• 제목/요약/키워드: Indentation Technique

검색결과 146건 처리시간 0.029초

조사된 미소 시편의 마모와 피로 거동을 평가하기 위한 동적 압침법 (Application of Kinetic Indentation Technique to Estimate Wear and Fatigue Behaviors of Irradiated Small Specimens)

  • V. Alyokhin;Y.S. Pyun;C.H. Hahn;Park, Y.
    • 한국표면공학회:학술대회논문집
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    • 한국표면공학회 2002년도 춘계학술발표회 초록집
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    • pp.38-38
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    • 2002
  • Kinetic indentation technique was studied and a method to evaluate wear and fatigue behaviors of irradiated small specimen was suggested. The method is based on both the proportion of elastic and plastic deformation and values obtained by micro-hardness test. The parameters obtained from the diagram of load-indentation depth-time are required to evaluates wear and fatigue properties. Considering the irradiated test specimen, it is one of possible and useful methods to estimate the irradiated wear and fatigue behaviors of the small size specimen. This article briefly describes the status of irradiated material study in domestic research reactor.

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연속압입 시험기법을 이용한 석유화학설비 경년손상의 새로운 평가변수 고찰 (Determination of New Parameter for Materials Degradation Using Continuous Indentation Testing Technique)

  • 장재일;최열;손동일;이윤희;권동일;김정태
    • 대한기계학회논문집A
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    • 제26권5호
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    • pp.881-889
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    • 2002
  • Newly developed continuous indentation technique has made nondestructive assessment of tensile properties possible. The present study was undertaken to determine new parameters for indicating time-dependent material degradation of petro-chemical plant. Continuous indentation tests were performed for Cr-Ni steel and Cr-Mo steel which are widely used as facilities of petro-chemical plant. From the results, it was found that yield strength and tensile strength cannot be used as general degradation parameters because the changes in the strengths with aging time didn't show any tendency. On the other hand, work hardening exponent and yield ratio showed consistent tendency with increasing aging time. Therefore, nam attention of this work was paid on them as new degradation parameters, and the in-field applicability of the parameters was evaluated and discussed.

압입법을 이용한 1Cr-1Mo-0.25V강의 열화도 평가에 관한 연구 (A study on the Evaluation of Material Degradation of 1Cr-1Mo-0.25V Steel using Ball Indentation Method)

  • 석창성;김정표;안하늘
    • 한국정밀공학회지
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    • 제18권4호
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    • pp.151-159
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    • 2001
  • As huge energy transfer systems like a nuclear power plant, steam power plant and petrochemical plant are operated for a long time, mechanical properties are changed by degradation. The life time of the systems can be affected by the mechanical properties. BI(Ball Indentation) test has a potential to replace conventional fracture tests like a uniaxial tensile test, fracture toughness test, hardness test and so on. In this paper, we would like to present the ageing evaluation technique by the BI method. The four classes of the thermally aged 1Cr-!mo-0.25V specimens were prepared using an artificially accelerated aging method. Tensile tests, fracture toughness tests, hardness tests and BI tests were performed. The results of the BI tests were in good agreement with fracture characteristics by a standard fracture test method within 5%. The IDE(Indentation Deformation Energy) of a BI technique as a new parameter for evaluating a degradation was suggested and the new IDE parameter clearly depicts the degradation degree.

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실험적 응력해석의 IITC 방식에 의한 콘크리트 구조물 잔류응력 평가 (Evaluation of Residual Stress using IITC of Experimental Stress Analysis on Concrete Structure)

