• 제목/요약/키워드: Mechanical tests

검색결과 4,909건 처리시간 0.028초

축방향하중에 대한 튜브형 단면겹치기 접착조인트의 전적 파괴모델에 관한 연구 (Failure Model for the Adhesively Bonded Tubular Single Lap Joints Under Static Tensile Loads)

  • 김영구;이수정;이대길
    • 대한기계학회논문집A
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    • 제20권5호
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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.

Geophysical and mechanical investigation of different environmental effects on a red-bed soft rock dam foundation

  • Liming Zhou;Yujie Li;Fagang Wang;Yang Liu
    • Geomechanics and Engineering
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    • 제34권2호
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    • pp.139-154
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    • 2023
  • Red-bed soft rock is a common stratum and it is necessary to evaluate the mechanical properties and bearing capacity of red-bed soft rock mass affected by different environmental effects. This paper presents a complete procedure for evaluating the bearing capacity of red-bed soft rock by means of geophysical exploration and in-situ rock mechanics tests. Firstly, the thickness of surface loosened rock mass of red-bed soft rock was determined using geophysical prospecting method. Then, three environmental effects, including natural weathering effect, dry-wet cycling effect and concrete sealing effect, were considered. After each effect lasted for three months, in-situ rock mass mechanical tests were conducted. The test results show that the mechanical properties of rock mass considering the sealing effect of concrete were maintained. After considering the natural weathering effect, the mechanical parameters decrease to a certain extent. After considering the effect of dry-wet cycling, the decreases of mechanical parameters are the most significant. The test results confirm that the red-bed soft rock dam foundation rock mass will be significantly affected by various environmental effects. Therefore, combined with the mechanical test results, some useful implementations are proposed for the construction of a red-bed soft rock dam foundation.

베어링강의 기가사이클 피로 특성에 관한 연구 (Fatigue Characteristic of Bearing Steel(STB2) in Gigacycle)

  • 김상천;서창민;황병원;이태성
    • 한국해양공학회:학술대회논문집
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    • 한국해양공학회 2004년도 학술대회지
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    • pp.370-375
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    • 2004
  • Fatigue tests were carried out to find the fatigue characteristics in the super-long life range by using a cantilever type rotational bending fatigue test machine. Three kinds of specimen in bearing steels with the quenched and tempered in air (A and B, B: shot peened after heal treatment) and under vacuum conditions(C:non-shot peened)were tested in this study. S-N curves obtained from fatigue tests of C specimen tend to come dawn again in the super-long life range due to fish-eye type cracking, while most of A and B specimens fractured by surface defects such as scratches and slip lines. This duplex S-N behavior for the high strength steels have to be reviewed by the change of fracture modes.

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티타늄합금(Ti-6Al-4V)의 0.3Tm에서 크리프 특성 (Creep Characteristics of Titanium Alloy(Ti-6Al-4V) at 0.3Tm)

  • 윤종호;황경충;우현구
    • 한국자동차공학회논문집
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    • 제13권3호
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    • pp.117-122
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    • 2005
  • Titanium alloy has widely been used as material for glasses frame parts because it has high specific strength. It is also light and harmless to human body. However, we have little design data about the mechanical properties such as the creep behaviors of the alloy. Therefore, in this study, creep tests under four constant stress conditions have been conducted with four different temperature conditions. A series of creep tests had been performed to get the basic design data and life prediction of titanium products and we have gotten the following results. First, the stress exponents decrease as the test temperatures increased. Secondly, the creep activation energy gradually decrease as the stresses became bigger. Thirdly, the constant of Larson-Miller parameter on this alloy was estimated as about 2.5. Finally, the fractographs at the creep rupture showed the ductile fracture due to the intergranullar rupture and some dimples.

6000계열 알루미늄 합금의 극저온 기계적 거동 연구 (Study on Cryogenic Mechanical Behavior of 6000 Series Aluminum Alloys)

  • 박두환;김정현;최성웅;이제명
    • 한국해양공학회지
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    • 제29권1호
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    • pp.85-93
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    • 2015
  • In this study, tensile tests were performed on aluminum alloys (AA6061 and AA6082) to investigate their mechanical behaviors at cryogenic temperatures. The temperature was varied from 110 K up to 293 K, and quasi-static strain rates of 10−4 s−1 −10−2 s−1 were taken into account for the tests. The experimental results were analyzed to find the dependence on the temperature, strain rate, and fractured surfaces. As a result, it was found that the strength and elongation of the aluminum alloys were improved when the temperature was decreased. In addition, it was confirmed that the mechanical behaviors of the aluminum alloys were not dependant on the strain rate. Under a tensile load, two types of fractures were seen in the aluminum alloys: cup-cone (AA6061) and shear (AA6082).

