• International Journal of Aeronautical and Space Sciences
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• v.13 no.2
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• pp.229-237
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• 2012

In this study, the failure mechanism of sandwich-to-laminate T-joints under pull-off loading was investigated by experiment and the finite element method. A total of 26 T-joint specimens were manufactured and tested in order to investigate the effects of both adhesive thickness (0.4, 2.0, and 4.0 mm) and environmental conditions on the failure of the joints. The results showed that failure occurred mainly as intralaminar failure in the first layer of the sandwich face, which was contacted to the paste adhesive. The failure load did not significantly change with increasing adhesive thickness in both RTD (Room Temperature and Dry) and ETW (Elevated Temperature and Wet) conditions. In the case of ETW conditions, however, the failure load increased slightly with an increase in adhesive thickness. The joints tested in ETW conditions had higher failure loads than those tested in RTD conditions. In addition to the experiment, a finite element analysis was also conducted to investigate the failure of the joint. The stress inside the first ply of the sandwich face was of interest because during the experiment, failure always occurred there. The analysis results showed good agreement with the trend of experimental results, except for the case of the smallest adhesive thickness. The highest stress was predicted in the regions where initial failure was observed in the experiment. The maximum stress was almost constant when the adhesive thickness was beyond 2 mm.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.5
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• pp.1543-1551
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• 1996

The static tensile load bearing capability of as adhesively-bonded tubular single lap jint that is calculated usign the linear mechanical properties of adhesive is usually far from the experimentally determined because the majority of the load transfer of the adhesively-bonded jointd is accomplished by the nonlinear behavior of the rubber-toughened eoxy adhesive. In this paper, both the nonlinear mechanical properties and the fabrication residual thermal stresses of adhesive were included in the calculation of the stresses of adhesively-bonded joints. The onlinear tensile properties of adhesive were approximated by an exponential form which was represented by the initial tensile modulus and ultimate tensile stength of adhesive. The stress distribution in the adhesive were calculated by applying the load obtained from the tensile tests. From the tensile tests and the stress analysis of adhesively-bonded hoints, the failure model for adhesively-bonded tubular single lap joints was proposed.

• International Journal of Korean Welding Society
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• v.4 no.1
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• pp.53-60
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• 2004

Adhesive-bonded joints are widely used in the industry. Recently, applications of adhesive bonding joints have been increased extensively in automobile and aircraft industry. The strength of adhesive joints is influenced by the surface roughness, adhesive shape, stress distribution, and etc. However, the magnitude of the influence has not yet been clarified because of the complexity of the phenomena. In this study, as the fundamental research of adhesive bonding joints, the effects of adhesive shape and loading speed on bonding strength properties and durability of aluminum to polycarbonate single-lap joints were studied. To evaluate the effect of adhesive shape, several modified shapes were used, and loading speeds were varied from 0.05 to 5mm/min. As a result, the load distribution showed a brittle fracture tendency. The trigonal edged single lap and bevelled lap joints showed the higher strength than the plain single lap, trigonal single lap, joggle lap and double lap joints in same adhesive area. The fractures of trigonal single lap and trigonal edged single lap joints that had the higher strength level were shown as the mixture type of the cohesive and interfacial-failure, mostly joggle lap joints that had the lower strength level were shown as the adhesive-failure.

• Journal of the Korean Society for Nondestructive Testing
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• v.32 no.2
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• pp.122-130
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• 2012

Adhesive bend and shear tests of micro-sized bonded component have been performed to clarify the relationship between effects of heat-treatment on the adhesive strength and the bonded specimen shape using Weibull analysis. Multiple micro-sized SU-8 columns with four different diameters were fabricated on a Si substrate under the same fabrication condition. Heat-treatment can improve both of the adhesive bend and shear strength. The improvement rate of the adhesive shear strength is much larger than that of the adhesive bend strength, because the residual stress, which must change by heat-treatment, should effect more strongly on the shear loading. In case of bend type test, the adhesive bend strength in the smaller diameters (50 and $75\;{\mu}m$) widely vary, because the critical size of the natural defect (micro-crack) should vary more widely in the smaller diameters. In contrast, in case of shear type test, the adhesive shear strengths in each diameter of the columns little vary. This suggests that the size of the natural defects may not strongly influence on the adhesive shear strength. All the result suggests that both of the adhesive bend and shear strengths should be complicatedly affected by heat-treatment and the bonded columnar diameter.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.3A
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• pp.555-563
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• 2006

