• Title/Summary/Keyword: Indentation Depth

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Stress Conversion Factor on Penetration Depth of Knoop Indentation for Assessment of Nano Residual Stress (나노 잔류응력 측정을 위한 비등방 압입자의 깊이별 응력환산계수 분석)

  • Kim, Won Jun;Kim, Yeong Jin;Kim, Young-Cheon
    • Journal of the Microelectronics and Packaging Society
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    • v.26 no.4
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    • pp.95-100
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    • 2019
  • Nanoindentation has been widely used for evaluating mechanical properties of nano-devices, from MEMS to packaging modules. Residual stress is also estimated from indentation tests, especially the Knoop indenter which is used for the determination of residual stress directionality. According to previous researches, the ratio of the two stress conversion factors of Knoop indentation is a constant at approximately 0.34. However, the ratio is supported by insufficient quantitative analyses, and only a few experimental results with indentation depth variation. Hence, a barrier for in-field application exists. In this research, the ratio of two conversion factors with variation in indentation depth using finite elements method has been attempted at. The magnitudes of each conversion factors were computed at uniaxial stress state from the modelled theoretical Knoop indenter and specimen. A model to estimate two stress conversion factor of the long and short axis of Knoop indenter at various indentation depths is proposed and analyzed.

Development and its Performance Evaluation of a Depth-Sensing Micro-Indentation Testing Device (깊이 측정이 가능한 마이크로 압입 시험기 개발 및 성능평가)

  • Chung, Chin-Sung;Kim, Ho-Kyung
    • Tribology and Lubricants
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    • v.25 no.3
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    • pp.163-170
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    • 2009
  • We developed a compact micro indentation testing device (designated SNUT) which is capable to measure Young's modulus of a sample using depth and applied load data during indentation. Performance of this device was evaluated using pure Ti, pure Ni, and die steel (SKD11). As a result of analysing the indentation test data, the frame compliance $C_f$ was found to influence mainly the modulus by 80% among several factors affecting accuracy of Young's modulus. Project area, which was determined by indirect indentation method, was modified using direct SEM observation. Finally, Young's modulus error was reduced to 5% after taking into consideration the frame compliance and modified projected area from 80% error without any these two correction factors. The performance of SNUT and MTS instruments was compared using same specimen (pure Ti).

Evaluation of Stress-Strain Characteristics of Weldment in Natural Gas Pipeline Using Advanced Indentation System (Advanced Indentation System을 이용한 천연가스배관 용접열영향부의 응력-변형률 변화 특성 분석)

  • Jang, Jae-Il;Son, Dong-Il;Kwon, Dong-Il;Kim, Woo-Sik;Park, Joo-Seung
    • Proceedings of the KSME Conference
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    • 2001.06a
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    • pp.483-488
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    • 2001
  • Until now, the tensile properties of materials can be obtained just in accordance with conventional tensile testing methods which are described in several standards such as ASTM (American Society for Testing and Materials) standard and BS (British Standard). For some cases including on-service facility materials, however, the standard testing methods cannot be applicable due to the destructive testing procedure and specimen size requirement. Therefore, simple, non-destructive and advanced indentation technique was proposed. This test measures indentation load-depth curve during indentation and analyzes the mechanical properties related to deformation and fracture. In this paper, the research trend of non-destructive evaluation of tensile properties using AIS (advanced indentation system) and its application fields are reviewed and discussed.

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Frictional characteristics of coating layer in diesel engine piston ring (디젤엔진 피스톤 링 코팅 층의 마찰특성)

  • Jang, J.H.;Joo, B.D.;Lee, H.J.;Kim, E.H.;Moon, Y.H.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2009.05a
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    • pp.294-297
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    • 2009
  • The frictional behaviors of Cermets/Cr-Ceramics and Cu-Al coatings of piston ring were investigated. Friction tests were carried out by pin-on-disk test and materials properties of coating layer were analyzed by nano indentation tester. Higher friction coefficient was obtained at harder coating with rougher surface. In case of hard-coating, the scratch depth, width and pile-up height had close relationship with indentation hardness. So the scratch width, depth and pile-up height increases with decreasing friction coefficient. But in case of soft-coating, the friction coefficients are strongly dependent on the morphological characteristics after nano scratching more than indentation hardness.

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Determination of Brinell Hardness through Instrumented Indentation Test without Observation of Residual Indent (계장화압입시험법을 이용한 비압흔관찰 브리넬 경도 평가)

  • Kim, Sung-Hoon;Choi, Yeol;Kwon, Dong-Il
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.28 no.5
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    • pp.578-585
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    • 2004
  • Hardness test is performed for determination of the other properties, such as strength, wear resistance and deformation resistance, as well as hardness itself. And it is performed for prediction of residual lifetime by analysis of hardness reduction or hardness ratio. However, hardness test has limitation that observation of residual indent is needed for determination of hardness value, and that is the reason for not to be widely used in industrial field. Therefore, in this study, we performed researches to obtain Brinell hardness value from quantitative numerical formula by analysing relationship between indentation depths from indentation load-depth curve and mechanical properties such as work hardening exponent, yield strength and elastic modulus.

