• Title, Summary, Keyword: 인장시험

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Comparison of Tensile Strengths in Granite Using Brazilian Tests and Hollow Cylinder Tests for Hydraulic Fracturing Test Interpretation (수압파쇄시험 해석을 위한 중공원통 인장시험과 압열인장시험 화강암 인장강도 비교)

  • Jo, Yeonguk;Chang, Chandong;Lee, Tae Jong;Kim, Kwang-Yeom
    • Tunnel and Underground Space
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    • v.23 no.5
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    • pp.362-371
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    • 2013
  • We conducted hollow cylinder tensile strength tests and Brazilian tests in Seokmo granite to measure tensile strength necessary for estimating the magnitude of the maximum horizontal principal stress in hydraulic fracturing stress measurements. Two different pressurization rates were used in hollow cylinder tests. Tensile strengths were determined to be higher at higher pressurization rate, which suggests that tensile strength should be measurement at the same rate used in actual in situ hydraulic fracturing tests. Considering the effect of pressurization rate and specimen size on tensile strength, the hollow cylinder tests and Brazilian tests yield similar results each other. This demonstrates that Brazilian tests can be utilized to produce representative tensile strengths for interpretation of hydraulic fracturing test results.

Study on the Direct Tensile Test for Cemented Soils Using a Built-In Cylinder (내장형 실린더를 이용한 시멘트 고결토의 인장시험 방법에 관한 연구)

  • Park, Sung-Sik;Lee, Jun-Woo
    • Journal of The Korean Society of Civil Engineers
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    • v.34 no.5
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    • pp.1505-1516
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    • 2014
  • In this study, a cylinder embedded within cemented soils was used to cause directly tensile failure of cemented soils. An existing dumbbell type direct tensile test and a split tensile test that is most general indirect tensile test were also carried out to verify the developed built-in cylinder tensile test. Testing specimens with two different sand/cement ratios (1:1 and 3:1) and two curing periods (7 and 28 days) were prepared and tested. Total 10 specimens were prepared for each case and their average value was evaluated. Unconfined compression tests were also carried out and the ratio of compressive strength and tensile strength was evaluated. The tensile strength determined by built-in cylinder tensile test was slightly higher than that by dumbbell type direct tensile test. The dumbbell type test has often failed in joint part of specimen and showed some difficulty to prepare a specimen. Among three tensile testing methods, the standard deviation of tensile strength by split tensile test was highest. It was shown that the split tensile test is applicable to concrete or rock with elastic failure but not for cemented soils having lower strength.

Aluminum autobody technology for the '90 (90년대의 Al 차체 기술)

  • 박석완;권순용;조원석
    • Journal of the korean Society of Automotive Engineers
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    • v.15 no.1
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    • pp.3-8
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    • 1993
  • 본 고에서는 차체제작의 첫단계인 프레스 성형시 문제가 되는 알루미늄 합금판재의 성형성에 대하여 기술한다. 차체용 Al합금판의 성형성을 인장시험, 헤밍시험, 스트레치 포오밍 시험 등으로 조사해 보았다. 냉연강판과 비교하여 현재의 차체용 Al합금판은 강도와 연신율 면에서 열세임에 틀림이 없으나, 앞으로 냉여강판에 버금가는 Al합금판이 나오리라 예상한다. 1. 시편의 종류. 2. 결정립 조직. 3. 집합 조직. 4. 상온 인장시험. 5. 고온 인장시험. 6. 헤밍시험(Hemming test). 7. 스트레치 포오밍 시험(Stretch forming test)

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Development of Mechanical Test Techniques for Irradiated Zircaloy Cladding in Hot Cell (조사 지르칼로이 피복관의 기계적 특성시험 기술 개발)

