 were 29.7, 39.6, and 44.8 kN, respectively. In case of micro-bolt reinforcement, the failure loads at the same scarf ratios were 28.4, 37.2, and 40.1 kN, respectively, which corresponds to 96, 94, and 90% of the pure adhesive joint failure loads. In the case of using only micro-bolts, the failure loads were only 13-25% of the average failure loads of pure adhesive joints. Fatigue test was also conducted for the joints with scarf ratio of 1/10. The results show that the fatigue strength of hybrid joints using both adhesive and microbolts together slightly increased compared to the fatigue strength of adhesive joint, but the rate of increase was small to 2-3%. Through this study, it was confirmed that the reinforcement effect of micro-bolt is negligible in the scarf joints where shear stress is dominating the failure, unlike in the structure where peel stress is dominant.

Prediction Fracture Strength on Adhesively Bonded scarf Joints in Dissimilar Materials (이종재료의 경사접착이음에 대한 파괴강도의 예측)

  • 정남용
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.4 no.4
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    • pp.50-60
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    • 1995
  • Recently advantages joining dissimiliar materials and light weight material techniques have led to increasing use of structural adhesives in the various industries. Stress singulartiy occurs at the interface edges of adhesively bonded dissimilar materials. So it is required to analyze its stress singularity at the interface edges of adhesively bonded joints indissimilar materials. In this paper, the analysis method of stress singularity is studied in detail. Also, effects of the stress singularity at the interface edge of adhesively bonded scarf joints in combinations of dissimilar materials are investigated by using 2-dimensional elastic program of boundary element method. As the results, the strength evaluation method of adhesively bonded dissimilar materials using the stress singularity factor, $\Gamma$,is very useful. The fracture criterion, method of strength evaluation and prediction of fracture strength by the stress singularity factor on the adhesively bonded dissimilar materials are proposed.

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Longitudinal Bonding Strength Performance Evaluation of Larch Lumber (낙엽송 소경각재의 종접합 성능평가)

  • Lee, In-Hwan;Pack, Ju-hyun;Song, Da-bin;Hong, Soon-Il
    • Journal of the Korean Wood Science and Technology
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    • v.46 no.1
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    • pp.85-92
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    • 2018
  • In order to use glued built up timber beam as a structural member for post and beam construction, it must be possible to manufacture long-span lumber. In this study, the researchers conducted a performance evaluation for longitudinal bonding of lumber (cross-section $89{\times}120mm$) made from larch. The specimens were prepared in six different forms using the longitudinal bonding method. The bonding strength of these specimens was tested through tensile strength tests and bending strength tests. The tensile strength test result of the longitudinally bonded parts was better than that of the double lap specimens. And, the tensile strength value of the scarf specimen was better than that of the hooked scarf specimen. The tensile strength of the GFRP (Glass Fiber Reinforced Plastic) rod insertion bonding specimen was 3.6 MPa, which was the highest. As for the bending strength test result of the longitudinally bonded part, the average MOR (modulus of rupture) of the specimen where a GFRP rod was inserted and bonded measured 29 MPa, while the specimens of other bonded parts showed a MOR no more than 11 MPa. Toughness destruction was observed in specimens where a GFRP rod was insertion-bonded. The rest of the specimens showed brittle destruction. The average MOR strength of the Rod + Lap specimen was 30.5 MPa, which was the highest among all longitudinally bonded specimens. The bending strength of the Rod + Lap specimens showed an effective strength that was 66% of that of the control group which were not longitudinally bonded.

Fracture criterion of mixed mode in adhesively bonded joints of Al/Steel dissimilar materials (Al/Steel 이종재료의 접착이음에 대한 혼합모드의 파괴기준)

  • Jeong, Nam-Yong;Jang, Jin-Mo
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.21 no.8
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    • pp.1322-1331
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    • 1997
  • A method of strength evaluation applying fracture mechanics in the adhesively bonded joints of Al/Steel dissimilar materials was investigated in this paper. Various shapes of adhesively bonded Al/Steel scarf joints focussing on fracture criterion of mixed mode crack were prepared for the static tests. Also, stress intensity factors of the interface cracks in adhesively bonded joints of Al/Steel dissimilar materials were analyzed with 2-dimensional elastic program of boundary element method(BEM), and the experiment of fracture toughness were carried out under various mixed mode conditions. From the results, the fracture criterion and method of strength evaluation by the fracture toughness in adhesively bonded joints of Al/Steel dissimilar materials were proposed.

Prediction of Propagation Path for the Interface Crack in Bonded Dissimilar Materials (이종접합재의 계면균열에 대한 진전경로의 예측)

  • 정남용;송춘호
    • Transactions of the Korean Society of Automotive Engineers
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    • v.4 no.3
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    • pp.112-121
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    • 1996
  • Applications of bonded dissimilar materials such as metal/ceramics and resin/metal joints, are very increasing in various industry fields. It is required to find crack propagation direction and path applying to the fracture mechanics on the bonded joint of dissimilar meterials. In this paper, crack propagation direction and path were simulated numerically by using boundary element method. Crack propagation angle is able to easily determine based on the maximum stress concept. Fracture tests of Al/Epoxy dissimilar materials with an interface crack are carried out under various mixed mode conditions by using the specimens of bonded scarf joints. It is found that the experimental results are well coincide with the analysis results of boundary element method.