고분자 접착제와 금속 피착재의 접착강도에 미치는 피착재 두께의 영향

하윤근,심준형,백주환,김민균,조영래,Ha, Yungeun,Sim, Jun-Hyung,Baeg, Ju-Hwan,Kim, Min-Kyun,Cho, Young-Rae 한국마이크로전자및패키징학회 2020 마이크로전자 및 패키징학회지 Vol.27 No.4

고분자 재료인 접착제와 금속 피착재 사이의 정량적인 접착강도 측정은 중요하다. 고분자 재료인 접착제와 금속 피착재 사이의 접착강도 측정 시, 피착재의 종류와 두께 변화가 접착강도에 미치는 영향에 대해 연구하였다. 금속 피착재의 종류로는 알루미늄과 스텐리스강 2종류가 선택되었으며, 접착강도의 측정에는 돌리테스트와 전단시험이 사용되었다. 인장응력 방식의 돌리테스트로 고분자 접착제와 금속 피착재 사이의 접착강도 측정 시, 금속 피착재의 두께 변화는 접착강도의 크기에 거의 영향을 미치지 않았으나, 피착재의 종류에 따라 접착강도는 다르게 나타났다. 반면, 전단시험으로 고분자 접착제와 금속 피착재 사이의 접착강도 측정 시, 금속 피착재의 상대적 두께 변화는 접착강도의 크기에 영향을 주었다. 이유는 전단시험 시 접착부의 모서리 부분에서 발생하는 피착재의 휘어짐 현상은 접착부에 추가적인 인장응력을 발생시켜 접착강도를 낮추는데 기여하기 때문이다. 이 연구의 결과, 돌리테스트는 피착재의 두께가 변해도 접착강도의 변화가 거의 없기 때문에 고분자 접착제와 금속 피착재의 정량적인 접착강도 측정 시 널리 사용될 것으로 예상된다. It is important to measure the quantitative adhesive strength between an organic adhesive and a metal adherend. In measuring the adhesive strength between an organic adhesive and a metal adherend, the effect of the kind and thickness of the adherend on the adhesive strength was studied. Two kinds of metal adherends were selected, aluminum (Al1050) and stainless steel (STS304), and a dolly test and a lap shear test were used to measure the adhesive strength. When measuring the adhesive strength between the organic adhesive and the metal adherend by the tensile stress mode of dolly test, the change in the thickness of the metal adherend had little effect on the adhesive strength, however, the adhesive strength was different depending on the kind of the adherend. On the other hand, when measuring the adhesive strength between the organic adhesive and the metal adherend by the lap shear test, the change in the relative thickness of the metal adherend had an effect on the adhesive strength. The reason is that the bending phenomenon of the adherend occurring in the edge of bonding region during the lap shear test contributes to lowering the adhesive strength by generating additional tensile stress in the bonding region. From this work, it is concluded that the dolly test could be widely used when measuring the quantitative adhesive strength of organic adhesives and metal adherend because there is little change in adhesive strength even though the thickness of the adherend is changed.

접착제 접합 이음부 접합강도 평가에 대한 실험적 연구

강기엽,이제명,Kang, Ki-Yeob,Lee, Jae-Myung 대한용접접합학회 2012 대한용접·접합학회지 Vol.30 No.6

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.

단일겹치기이음시험을 이용한 합금화용융아연코팅강판의 코팅층 접합강도 평가

이정민(Jungmin Lee),이찬주(Chanjoo Lee),고대철(Daecheol Ko),이선봉(Seonbong Lee),김병민(Byungmin Kim) 대한기계학회 2009 大韓機械學會論文集A Vol.33 No.6

This paper was designed to estimate the adhesion strength of galvannealed coatings on steel sheets. The adhesion strength were evaluated using single lap - shear tests where the lap joint was bonded by structural adhesive. Tests were performed for overlap length of 5㎜, 10㎜ and 15 ㎜ and three directions (0, 45, 90) of steel sheets used as the adherend of the overlap joint. After the tests, FE simulations of the single lap - shear test were also carried out to observe the stress distribution in the interface between the adhesive and the coated sheet. The results showed that the joint failure loads obtained from the tensile tests of bonded single lap-joints were the same, regardless of overlap lengths and directions of steel sheets. Also, the failure of galvannealed coatings greatly depended on shear stress distribution in the interface and the value was about 30㎫.