Development of Roll-to- Flat Thermal Imprinting Equipment and Experimental Study of Large Area Pattern Replication on Polymer Substrate

  • 이문구;란 슈하이;이수훈;이혜진;;성연욱
    • 한국생산제조학회지
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    • 제18권3호
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    • pp.307-314
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    • 2009
  • Large area micro pattern replication has promising application potential in many areas. Rolling imprint process has been demonstrated as one of the most competitive processes for such micro pattern replication, because it has advantages in low cost, high throughput and high efficiency. In this paper, we developed a prototype of roll-to-flat(R2F) thermal imprint system for large area micro pattern replication process, which is one of the key processes in the fabrication of flexible displays. Experimental tests were conducted to evaluate the feasibility of system and the parameters' effect on the process, such as flat mold temperature, loading pressure and rolling speed. 100mm $\times$ 100mm stainless steel flat mold and commercially available polycarbonate sheets were used for the tests. The experimental results showed that the developed R2F system is suitable for fabrication of various micro devices with micro pattern over large area.

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Experimental Study on Neck Injury in Low Speed Frontal and Rear-End Collisions

  • Kim, Gyu-Hyun;Lee, Ouk-Sub;Hwang, Si-Won
    • Journal of Mechanical Science and Technology
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    • 제14권11호
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    • pp.1232-1243
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    • 2000
  • Motor vehicle accidents in rear impacts cause more than fifty percents of drivers to suffer from neck injuries. It is known that most neck injuries are associated with rear-end collisions at a speed lower than 32 km/h and between the Abbreviated Injury Scale (AIS) 1 and AIS 2. Two different types of low speed crash tests such as the frontal barrier and rear moving barrier crashes have been conducted by following the procedure of the Research Committee for Automobile Repairs (RCAR). The injury for the neck and the Head Injury Criteria (HIC) were measured by using the sensors mounted on dummies. We reviewed neck injures and the relationship between the neck and head injuries, and examined the deceleration of the body. Using the experimental test data at the neck, we investigated an improved neck injury criterion Nij. Also, the effects of the position of a head restraint on reducing the frequency and severity of the neck injury in rear-end collisions were investigated.

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멤브레인 LNG 저장탱크용 STS304L의 인장 및 피로강도 (Tensile and Fatigue Strengths of STS304L for LNG Membrane Storage Tank)

  • 나성현;김영균;김재훈
    • 한국안전학회지
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    • 제31권4호
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    • pp.9-14
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    • 2016
  • STS304L of membrane structure has been used for a LNG storage tank and has exposed long time under the cryogenic temperature. The purposes of this study are to evaluate the mechanical properties of base and used materials for STS304L of membrane. The tensile and high cycle fatigue tests were investigated for STS304L of membrane used over 20 years at room temperature and $-162^{\circ}C$. In addition, the test of base STS304L was performed in order to compare with used material properties. The chemical composition and phase change were investigated from EDS and XRD. From results of tensile test, yield and ultimate tensile strengths of used STS304L are smaller than those of base STS304L. S-N curves were obtained from fatigue tests at both temperatures. Also, P-S-N curves were presented with statistical method recommend by JSME-S002. Fractography was conducted for analysis of fracture mechanisms.

냉간압연강판 접용접재의 너깃간의 거리에 따른 피로거동 (A Fatigue Behavior for Spot Welded Steel Plate Carbon C by the Variation of the Interval Between Two Spots)

  • 송삼홍;양윤진;전재욱
    • 대한기계학회논문집A
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    • 제24권11호
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    • pp.2845-2852
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    • 2000
  • When welding a car frame with one spot welding there are same limitations because many parts of it cannot be simplified by one spot welding alone. It is presented two spot welding model for the description of the spot welding which is usually used in a car frame structure. This study primarily covers fatigue behavior taking spot welded SPCC(Steel plate carbon C) with different ungget intervals as a tension shear specimen. It was prepared that intervals between two nuggets are varied as 9mm, 14mm, and 20mm respectively. The tensile tests and fatigue tests were executed to know the mechanical properties under static and fatigue load condition. In addition, the relationship between fatigue life and nugget intervals was illustrated by finite element method.

Influence of laminated orientation on the mechanical and thermal characteristics of carbon-fiber reinforced plastics

  • Shin, Hee-Jae;Kwac, Lee-Ku;Lee, Min-Sang;Kim, Hong-Gun
    • Carbon letters
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    • 제16권4호
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    • pp.241-246
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    • 2015
  • Rapid industrial development in recent times has increased the demand for light-weight materials with high strength and structural integrity. In this context, carbon fiber-reinforced plastic (CFRP) composite materials are being extensively used. However, laminated CFRPs develop faults during impact because CFRPs are composed of mixed carbon fiber and epoxy. Moreover, their fracturing behavior is very complicated and difficult to interpret. In this paper, the effect of the direction of lamination in CFRP on the absorbed impact energy and impact strength were evaluated, including symmetric ply (0°/0°, −15°/+15°, −30°/+30°, −45°/+45°, and −90°/+90°) and asymmetric ply (0°/15°, 0°/30°, 0°/45°, and 0°/90°), through drop-weight impact tests. Further, the thermal properties of the specimens were measured using an infrared camera. Correlations between the absorbed impact energy, impact strength, and thermal properties as determined by the drop-weight impact tests were analyzed. These analyses revealed that the absorbed impact energy of the specimens with asymmetric laminated angles was greater than that of the specimens with symmetric laminated angles. In addition, the asymmetry ply absorbed more impact energy than the symmetric ply. Finally, the absorbed impact energy was inversely proportional to the thermal characteristics of the specimens.