  • 김도식;홍권표;주용선;안상복;송웅섭;유병옥;김기하
    • Proceedings of the Materials Research Society of Korea Conference
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    • pp.213-213
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    • 2003
  • 고온 및 고압의 가혹한 방사선 분위기에서 사용되는 핵연료 피복관은 중성자 조사 및 수소화합물의 생성 등으로 인하여 기계적 성질이 저하된다. 따라서 조사된 핵연료 피복관의 손상기준 확립과 안전성 해석을 위해서는 연성 및 강도 등 기계적 특성을 정확히 이해하여야 할 필요가 있다. 핵연료 피복관의 종 및 횡 방향 인장특성 평가를 위하여 개발된 기존의 다양한 시험법들을 비교하고, 핫셀시험에 적합한 인장시험법을 개발하였다. 피복관의 종방향 인장시편은 튜브시편 또는 게이지부 내에서 균일한 변형률 분포를 얻도록 설계된 도그본 튜브시편(그림 1)을 사용한다. 피복관의 횡방향 인장시험에 사용되는 링시편(그림 2)은 게이지부 내에서 균일한 단축 원환변형율 분포 또는 평면변형율 조건을 나타내도록 설계한다. 연소 또는 조사된 피복관으로부터 시편을 제작하기 위해서는 핫셀 내에서 작업 이 가능한 방전가공기(그림 3)를 사용한다. 피복관의 종방향 인장시험용그립(grip)은 핀-부하형이며, 횡방향 인장시험의 경우는 시험 동안 시편의 곡률이 일정하게 유지 되도록 그립의 형상 및 치수를 결정한다(그림 4). 피복관의 종 및 횡방향 강도와 변형 등 기계적 특성을 평가하기 위한 응력-변형율 곡선은 시험기의 복합 강성(K)을 고려하여 결정한다. 이상과 같이 검토된 인장시험법은 피복관의 안전성 해석(safety analysis)과 관련 규정(regulatory)에서 사용되는 피복관 손상기준(fuel damage criteria)의 개선에 필수적인 자료를 제공한다.

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Tensile Strength Characteristics of Cement Paste Mixed with Fibers (섬유가 혼합된 시멘트 페이스트의 인장강도 특성에 관한 연구)

  • Park, Sung-Sik;Hou, Yaolong
    • Journal of the Korean Geotechnical Society
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    • v.31 no.3
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    • pp.5-16
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    • 2015
  • The characteristics of tensile strength of fiber-reinforced grouting (cement paste) injected into rocks or soils were studied. A tensile strength of such materials utilized in civil engineering has been commonly tested by an indirect splitting tensile test (Brazilian test). In this study, a direct tensile testing method was developed with built-in cylinder inside a cylindrical specimen with 15 cm in diameter and 30 cm in height. The testing specimen was prepared with 0%, 0.5%, or 1% (by weight) of a PVA or steel fiber reinforced mortar. A specimen with 5 cm in diameter and 10 cm in height was also prepared and tested for the splitting tensile test. Each specimen was air cured for 7 days or 28 days before testing. The tensile strength of built-in cylinder test showed 96%-290% higher than that of splitting tensile test. The 3D finite element analyses on these tensile tests showed that the tensile strength from built-in cylinder test had was 3 times higher than that of splitting tensile test. It is similar to experimental result. As an amount of fiber increased from 0% to 1%, its tensile strength increased by 119%-190% or 23%-131% for 7 days or 28 days-cured specimens, respectively. As a curing period increased from 7 days to 28 days, its strength decreased. Most specimens reinforced with PVA fiber showed tensile strength 14%-38% higher than that of steel fiber reinforced specimens.

The Suggestion of Testing Method for Analysis of Tensile Strength of Multi-Directional GFRP Plate (다방향 GFRP 플레이트의 인장강도 분석을 위한 시험 방법 제안에 관한 연구)

  • Sim, Jong-Sung;Kwon, Hyuck-Woo;Lee, Hyoung-Ho;Kim, Hyun-Joong
    • Journal of the Korea Concrete Institute
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    • v.23 no.6
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    • pp.799-808
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    • 2011
  • In this study, a standardized test method to analyze tensile properties of multi-directional GFRP plate was proposed. Presently, tensile strength test of FRP composite reinforced with isotropic and orthotropic fiber is standardized according to ISO standard. Also, even though many studies were performed on test method to analyze the dynamic properties, the properties of tensile strength for multi-directional GFRP plate were not clearly identified. Currently, the domestic test method in accordance with ASTM, which is applicable to unidirectional FRP plate, gave tensile test results greater than actual properties. Thus, in this study, GFRP tensile test was conducted using the method found to be commonly applicable to all standards based on literature review of domestic and international references. Then, anchorage length experiments were performed using the proposed tension test method to evaluate validity of the method. Finally, optimal anchorage length was estimated from the numerical analysis to propose the standardized tensile strength method for GFRP multi-directional composite evaluation.

