• International Journal of Aeronautical and Space Sciences
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• 제18권1호
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• pp.56-62
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• 2017

Because adhesively bonded joints are used in many structural systems, it is important to predict accurate adhesive strengths. Composite aircraft with many joints are easily exposed to low temperatures and high relative humidity. This paper presents a humidity aging effect on the adhesive strength of a composite single-lap joint (SLJ). The adhesive strength of the SLJ is predicted using a finite element analysis with a cohesive zone model (CZM) technique. The humidity aging effect is evaluated based on the adhesive strength and CZM parameters. A lap joint test is carried out on the composite SLJ specimens, which are exposed for four months of 100% R.H. at $25^{\circ}C$. The predicted strengths are in good agreement with experimental data, and the actual crack propagation is satisfactorily simulated using the local CZM technique.

• International Journal of Aerospace System Engineering
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• 제1권1호
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• pp.16-20
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• 2014

Recently, various kinds of study on light weight structure are performing in the world. The Al honeycomb sandwich structural type adopt for improvement of lightness and structural stability to major part structure of aircraft or spacecraft. Adhesion badness properties of adhesive and adhesion properties of fillet mainly studied about al honeycomb structure. But study for adhesive properties of sandwich construction with surface treatment of Aluminum alloy barely performed. In this study, adhesive film was used between Al and honeycomb core of honeycomb panel[1]. The study for adhesive properties of sandwich construction with surface treatment of AA 5052 skin was performed.

• 한국군사과학기술학회지
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• 제22권2호
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• pp.215-223
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• 2019

A high temperature adhesive development which is crosslinked in low temperature is necessary for aerospace application because of thermal expansion mismatches of various substrates. For this purpose, we have designed and fabricated several formulations with high temperature epoxy resins, crosslinkers and additives considering various working conditions and high service temperature. As a result, some formulations showed higher adhesive strengths than Hysol EA 9394/C2 which is widely used for aerospace applications. We also have studied and summarized the mechanical properties of the best development adhesive in both room and high temperatures.

• Composites Research
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• 제28권6호
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• pp.348-355
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• 2015

접착 조인트는 환경조건 및 작업자의 숙련도에 따라 접착강도가 크게 변화될 수 있으므로 이에 대한 비파괴 검사법은 매우 중요하다. 최근 접착제에 1-2 wt%의 CNT를 첨가하고 저항변화를 측정하여 접착 체결부의 내부 결함을 검출하는 전기저항법이 제시되었다. 전기저항법에서는 동일조건에서 접착조인트의 저항값이 일정하도록 하기 위하여 CNT의 균일한 분산이 매우 중요하며 이에 따라 결함 검출의 정확도가 좌우된다. 본 연구에서는 4가지 분산 방법으로 CNT를 접착제에 분산시켜 접착조인트을 제작하고 전기적 물리량을 측정하였다. 초음파를 이용한 CNT의 전처리 및 기화과정, 물리적 교반 방법등을 선정하여 효율적인 분산방법을 정립하고 분산성을 평가할 수 있는 척도를 제시하였으며 일반적인 분산 방법 대비 선정된 분산 방법을 적용했을 때 전기저항법의 결함검출능을 비교하였다.

• Advances in aircraft and spacecraft science
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• 제5권3호
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• pp.385-400
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• 2018

In this paper dynamic behavior (modal analysis and dynamic transient response) of a novel sandwich T-joint is numerically and experimentally investigated. An epoxy adhesive is selected for bonding purpose and making the step wise graded behavior of adhesive region. The effect of the step graded behavior of the adhesive zone on dynamic behavior of a sandwich T-joint is numerically studied. Finite element analysis (FEA) of the T-joints with carbon fiber reinforced polymer (CFRP) face-sheets is performed by ABAQUS 6.12-1 FEM code software. Modal analysis and dynamic half-sine transient response of the sandwich T-joint are presented in this paper. Two verification processes employed to verify the dynamic modeling of the manufactured sandwich panels and T-joint modeling. It has been shown that the step wise graded adhesive zone cases have changed the second natural frequency by about 5%. Also, it has been shown that the different arranges in the step wise graded adhesive zone significantly affect the maximum stresses due to transient dynamic loading by 1112% decrease in maximum peel stress and 691.9% decrease in maximum shear stress on the adhesive region.