Tensile shear strength of wood bonded with urea-formaldehyde with different amounts of microfibrillated cellulose

Heon Kwon, J.,Lee, S.H.,Ayrilmis, N.,Hyung Han, T. Butterworth-Heinemann Ltd. 2015 International journal of adhesion & adhesives Vol.60 No.-

Urea-formaldehyde (UF) adhesive mixtures with a 5% suspension of microfibrillated cellulose (MFC) at 0.5, 1, 3, and 5wt% loading levels based on the solid weight (62.4%) of the UF adhesive were prepared. Beech lamellas with dimensions of 5mmx20mmx150mm were prepared from beech lumbers using a planer saw. The UF adhesive (E0 class) was mixed with the MFC using a magnetic stirrer to achieve a proper distribution of the MFC in the UF adhesive. The tensile shear strength of single lap-joint specimens bonded with UF adhesive containing MFC was determined in accordance with EN 205 (2003). The specimens bonded with UF adhesive containing the MFC showed better tensile shear strengths as compared to the control. As compared to the control specimens, the tensile shear strength of the specimens increased by 5.7% as 3wt% of the MFC was incorporated into the UF adhesive. However, a further increment in the MFC content up to 5wt% decreased the tensile shear strength of the specimens (-14.3% of control specimen). The MFCs were well dispersed in the UF resin and were cross-linked to form a network to reinforce the bond line, improving bonding performance.

Effect of adhesive layer properties on the shear strength of single-lap structures of dissimilar materials based on the cohesive zone model

Jiwei Huang,Jie Zeng,Yufang Bai,Zhuming Cheng,Yong Wang,Qidi Zhao,Dakai Liang 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.1

An analysis method for improving the shear strength for the single-lap joints of dissimilar materials based on the cohesive zone model (CZM) is presented in this paper. The shear-lag model is established for the single-lap joint, and the stress distribution of joints is derived on the basis of this model, which is verified by simulation. The bilinear CZM is constructed to simulate the fracture process of joints, and the influence of lap length and adhesive layer thickness on the stress distribution of adhesive layers is comprehensively analyzed through simulation. Therefore, the effects of different properties of adhesive layers on the bonded structure strength are discussed with experiments. Results show that the reasonable lap length and thickness in this work are, respectively, 20-22 and 0.4-0.6 mm. The research results will serve as a guide for the parameter design, fracture prediction, and performance optimization of bonded joints.

차체 구조용 에폭시 접착제의 접합강도에 미치는 나노 기능성 블록공중합체 첨가의 영향

이혜림(Hye-rim Lee),이소정(So-jeong Lee),임창용(Chang-young Lim),서종덕(Jong-dock Seo),김목순(Mok-soon Kim),김준기(Jun-ki Kim) 대한용접·접합학회 2015 대한용접·접합학회지 Vol.33 No.4

The structural epoxy adhesive used in car body assembly needs the highest level of joint mechanical strength under lap shear, T-peel and impact peel conditions. In this study, the effect of nano functionalized block copolymer addition on the impact peel strength of epoxy adhesive was investigated. DSC analysis showed that the addition of nano functionalized block copolymer did not affect the curing reaction of epoxy adhesive. From single lap shear test, it was found out that the addition of nano functionalized block copolymer slightly decreased the cohesive strength of cured adhesive layer. The addition of nano functionalized block copolymer showed beneficial effect on T-peel strength by changing the adhesive failure mode to the mixed mode. However, the addition of nano functionalized block copolymer just decreased the room temperature impact peel strength. It was considered that the addition of nano functionalized block copolymer could have effect on disturbing the crack propagation only for the case of slow strain rate.

Steel/CFRP 이종소재의 표면거칠기에 따른 접합특성 분석에 관한 연구

최찬웅(Chan-Woong Choi),전병욱(Byung-Wook Jeon),강기원(Ki-Weon Kang),진지원(Ji-Won Jin) 대한기계학회 2021 大韓機械學會論文集A Vol.45 No.11

본 논문에서는 steel/CFRP 이종소재의 표면거칠기에 따른 접합강도를 평가하고 분석하였다. 먼저 접합강도 산출을 위해 ASTM D3163에 따라 단일 겹침 전단 시편을 제조하였으며, 접착제의 접착두께를 선정하기 위해 접착두께 변화에 따른 접합강도를 산출하여 최적의 접착두께 0.3 mm를 도출하였다. 다음으로 steel 및 CFRP 소재에 적합한 표면거칠기 선정을 위해 표면거칠기에 따른 접합시험을 수행하였으며, steel 시편의 표면거칠기(Ra)는 1.0~2.0이고, CFRP 시편의 표면거칠기(Ra)는 1.2~2.0으로 적용하였다. 해당 조건을 이용해 접착두께가 0.3 mm인 접합시편을 제작하고 접합강도를 측정함으로 steel 및 CFRP에 적합한 표면거칠기를 선정하였다. 최종적으로 steel/steel, CFRP/CFRP 및 steel/CFRP 접합시편의 표면거칠기에 따른 접합 강도를 분석함으로 steel/CFRP 이종소재에 적합한 표면거칠기를 도출하였다. The bond strength according to the surface roughness of a steel/carbon-fiber-reinforced polymer (CFRP) multimaterial was evaluated and analyzed. First, we prepared a single-lap shear specimen to calculate the bonding strength and analyzed the bonding strength according to the change in the bonding thickness of the adhesive to derive the bonding thickness of 0.3 mm. Next, a bonding test was performed according to the surface roughness of steel and CFRP; the surface roughness (Ra) of the steel specimen was 1.0~2.0 and that of the CFRP specimen was 1.2~2.0. The surface roughness suitable for steel and CFRP was selected by manufacturing a bond specimen with an adhesive thickness of 0.3 mm and measuring the bond strength. Finally, we analyzed the bond strength according to the surface roughness of steel/steel, CFRP/CFRP and steel/CFRP bond specimens and derived the surface roughness suitable for steel/CFRP multimaterial.