Wide-Width Tensile Strength Properties of Geogrids according to Specimen Length and Testing Speed (시료크기 및 인장속도에 따른 지오그리드의 광폭인장강도 평가)

  • Cho, Sam-Deok;Lee, Kwang-Wu;Oh, Se-Yong
    • Journal of the Korean Geosynthetics Society
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    • v.6 no.2
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    • pp.21-26
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    • 2007
  • The tensile properties of geogrid are affected by such factors as temperature, specimen length, gauge length, testing speed and measuring equipment. The tensile strength of geogrids can be determined by ASTM 06637 and ISO 10319. The main differences between two testing methods are testing speed and specimen length. This paper presents the results of the wide-width tensile tests for three geogrids according to different specimen length and tension speed.

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Forming Limit Evaluation of Copper Alloy for Liquid Rocket Combustion Chamber (액체로켓 연소기용 구리합금의 성형한계성 평가)

  • Ryu, Chul-Sung;Choi, Hwan-Seok
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • pp.194-197
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    • 2007
  • The dome stretching and tension test have been made to obtain a forming limit curve(FLC) for the copper alloy which is used for manufacturing the regenerative cooling chamber. For experimental survey of the forming limit curve, we have used in-plane tension specimen to obtain tension-compression strain state and also out of plane specimen to obtain tension-tension strain state through dome stretching test. All specimens are divided into longitudinal and radial direction specimens by the manufacturing method. The test results shows that in tension-tension region, copper alloy possesses a maximum major strain of 62.3% and maximum minor strain of 58.6%. In the tension-compression region, maximum major strain is 60.5% and maximum minor strain is 25.8%.

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Characterization of Tensile Strength of Anisotropic Rock Using the Indirect Tensile Strength Test (간접인장강도시험을 통한 이방성 암석의 인장강도 특성)

  • 김영수;정성관;최정호
    • Journal of the Korean Geotechnical Society
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    • v.18 no.5
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    • pp.133-141
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    • 2002
  • Isotropic rock and anisotropic rock have different tensile strength which has the greatest influence on rock failure. In this study, elastic modulus of anisotropic rock is obtained through uniaxial compression test, and tensile strength and tension failure behavior are analyzed through indirect tensile strength test. Stress concentration factor of a specimen at the center is obtained from anisotropic elastic modulus and strain by indirect tensile strength test. Theoretical solutions for tensile strength of isotropic and anisotropic rock are compared. Stress concentration factor of anisotropic rock is either higher or lower than isotropic rock depending on the inclination angle of bedding plane. The use of stress concentration factor of isotropic rock resulted in overestimation or underestimation of tensile strength.

Experimental Evaluation Study on the Integrity of Plastic Shell Structure using Acoustic Emission Technique (음향방출기법을 응용한 플라스틱 쉘 구조물의 건전성 평가 연구)

  • Shul, Chang-Won;Lee, Kee-Bhum
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.33 no.12
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    • pp.39-47
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    • 2005
  • An acoustic emission technique is applied to the tensile tests of the plastic specimen under the different test speeds and the structural integrity evaluation of the plastic shell structure. Several AE characteristics are acquired from the tensile tests and they are proven to be useful parameters in evaluating its structural integrity. The results shows that tensile strength has almost constant value over some higher speed region while revealing some increasing tendency in strength as the test speeds up in lower speed region. The crack initiation loads and locations are accurately evaluated during the static compression testing of the plastic shell structures by using acoustic emission technique.