• Title, Summary, Keyword: 접착강도시험

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A Study on Strength Evaluation of Adhesive Joints(1st Report, Stress Analysis and Fracture Strength of Adhesive Single-Lap Joint) (접착이음의 강도평가에 관한 연구 (제1보 겹치기 접착이음의 응력해석과 파괴강도))

  • 정남용
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.16 no.4
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    • pp.667-674
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    • 1992
  • Recently advantages in composite and light weight material technique have led to the increased use of structural adhesives in various industries. In spite of such wide application of the adhesive joints, the evaluation method of fracture strength and design methodology of them, have not been established. In this study finite element method, theoretical and experimental analyses were investigated according to changes of lap length and adhesive for adhesive single-lap joint. As the results, the strength evaluation of adhesive joint by conventional nominal stress, was pointed out inadequate strength evaluation and design method regardless stress singularity, stress distribution and crack propagation in its adhesive layer. Also, it was examined the problems to apply fracture mechanics by means of static and fatigue test.

The Bond Characteristics of Ultra Rapid Hardening Mortar for Repair using Magnesia-Phosphate Cement (마그네시아 인산염 시멘트를 이용한 초속경 보수 모르타르의 접착특성)

  • Lee, Sun-Ho;Kwon, Hee-Sung;Paik, Min-Su;Ahn, Moo-Young;Lee, Young-Do;Jung, Sang-Jin
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.609-612
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    • 2008
  • Ultra Super Early Strength Cement is a material that satisfies these requirements. early hydration heat however, is significant over regular concrete, thus discretion is advised for thermal cracks in accordance with heat generation when constructing a large-scale structures. In addition, the negative point that it is difficult to achieve required strength in a short period of time following rubbing process while retaining workability, the cement is being used conditionally for engineering material and Ultra Super Early Strength Cement for maintenance material for construction doesn't exist. Magnesia Phosphate Cement, which is currently under studies in overseas uses no extra admixture and has strong points of Ultra Super Early Strength as well as favorable construction-ability and adhesive stability to the prototype concrete. These factors stem recognition that it could be used as maintenance material for construction of diverse applicability. In order to provide necessary data to increase practicality of the magnesia phosphate cement for Ultra Super Early Strength Mortar, the study carried out simulate experiment on member of framework to review field applicability.

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A Study on the Fabrication of the Laminated Wood Composed of Poplar and Larch (포푸라와 일본잎갈나무의 집성재 제조에 관한 연구)

  • Jo, Jae-Myeong;Kang, Sun-Goo;Kim, Ki-Hyeon;Chung, Byeong-Jae
    • Journal of the Korean Wood Science and Technology
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    • v.2 no.2
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    • pp.25-31
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    • 1974
  • 1. Various gluing qualities applying Resorcinol Plyophen #6000 were studied on aiming the strength relationships of laminated woods resulted by single species [poplar (Populus deltoides), larch(Larix leptolepis)], mixed species of (poplar and larch), preservatives, treated poplar the scarf joint with mixed species of poplar and larch and the scarf joint treated with preservatives. 1. 1 On the block shear and on the DVL tension test, the mean wood failure ratio showed an excellent value i.e., above 65% and the tangential strength for larch was higher than that of radial, but it was reversed for poplar as shown in Tables 1 and 2. 1. 2 The lamina treated with Na-PCP reduced slightly the strength but the limited strength allowed for manufacturing laminated wood was not influenced by treating Na-PCP as shown in Tables 3 and 4. 1. 3 The safe scarf ratio in the plane scarf joint was above 1/12 for larch and 1/6 for poplar regard less of the chemical treatment or untreatment as shown in Tables. 5, 6, 7 and 8. 2. In the normal and boiled state, the gluing quality of the laminated wood composed of single[poplar (Populus deltoides), larch (Larix leptolepis)] and double species (poplar and larch) glued with Resorcinol Plyophen #6000 were measured as follow, and also represented the delamination of the same laminated wood. 2.1 The normal block shear strength of the straight and curved laminated wood (in life size) were more than three times of the standards adhesion strength. And, the value of the boiled stock was decreased to one half of the standard shear adhesion strength, but it was more than twice the standard strength for the boiled stock. Thus, it was recognized that the water resistance of the Resorcinol Plyophen #6000 was very high as shown in Tables 9 and 10. 2. 2 The delamination ratio of the straight and curved laminated woods in respect of their composition were decraesed, in turn, in the following order i. e., larch, mixed stock (larch+poplar) and poplar. The maximum value represented by the larch was 3.5% but it was below the limited value as shown in Table 11. 3. The various strengthes i.e., compressive, bending and adhesion obtainted by the straight laminaced wood which were constructed by five plies of single and double species of lamina i. e., larch (Larix leptolepis) and poplar (Populus euramericana), glued with urea resin were shown as follows: 3. 1 If desired a higher strength of architectural laminated wood composed of poplar (P) and larch (L), the combination of the laminas should be arranged as follows, L+P+L+P+L as shown in Table 12. 3.2 The strength of laminated wood composed of laminas which included pith and knots was conside rably decreased than that of clear lamina as shown Table 13. 3.3 The shear strength of the FPL block of the straight laminated wood constructed by the same species which were glued with urea adhesives was more than twice the limited adhesion strength, thus it makes possible to use it for interior constructional stock.