구조보강용 FRP 함침·접착수지의 역학적 특성 분석을 위한 시험방법 비교 연구

유영찬,최기선,김긍환 한국구조물진단유지관리공학회 2008 한국구조물진단유지관리공학회 논문집 Vol.12 No.2

FRP와 콘크리트의 접착강도를 평가하기 위해 현장에서 일반적으로 사용되는 Pull-off 실험방법은 FRP 복합체의 손상을 초래하며 더욱이 FRP의 최대 pull-off 강도가 콘크리트의 인장강도에 의해 제한 되는 단점을 지니고 있다. 이에 따라 구조보강용 접착제의 역학적 특성을 1차적으로 평가할 수 있는 간접적인 실험방법의 개발이 요구된다. 본 연구에서는 여러나라에서 각기 제안되고 있는 실험규격에 대한 비교실험을 통하여 구조보강용 접착제의 역학적 특성을 개략적으로 예측할 수 있는 표준화된 실험방법 및 평가기준을 제안하고자 하였다. 본 연구결과를 바탕으로 인장전단접착강도 시험의 접착제 두께, 압축/휨강도 시험체의 제원 등이 통일되어 표준시험체 제원을 도출할 수 있었다. Pull-off test is generally used to evaluate bond strength of FRP composite with concrete at job site. However, some damages on FRP composites can not be avoided during pull-off test and moreover test range of pull-off strength is limited by maximum tensile strength of concrete. Accordingly, it is required to set-up a test method that can evaluate mechanical properties of structural adhesive indirectly prior to pull-off test. In this study, the standard test methods for structural adhesive which can simply evaluate mechanical performance of adhesive were suggested through comparative experiments from each different standard in various countries. Particularly, gluing thickness of adhesive in tensile lap-shear tests, the section dimension of compression and bending test specimens become unified, and standard test specimen size is achieved by test results.

Effect of molecular weight of polyurethane toughening agent on adhesive strength and rheological characteristics of automotive structural adhesives

Kim, Daeyeon,Lee, Dong Geun,Kim, Jin Chul,Lim, Choong Sun,Kong, Nam Sik,Kim, Jin Hong,Jung, Hyun Wook,Noh, Seung Man,Park, Young Il Butterworth-Heinemann Ltd. 2017 International journal of adhesion & adhesives Vol.74 No.-

<P><B>Abstract</B></P> <P>Rheological and adhesive properties of automotive structural adhesives including polyurethane (PU) toughening agents have been investigated by adjusting the molar ratio of polytetrahydrofuran (polyTHF) and hexamethylene diisocyanate (HMDI) for the control of molecular weight of a PU prepolymer. Thixotropic behavior, crosslinking characteristics, and lap-shear and T-peel adhesion strengths for various adhesives were significantly affected by single or binary-mixed PUs with different molecular weights. Thixotropic hysteresis loop of shear viscosity along with shear rate of an adhesive became larger with increasing PU molecular weight, exhibiting favorable flowability, however, the adhesion strengths were not satisfactory for injection and coating applications. We found that both rheological and adhesive properties of adhesives could be interestingly tuned by combining PU components with different molecular weights.</P>

스틸과 알루미늄의 이종재 레이저 용접특성

김용(Yong Kim) 대한용접·접합학회 2017 대한용접·접합학회지 Vol.35 No.5

By reducing vehicle weight, a significant increase in fuel efficiency and consequently a reduction in CO₂ emissions can be achieved. Currently a high interest in the production of hybrid weld seams between steel and aluminum exists. So in this paper work has been focused on lap joints laser welding of dissimilar metallic materials by welding steel to aluminum. Materials used one of the car body steel (DP590) and aluminum alloy (Al5052) and both of the material thickness are 1.2mm. Steel sheet is positioned on the top of the aluminum sheet with overlap length of 25mm. Also, multiple laser welding have been achieved and distance of bead is changed to investigate the influence on tensile shear strength. As the results, there exist a certain condition of penetration (about 0.3 to 0.4mm) to show a maximum tensile strength. Also, the joint strength is increased by multiple laser welding. In this case bead distance is more important factor than bead path number.