• International Journal of Aerospace System Engineering
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• 제1권1호
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• pp.44-47
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• 2014

This study proposes a development for the nano silver adhesive, which is applicable to high efficiency LED(light-emitting diode) light. The important issue of LED light is heat exhaust from LED. Generally, the middle area of LED light is increased up to 380K. Therefore, the bottleneck between LED chip and heat sink are caused by high temperature. In this work, the adhesive material between LED Chip and heat sink was newly developed for improvement of bottleneck. The nano silver was adopted to solve heat problem of chip on board package for LED light. In order to evaluate the performance of the nano silver adhesive, the thermal analysis was performed. Moreover both adhesive performance and heat exhaust were verified through the prototype test. From the experimental test results, it is found that the developed nano silver adhesive has the high performance.

• International Journal of Automotive Technology
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• 제6권6호
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• pp.657-663
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• 2005

Recently, weight reduction of vehicles has been of great interest, and consequently the use of composite materials in the automotive industry is increasing every year. Composite sandwich panels which consist of two skins and core materials are replacing steels in automotive floor and door. The substitution of one material for another is accompanied by change of joining method, so that adhesive bonding has been popularly used for joining method of composite materials. In the case of adhesive bonding of composite materials, there could be loss in the joint strength by delamination of two faceplates or cracking on faceplate. Thus, it is necessary to prevent loss in the joint strength by designing the joint geometry. In the present paper, adhesive bonding of aluminum sandwich sheet was tried. For understanding joint behavior, studies on stresses in the single lap joint were reviewed and failure modes of composite material were analyzed. Strength tests on the single lap joint consisting of aluminum sandwich sheet and steel were performed and variation of the joint strength with the joint configuration was shown. Based on these results, design guide of adhesive bonding in aluminum sandwich sheet was suggested.

• 한국기계가공학회지
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• 제20권11호
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• pp.115-120
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• 2021

In this study, cigarettes, which are an essential element in the production of tobacco, are generally not cylindrical. The main materials used for cigarettes are generally hemp and pulp. For the production of cylindrical cigarettes, the cigarettes or cylinders are mounted via gluing. This adhesive is a vinyl acetate emulsion, a high-temperature melt adhesive, and is adhered in a cylindrical shape immediately after being linearly applied to the inner surface of the paper roll or a local part. These adhesives are greatly affected by the atmospheric temperature of the manufacturing space in summer and winter. In the summer, even if the adhesive is temporarily adhered, the coagulation time of the adhesive is long, and problems such as deterioration of the adhesive state occur. in the winter, there is a problem that the temperature of the manufacturing space is low and the adhesive force of the adhesive is poor, resulting in defective adhesive products. In order to solve these problems, another heat transfer device is utilized to cure the remaining adhesive to ensure higher adhesiveness.

• Composites Research
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• 제31권4호
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• pp.151-155
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• 2018

기계적 조인트와 접착 조인트는 구조물의 일반적인 접합 방법이다. 접착 조인트는 기계적 체결법에 비해 넓은 면적에 하중이 분포되고 우수한 피로 특성을 가진다. 이러한 특성에도 불구하고, 접착 조인트는 환경조건이나 작업자의 숙련도에 대한 접착 건전성이 크게 달라진다. 따라서 접착 조인트의 건전성을 평가 할 수 있는 기술이 필요하다. CNT를 접착제에 분산시켜 접착조인트의 전기적 특성을 측정하는 전기저항법은 결함을 검출하는 매우 유망한 기술이다. 본 논문에서는 초음파 분쇄기와 3-roll-mill을 이용하여 접착제에 CNT를 균일하게 분산시켰으며, 알루미늄-알루미늄 단일 접착 조인트를 제작하여 탄소나노튜브(CNT) 함량에 따른 정적 강도의 변화를 평가하고, 전기저항법을 이용하여 결함탐지능을 평가하였다.

• Composites Research
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• 제33권5호
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• pp.275-281
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• 2020

본 논문에서는 항공기 팬 블레이드에 적용되는 복합재와 금속 간의 접합 구조물에 대한 온도, 습도에 따른 접착제의 물성 변화에 관해 연구하였다. 항공기 운용 시 노출되는 환경 조건을 고려하여 상온 건조(Room Temperature Dry, RTD), 고온 흡습(Evaluated Temperature Wet, ETW), 저온 건조(Cold Temperature Dry, CTD) 세가지 환경에서 강도 시험을 수행하였다. 접착전단강도 시험은 ASTM D3528을 기준으로 수행하였고, 파손 영역에 대한 마이크로 구조 특성을 SEM이미지를 통해 분석하였다. 연구 결과에 따르면 RTD 환경에서의 전단강도 대비하여 ETW 환경에서 72.8% 저하되었으며, CTD 환경에서는 56.5% 증가되었다. 이는 고온 및 수분 흡습이 접착제의 기계적 특성에 큰 영향을 미치는 것을 확인했고, 저온 환경에서는 모재와 접착제 모두 취성의 증가로 인해 접착 전단 강도가 향상된 것으로 분석되었다.