  • 이호범;한상희;장일영
    • 대한토목학회논문집
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    • 제34권2호
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    • pp.415-424
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    • 2014
  • 기존 콘크리트 구조물 내력은 변위 및 스트레인 게이지를 통해 기지의 가력에 따른 변화량을 계측하고, 그 결과를 수치해석 결과와 비교하여 평가한다. 이는 결과적으로 현존 콘크리트의 잔류응력을 계측 평가하므로써 완성될 수 있다. 본 논문은 실험적 응력해석법의 일환으로 콘크리트 구조물에 대한 잔류응력을 비파괴적인 방식으로 평가하는 IITC (Instrumented Indentation Technique for Concrete) 시스템 개발과 관련된 것으로 콘크리트 구조물 표면에서 압입하중과 압입깊이와의 상관관계를 이용한 실험적 평가방법을 논하였다. 본 연구에서는 구성되는 H/W 및 분석용 S/W는 새롭게 개발하였으며, 다각도의 실험결과를 이용하여 콘크리트 구조물에서의 실험적 잔류응력 추정식을 창출하였고, 자동으로 잔류응력을 평가케 함으로써 콘크리트 구조물의 축성단계에서부터 유지관리 단계에까지 자유롭게 내력을 산정할 수 있도록 하였다.

Spherical Indentation Testing에 의한 1Cr-1Mo-0.25V 강의 기계적 물성 평가 (Spherical Indentation Testing to Evaluate Mechanical Properties In 1Cr-1Mo-0.25V Steel)

  • 이종민;남영현;남승훈;이승석;이억섭
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2001년도 추계학술대회논문집A
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    • pp.266-271
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    • 2001
  • Spherical indentation technique was developed to evaluate the flow properties of metallic materials in carbon steel, stainless steel and alloys, etc. Through the spherical indentation test, differently degraded 1Cr-1Mo-0.25V steel's mechanical properties were observed and compared with conventional standard test data. The flow properties of 1Cr-1Mo-0.25V steels were estimated by analyzing the indentation load-depth curve. To characterize the flow property, we used material yield slope and constraint factor index rather than strain-hardening exponent because the variation of strain-hardening exponent was very little and the data showed irregularly. And the constraint factor's effect was small when the material yield slope was taken into account.

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비파괴 계장화 압입시험을 이용한 저항 점용접부 물성 평가 (Evaluation of Mechanical Properties by Using Instrumented Indentation Testing for Resistance Spot Welds)

  • 최철영;김준기;홍재근;염종택;박영도
    • 한국분말재료학회지
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    • 제18권1호
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    • pp.64-72
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    • 2011
  • Nondestructive instrumented indentation test is the method to evaluate the mechanical properties by analyzing load - displacement curve when forming indentation on the surface of the specimen within hundreds of micro-indentation depth. Resistance spot welded samples are known to difficult to measure the local mechanical properties due to the combination of microstructural changes with heat input. Particularly, more difficulties arise to evaluate local mechanical properties of resistance spot welds because of having narrow HAZ, as well as dramatic changed in microstructure and hardness properties across the welds. In this study, evaluation of the local mechanical properties of resistance spot welds was carried out using the characterization of Instrumented Indentation testing. Resistance spot welding were performed for 590MPa DP (Dual Phase) steels and 780MPa TRIP (Transformation Induced Plasticity) steels following ISO 18278-2 condition. Mechanical properties of base metal using tensile test and Instrumented Indentation test showed similar results. Also it is possible to measure local mechanical properties of the center of fusion zone, edge of fusion zone, HAZ and base metal regions by using instrumented indentation test. Therefore, measurement of local mechanical properties using instrumented indentation test is efficient, reliable and relatively simple technique to evaluate the tensile strength, yield strength and hardening exponent.

계장화 압입시험을 이용한 차륜의 강도평가 (The Strength Evaluation of Wheel for Railway Rolling Stock Using Instrumented Indentation Test)

  • 김철수;안승호;정광우;박신호;강길현
    • 한국철도학회:학술대회논문집
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    • 한국철도학회 2007년도 춘계학술대회 논문집
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    • pp.1607-1612
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    • 2007
  • To assure safe usage of railway rolling stock, it is important to evaluate the strength of the wheel which is core part in bogies. However, conventional standard testing methods using destructive technique could not evaluate mechanical properties of degraded wheels during rolling stock maintenance work. Instrumented indentation test is a new way to evaluate nondestructively the strength of mechanical components by analyzing indentation load-depth curves. In this study, to evaluate tensile strength of the wheel, instrumented indentation test is performed nondestructively according to KS B 0950. Furthermore, test results are examined by tensile test in accordance with KS R 9221.

