• Title/Summary/Keyword: Adhesive Joints

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Effect of Spew fillet on Failure Strength Evaluation in Adhesive Bonded Joints involving Natural Fiber Reinforced Composites (접착제 접합된 자연섬유강화 복합재료의 파괴강도 특성에 미치는 접착제 필릿의 영향)

  • Kim, Yeon-Jik;Yun, Ho-Cheol;Im, Jae-Gyu
    • Proceedings of the KWS Conference
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    • 2005.06a
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    • pp.262-264
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    • 2005
  • This paper is concerned with a fracture strength study of composite adhesive lap joints. The tests were carried out on specimen joints manufactured hybrid stacked joints such as the polyester and bamboo natural fiber layer. The main objective of the work was to test the fracture strength using hybrid fiber composites with a polyester and bamboo natural fiber layer adjacent to the spew fillet of adhesive bonded joints and hybrid stacked joints. The results are presented using tensile-shear strength graph and finite element analysis. The failure mechanisms are discussed in order to explain that spew fillet at the end of the overlap reduces greatly the adhesive shear and effects the tensile-shear strength in hybrid stacked joints.

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Thermal Ratchetting of the Conductive Adhesives Joints Subjected to the Thermal Cycles (전도성 접착제의 열경화 응력에 대한 해석)

  • 박주혁;서승호
    • Proceedings of the International Microelectronics And Packaging Society Conference
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    • 2002.05a
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    • pp.208-213
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    • 2002
  • When a thermoset conductive adhesive joints are subjected to the thermal cycles, the thermal stresses are developed around the joints. Most of in-plane, hi-axial components of these residual stresses induces large tensile peel stresses and weakens adhesive joints. Also these stresses vary with thermal cycles, and result in thermal fatigue loading and debonding propagation. In this study, the thermal ratchetting effect in conductive adhesive joints are evaluated by the finite element analysis with the viscoelastic material model. In order to Investigate the relationship between thermal ratchetting and glass transition temperature, the mathematical material model has been developed experimentally by dynamic mechanical analysis. These material models are implemented to the finite element analysis with thermal loading cycles. And the stress profiles around the conductive adhesive joints are calculated. It has been observed that the thermal ratchetting occurs when the maximum temperature of thermal cycles is above the glass transition temperature. The peel and shear stress components increase as the thermal loading time increases. This will contributes to thermal fatigue fracture of the joints.

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Effects of the curing pressure on the torsional fatigue characteristics of adhesively bonded joints (경화 압력이 접착 조인트의 비틀림 피로 특성에 미치는 영향)

  • Hwang, Hui-Yun;Kim, Byung-Jung;Lee, Dae-Gil
    • Proceedings of the KSME Conference
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    • 2004.11a
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    • pp.196-201
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    • 2004
  • Adhesive joints have been widely used for fastening thin adherends because they can distribute the load over a larger area than mechanical joints, require no hole, add very little weight to the structure and have superior fatigue resistance. However, the fatigue characteristics of adhesive joints are much affected by applied pressure during curing operation because actual curing temperature is changed by applied pressure and the adhesion characteristics of adhesives are very sensitive to manufacturing conditions. In this study, cure monitoring and torsional fatigue tests of adhesive joints with an epoxy adhesive were performed in order to investigate the effects of the applied pressure during curing operation. From the experiments, it was found that the actual curing temperature increased as the applied pressure increased, which increased residual thermal stress in the adhesive layer. Therefore, the fatigue life decreased as the applied pressure increased because the mean stress during fatigue tests increased due to the residual thermal stress.

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On-line Cure Monitoring of Adhesive Joints by Dielectrometry (유전기법을 이용한 접착 조인트의 실시간 경화 모니터링)

  • 권재욱;진우석;이대길
    • Composites Research
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    • v.16 no.4
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    • pp.51-58
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    • 2003
  • Since the reliability of adhesively bonded joints is much dependent on the curing status of thermosetting adhesive, the on-line cure monitoring during the cure of adhesively joints could improve the quality of adhesively bonded joints. In this work, the dielectric method which measures the dissipation factor of the adhesive during the cure of joints and converts it into the degree of cure of the adhesive was devised. The relation between the dissipation factor and the degree of cure of adhesive was investigated, which could eliminate the temperature effect on the dissipation factor that is a strong function of the degree of cure and temperature of adhesive. From the investigation, it was found that the dissipation factor showed a trend similar to the cure rate of the adhesive.

Effect of Spew Fillet on Failure Strength Properties of Natural Fiber Reinforced Composites Including Adhesive Bonded Joints (접착제 접합된 자연섬유강화 복합재료의 파괴강도 특성에 미치는 접착제 필릿의 영향)

  • Yoon Ho-Chel;Choi Jun-Yong;Kim Yong-Jig;Lim Jae-Kyoo
    • Journal of Welding and Joining
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    • v.23 no.6
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    • pp.67-71
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    • 2005
  • This paper is concerned with a study on fracture strength of composites in an adhesive single lap joint. The tests were carried out on joint specimens made with hybrid stacked composites consisting of the polyester and bamboo natural fiber layer. The main objective of this work was to evaluate the fracture properties adjacent to adhesive bonded joint of natural fiber reinforced composite specimens. From the results, natural fiber reinforced composites have lower tensile strength than the original polyester. But tensile-shear strength of natural fiber reinforced composites with bamboo layer far from adhesive bond is as high as that of the original polyester adhesive bonded joints. Spew filet at the end of the overlap reduced the stress concentration at the bonded area. Spew fillet and position of bamboo natural fiber layer have a peat effect on the tensile-shear strength of natural fiber reinforced composites including adhesive bonded joints.