Recently, many bridges become not only functionally obsolete of bridge deck due to inadequate width but also structurally deficient of substructure due to erosion. In these cases, widening is almost always more economical than complete replacement, and therefore there is a need to make available the results of research and field experience pertaining to the widening of bridge substructure. But, an experimental study for the guarantee of unification between existing and new substructure with adhesive anchor is so insufficient that the development of adhesive anchor system for the unification should be settled promptly. The purpose of the present study is to explore pull out and shear characteristics of adhesive anchor system. For this purpose, several series of concrete specimens have been tested. Major test variables were the bonded length, anchor diameter and anchor slope. The pull out strength, bond stress and shear strength of adhesive faces were measured for the specimens. The present study indicates that the pull out strength increased with more bonded length and more anchor diameter, and that the bond stress decreased with more bonded length and more anchor diameter. The pull out strength and the bond stress increases with more anchor slope and it is considered that the slope of $5^{\circ}$ was more efficient. From the shear tests, it is supposed that anchor diameters more than D19 was proper to the adhesive anchor. Finally, it is expected that both experimental data in these tests and further study including mock-up tests will contribute to the establishment of the unification between existing and new substructure with adhesive anchor.

• Advances in materials Research
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• v.5 no.1
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• pp.11-20
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• 2016

In bonded composite repair of aircraft structures, the damage of the adhesive can thus reduce significantly the efficiency and the durability of the bonded composite repair. The adhesive damage models using critical zone have proven their effectiveness due to simplicity and ap-plicability of the damage criteria in these models. The scope of this study is to analyze the effects of the patch thickness and the adhesive thickness on the damage damage in bonded composite repair of aircraft structures by using modified damage zone theory. The obtained results show that, when the thickness of adhesive increases the damage zone increases and the adhesive loses its rigidity, inversely when the patch is reduced the adhesive damage be-comes more significant.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.7
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• pp.171-176
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• 2003

In this study, stress analysis using Boundary Element Method (BEM) was carried to investigate stress distribution in the brazing joint between a Hardmetal and a HSS. The two models were proposed to analyze the stress singularity in the interfaces of the brazing joint. The material type, thickness of the filler metal and the length of the vertical brazing adhesive are considered in the BEM analysis. As results, the peak point of the stress is founded to be in the lower interface of the brazed joint. It should be noted that the maximum stress of the peak point is being affected by the thickness and length of the brazing joint.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2005.05a
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• pp.173-178
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• 2005

The tile construction methods for existing have been used materials within limit which adhesion by wet method in masonry wall and concrete structure. These existing adhesive tech can caused many problems in construction of large and reform tile, after that it can be happened loose scale, peel off, falling off tile by heat and vibration or impact. In according to, this study is to test tile for bond stability, adhesive property by impact, vibration. low property by heat and then, we have the results as below; (1) The tile adhesive stability can be effected as adhesive area between bond agent and tile, adhesive area can more wide and press enough to ensure property. (2) Existing adhesive strength and standard relative tile construction is limited to adjust performance tile on the concrete and masonry wall. In summary, It is necessary to establish standard of performance and test method to ensure tile adhesive salability in dry wall.

• 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.

• Journal of the Society of Naval Architects of Korea
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• v.58 no.2
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• pp.66-72
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• 2021

As the demand for natural gas that satisfies environmental regulations increases, the quantities of natural gas cargo that carrier can load is also increasing. Natural gas is transported in a liquefied state at -163 ℃ to increase loading efficiency. Among several LNG CCS types, MARK-III types are generally adopted in terms of loading efficiency. The secondary barrier adhesives of the MARK-III, nevertheless, is subjected to tensile stress due to thermal contraction and tension in the environment. In terms of these reasons, local analysis of the adhesive to evaluate the stress state must be carried out. According to previous studies, local analysis is unavailable since material properties for secondary barrier adhesives have not been reported. Thus, in this study, the cryogenic tensile test and coefficient of thermal expansion of epoxy and polyurethane (PU15, PU45), which are most widely used at cryogenic temperatures, were experimentally analyzed. At cryogenic temperature, the mechanical behavior of the polyurethane adhesive was better than epoxy of the adhesive. the joint of FSB and epoxy adhesive of the secondary barrier has the maximum coefficient of thermal expansion difference at 25 ℃ and minimum at -150 ℃, respectively.