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Study on the Elastic Characteristics of Living Cells using Atomic Force Microscope Indentation Technique

  • Kwon Eun-Young;Kim Young-Tae;Kim Dae-Eun
    • KSTLE International Journal
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    • 제7권1호
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    • pp.10-13
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    • 2006
  • In this work, imaging and study of elastic property of the living cell was performed. The motivation of this work was to seek the possibility of exploiting Young's modulus as a disease indicator using Atomic Force Microscope (AFM) and also to gain fundamental understanding of cell mechanics for applications in medical nanorobots of the future. L-929 fibroblast adherent cell was used as the sample. Imaging condition in cell culturing media environment was done in very low speed ($20{\mu}m/ s$) compared to that in the ambient environment. For measuring the Young's modulus of the living cell, AFM indentation method was used. From the force-distance curve obtained from the indentation experiment the Young's modulus could be derived using the Hertz model. The Young's modulus of living L-929 fibroblast cell was $1.29{\pm}0.2$ kPa.

응력완화 경로분석과 압입자/시편간 접촉형상 모델링에 바탕한 박막재료의 국소 잔류응력 평가 (Evaluation of Thin Film Residual Stress through the Analysis of Stress Relaxation Path and the Modeling of Contact Morphology)

  • 이윤희;김성훈;장재일;권동일
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2001년도 춘계학술대회논문집A
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    • pp.237-242
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    • 2001
  • Residual stress is a dominant obstacle to efficient production and safe usage of products by reducing the mechanical strength and failure properties. Especially, it causes interfacial failure and substrate deflection in the case of thin film. So, the exact evaluation and optimum control of thin film residual stress is indispensable. However, hole drilling or X-ray diffraction techniques have some limits in application to thin film. And, curvature technique for thin film materials cannot give the information about local stress variation. Therefore, we applied the nanoindentation technique in evaluating the thin film residual stress. In this study, we modeled the change of indentation loading curve for residually stressed and stress-free thin films during stress relaxation. The value of residual stress was directly related to the indentation depth change by relaxation. The residual stress from nanoindentation analysis was consistent with the result from curvature technique.

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FASTENER HOLE 모델의 대한 예비압입 적용 연구 (A Study on the Application of Pre-Indentation Technique for Fastener Hole Model)

  • 황정선;조환기
    • 한국항공우주학회지
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    • 제31권9호
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    • pp.26-31
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    • 2003
  • 노후 항공기는 일반적으로 다중손상(MSD)이라고 하는 폭넓게 분포된 피로손상을 내포하고 있다. 2024-T3 알루미늄합금과 같은 연성재료에 있어서 다중손상은 전통적인 파괴역학에서 예측할 수 있는 것보다 낮은 운용수명을 예측하게 만드는 것으로 알려져 있다. 본 논문에서는 다중손상을 갖는 평판 구조물을 모델링한 Fastener Hole을 갖는 2024-T3 알루미늄합금 판재로 제작된 Hole/Slot type M(T) 시편에 예입압입을 적용한 후 피로시험을 수행하여 피로균열 성장지연에 의한 운용수명 증가에 대한 효과를 연구하였다. 예비압입을 적용한 시편은 파단에 이르는 사이클수가 최소 10배에서 최대 40배까지 증가하였으며, 일정진폭 하중의 최대값을 증가시킴에 따라서 그 효과가 감소함을 보여주었다. 또한, 압입에 의한 균열성장지연 메커니즘은 균열진전경로가 압입자국에 들어서면서 균열성장률이 감소하기 시작하며 압입자국의 중심을 지나면서 최소균열성장률 상태로 일정한 시간동안 균열성장이 정체됨으로써 피로수명이 연장됨을 밝혔다.