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Bonding Stress Analysis of Cable Fairings used in Small Guided Missiles and Strength Tests of Bonding Materials (유도무기 케이블 페어링의 강도 해석 및 접착재 강도 시험)

  • Goo, N.-S.;Yoo, K.-J.;Shin, Y.-S.;Lee, Y.-H.;Cheong, H.-Y.;Kim, B.-H.
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.33 no.6
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    • pp.76-82
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    • 2005
  • Cable fairings of guided missiles are generally used for protection of electric cables under aerodynamic heating and mechanical loading. The stress distributions between a cable fairing and missile main body along a cable fairing are necessary for its design. In this paper, a method for bonding stress and strength analysis of a cable fairing has been investigated and its computer program developed. Tensile and three-point bending tests of generally used bonding materials were also conducted to supply basic material properties for design of cable fairings.

Strength of Composit Single-lap Bonded Joints with Different Saltwater Moisture Contents (서로 다른 수분율을 갖도록 염수환경에 노출된 복합재 접착체결부의 강도)

  • Yang, Hyeon-Jeong;Jeong, Mun-Gyu;Kweon, Jin-Hwe;Choi, Jin-Ho
    • Composites Research
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    • v.24 no.4
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    • pp.48-54
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    • 2011
  • The effect of moisture contents by salt water on the strength of composite single-lap bonded joints is investigated. The specimens were manufactured in an autoclave by secondary bonding and immersed in the 3.5% salt water of $71^{\circ}C$ for different durations to get various moisture contents; 0, 0.2, 0.5, 1.0, and 2.0%(saturation). A total of 80 joint specimens were tested for 5 different moisture contents and 2 temperature environments. Test results show that while the joint strengths after the saturation of moisture decrease compared to those of dry ones, the strengths of the pre-saturated joint up to 1.0% of moisture content increase in both room and elevated temperature conditions. It is also shown that the strengths of joints tested in elevated temperature are slightly higher than the strength in room temperature by 2-5% until the moisture content reaches 1 %. In contrast, the high temperature strength of the saturated joint is about 5% lower than the room temperature strength.

Properties of Adhesion in Flexure and Tension of Polymer Cement Mortar Using SAE Emulsion with Blast-Furnace and Fly Ash as a Repair Material (보수재료로서 고로슬래그 미분말 및 플라이애쉬를 혼입한 SAE 에멀젼 기반 폴리머 시멘트 모르타르의 휨접착 및 인장접착 특성)