Nonlinear Analysis of Adhesive Tubular Joints with Composite Adherends subject to Torsion (비틀림 하중을 받는 복합재료 튜브형 접합부의 비선형 해석)

  • Oh Je-Hoon
    • Composites Research
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    • v.19 no.3
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    • pp.29-36
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    • 2006
  • Since composite materials have anisotropic properties that depend on their stacking angle and sequence, the analysis of joints with isotropic adherends is limited in describing the behavior of the adhesive Joint with composite adherends. In this study, the nonlinear solution for adhesive joints with composite adherends was derived by incorporating the nonlinear behavior of the adhesive into the analysis. The behavior of the laminated composite tube was first analyzed, and the stress distributions of the composite tubular adhesive joint were calculated by including the nonlinear properties of the adhesive. The effect of the stacking sequence of composite adherends and bonding length on torque capacities of joints was examined, and results of the nonlinear analysis were also compared with those of the linear analysis.

Effect of Adhesive Shape on the Strength of Aluminum/Polycarbonate Joint (접착부 형상이 알루미늄/폴리카보네이트 접합재의 강도에 미치는 영향)

  • Seo, Do-Won;Kim, Hyo-Jin;Choi, Jun-Yong;Hoa, Vu cong;Lim, Jae-Kyoo
    • Proceedings of the KSME Conference
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    • 2003.11a
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    • pp.1039-1044
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    • 2003
  • Adhesive-bonded joints are widely used in the industry. Recently aircraft applications of adhesive bonding joints have been increased extensively in automobile and air industry. Because adhesives which are available for structural applications have been developed a lot and understanding of adhesive bonding has been improved so much. In this study, as the fundamental research of design of adhesive bonding joints, this study considers specimen shape are affect strength and durability of Al/Polymer lap joints. In this research, cross head speed difference were concerned to evaluate their effects on the adhesive strength. Cross head speed makes a change 0.05mm/min, 0.5mm/min, 5mm/min. The result is load-displacement diagram showed brittleness fracture tendency. Fracture tendency that is shown enough on stress distribution of trigonal single lap joint and trigonal edged single lap joint occur the inside of adhesive.

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The Evaluation of Tensile-shear Strength on the Al-Alloy Single-lap Adhesive Joints (AI합금 단순겹치기 접착이음의 인장-전단강도 평가)

  • Oh, S. K.;Yu, Y. C.;Jeong, E. S.;Yi, W.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1997.04a
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    • pp.567-571
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    • 1997
  • Recently, automobile industry has led to increasing use of aluminum alloy for weight reduction. Automobile made of aluminum alloy can be given lighter, stronger and a harder surface by anodizing than one made of steel-alloy. In this paper, we investigate the influence of lap length, adherend thickness and adhesive thickness on adhesive strength of single-lap adhesive joints by conducting tensile-shear tests. Single-lap adhesive joints of aluminum was calculated using joint factor by using adhesive length, adherend thickness of specimen.

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Failure Load Prediction of the Composite Adhesive Joint Using the Damage Zone Ratio (파손영역비를 이용한 복합재 접착 체결부의 파손강도 예측)

  • Lee, Young-Hwan;Ban, Chang-Su;Choi, Jin-Ho;Kweon, Jin-Hwe
    • Composites Research
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    • v.21 no.4
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    • pp.22-28
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    • 2008
  • The composite joint has become an important research area because the structural efficiency of a structure with a joint is determined by its joints rather than by its basic structure since the joints are often the weakest areas in composite structures. In this paper, the strengths of adhesive joints consisting of metal and composites were predicted and tested by the maximum strain theory and damage zone theory. Nonlinear finite element analyses of adhesive Joints considering the material nonlinearity of the adhesive layer were performed. From the tests and analyses, the strengths of the adhesive joints could be predicted to within 22.2% using the damage zone ratio.

Experimental Study on Evaluation of Bonding Strength of Adhesively Bonded Joints by Adhesive (접착제 접합 이음부 접합강도 평가에 대한 실험적 연구)

  • Kang, Ki-Yeob;Lee, Jae-Myung
    • Journal of Welding and Joining
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    • v.30 no.6
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    • pp.62-67
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    • 2012
  • In this study, the bonding strengths of adhesively bonded joints are experimentally investigated. A series of lap-shear tests are conducted using single lap type adhesive joints. In order to analyse the joint fabrication factors that affected the bonding strength, the parametric tests are conducted with various thickness of adhesive, surface roughness and fillet of adhesive. In addition, for the comparative study with the welded joint, lap-shear tests using specimens with 2 welded sides and 4 welded sides are also carried out. The quantitative results of the strength analysis are summarized, and some proposals are made on setting up testing standards for adhesively bonded joints.