  • Jo, Young-Kug
    • Journal of the Korea Institute of Building Construction
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    • v.19 no.6
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    • pp.485-494
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    • 2019
  • This study is to evaluate the effect of admixtures such as blast-furnace slag and fly ash on adhesion in flexure and tension of polymer cement mortar(PCM) using SAE emulsion. The test specimens are prepared with five polymer-cement ratios and five admixture contents, and tested for flexural strength, adhesion in flexure, tensile strength and adhesion in tension. Based on the test results, no improvement of flexural strength and adhesion in flexure caused by admixtures in PCM can be indicated, but the tensile strength and adhesion in tension is improved due to mixing of the admixtures. In particular, the maximum of adhesion in tension of PCM with P/C 20% and BF content of 10% is 3.35MPa which is about 2.36 times higher than that of ordinary cement mortar, and 1.32 times that of PCM that does not contain any admixture. The average ratio of adhesion in tension to tensile strength of PCM was 48.7%. It is apparent that admixture contents of 5% or 10% could be proposed for improvement of tensile strength and adhesion in tension of PCM.

An Experimental Study on the Period of Cold Joint Occurrence Effecting Shear Bond Performances of UHSCC (콜드조인트 발생시간이 초고강도 섬유보강 시멘트 복합체의 전단 접착 성능에 미치는 영향에 관한 실험적 연구)

  • Kim, Min-Seong;Yang, Hyun-Min;Lee, Han-Seung;Cho, Keun-hee
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.20 no.1
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    • pp.25-32
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    • 2016
  • The purpose of this study is to evaluate the performance on the compressive bonding shear strength of ultra-high strength steel fiber reinforced cementitous composites(UHSCC). As a result of compressive bonding shear strength through Direct shear test, It was found that the specimen($150{\times}150{\times}150mm$) of NC(Normal concrete) + NC showed similar compressive bonding shear strength at whole experimental level. On the other hand, the specimen of UHSCC + UHSCC showed decrease of compressive bonding shear strength from after 30 minutes of the retarded placement than 0 minute. As a result of analyzing failure mode of bonding interface, It was found that the specimen of NC + NC showed mixed failure at whole experimental level. In case of the specimen of UHSCC + UHSCC, it showed interface failure from the specimen that are 30 minutes, 60 minutes and 90 minutes of delay of concrete placing. As a result of analyzing XRD test in terms of the placement interface on the specimen of NC and UHSCC, relatively much amount of $SiO_2$ was detected from the specimen of UHSCC than that of NC. It is judged that the most of main components of coating film shown in the specimen of UHSCC is $SiO_2$. In conclusion, it is judged that UHSCC which is made from after 30 minutes of delay of concrete placing is unable to be used as structural member because of deterioration of bonding performance. From later study, it is judged that the improvement of bonding performance from the part of cold joint occurrence is necessary through the interface preparation method.

A Study on the Improvement of Adhesion in Tension and Flexure of Polymer Cement Mortar Depending on Various Test Methods (시험방법에 따른 폴리머 시멘트 모르타르의 인장 및 휨접착강도 개선에 관한 연구)

  • Jo, Young-Kug
    • Journal of the Korea Institute of Building Construction
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    • v.19 no.1
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    • pp.47-57
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    • 2019
  • The purpose of this study is to evaluate the improvement effect of adhesion in tension and flexure of polymer cement mortars that have widely used as a repair-reinforcement material in construction field according to adding of polymer dispersions depending on different three types test methods. From the test results, the adhesion performance is improved with a raise in polymer-cement ratio irrespective of the type of polymer. The maximums of A type adhesion in tension, B type adhesion in tension and adhesion in flexure show 1.90 times, 2.17 times and 1.83 times, respectively that of plain cement mortar. The relative strength ratios, B type adhesion in tension and adhesion in flexure of polymer cement mortars to tensile and flexural strengths of plain mortar respectively are in ranges of 50.1% to 101.7% and 73.8% to 132.9% compared to 46.9% of plain mortar. It is apparent that polymer cement mortars with EVA and polymer cement ratios of 10% to 15% are recommended considering its adhesion performance and cost as a repair-reinforcement material in construction field.

Comparative Study on Test Methods for Mechanical Properties of Structural Adhesives Used in FRP Strengthening (구조보강용 FRP 함침·접착수지의 역학적 특성 분석을 위한 시험방법 비교 연구)

  • You, Young Chan;Choi, Ki Sun;Kim, Keung Hwan
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.12 no.2
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    • pp.103-112
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    • 2008
  • 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.