An Evaluation of the Weldability Characteristics on the 4 Lap Spot Welded Joint of Structural Steel Sheets in Automobile (자동차용 강판의 4겹 다층 점용접물의 용접특성 평가)

  • Kim, Hoi-Hyun;Kim, Seong-Su;Baek, Seung-Se;Kwon, Il-Hyun;Yang, Seong-Mo;Yu, Hyo-Sun
    • Proceedings of the KSME Conference
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    • 2004.11a
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    • pp.314-318
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    • 2004
  • This research is conducted to investigate weldability characteristics with various welding conditions on the 4 lap spot welded joint of structural steel sheets in automobile. The relationship between the tensile-shear strength and the indentation depth has been investigated to evaluate the weldability and the optimum welding conditions. The welding current and the welding time have a greatly affect to the tensile-shear strength compared to the electrode force. It was found that the indentation depth has a relatively close relationship with the expulsion occurrence. The optimum welding conditions were proposed for the 4 lap spot welded joint.

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Evaluation of Thin Film Residual Stress through the Theoretical Analysis of Nanoindentation Curve (나노 압입곡선의 이론적 분석을 통한 박막의 잔류응력 평가)

  • Lee, Yun-Hee;Jang, Jae-Il;Kwon, Dong-Il
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.26 no.7
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    • pp.1270-1279
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    • 2002
  • Residual stress is a dominant obstacle to efficient production and safe usage of device by deteriorating the mechanical strength and failure properties. Therefore, we proposed a new thin film stress-analyzing technique using a nanoindentation method. For this aim, the shape change in the indentation load-depth curve during the stress-relief in film was theoretically modeled. The change in indentation depth by load-controlled stress relaxation process was related to the increase or decrease in the applied load using the elastic flat punch theory. Finally, the residual stress in thin film was calculated from the changed applied load based on the equivalent stress interaction model. The evaluated stresses for diamond-like carbon films from this nanoindentation analysis were consistent with the results from the conventional curvature method.

A Study on the Weldability & Indentation Depth Evaluation of Electrochemical Galvanized Steel Sheet according to the Welding Conditions (전기아연도금 강판의 점용접성에 미치는 용접조건과 압흔깊이에 관한 연구)

  • 정영훈;허우진;백승세;권일현;양성모;유효선
    • Proceedings of the KWS Conference
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    • 2003.11a
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    • pp.162-164
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    • 2003
  • Spot welding, a kind of electric resistance welding, has been used in many fields such as automobile, aircraft, and appliance industry. This paper is to investigate the relationship between tensile shear strength and indentation depth under various welding conditions. The tensile shear strength increases with increasing the welding current in the range of 6-l3kA. The optimum welding conditions were 200∼250kg welding force and 10∼15 cycles welding time at 9kA welding current for EZNCEN. The indentation depth for optimum welding condition was 0.6mm at 9kA welding curent and 200kg welding force, 0.17mm at 9kA welding current and 300kg welding force, 0.19mm at 9kA welding current and 10cycle, 0.17mm at 9kA welding current and 15cycle welding time, respectively.

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Application of Advanced Indentation System for Evaluati Tensile Property Degradation of Cr-Mo Steel (Cr-Mo 강의 열화도 평가를 위한 Advanced Indentation System의 응용)

  • Jang, Jae-Il;Choi, Yoel;Lee, Yun-Hee;Kwon, Dong-Il;Kim, Jeoung-Tae
    • Proceedings of the KSME Conference
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    • 2001.06a
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    • pp.231-236
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    • 2001
  • A newly developed Advanced Indentation System (AIS), which is a portable and nondestructive system for evaluating tensile properties, was used to measure mechanical behavior of materials used under high temperature and pressure conditions. This test measures indentation load-depth curve during indentation and analyzes the mechanical properties related to deformation and fracture. Aging effects of Cr-Mo and Cr-Mo-V steel at high temperature were simulated. Tensile properties including yield strength and tensile strength at various temperature are obtained from the test. For all test materials and conditions, the AIS-derived results were in good agreement with those from conventional standard test method. Examples of the test results ate given and potential applications of the AIS to assess the integrity of aging structures are briefly discussed.

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Evaluation of Flow Properties of Steel Using Advanced Indentation System (비파괴적 연속압입시험 기법을 응용한 구조용 강의 소성 물성 평가)

  • Jang, J.I.;Son, D.I.;Choi, Y.;Park, S.C.;Kwon, D.I.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2002.05a
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    • pp.191-194
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    • 2002
  • The tensile properties of materials can be obtained just in accordance with conventional tensile testing methods which are described in several standards. However, the standard testing methods cannot be applicable due to the destructive testing procedure and specimen size requirement for some cases including on-service facility materials. Therefore, simple, non-destructive and advanced indentation technique was proposed. This test measures indentation load-depth curve during indentation and analyzes the mechanical properties related to deformation and fracture. In this paper, the research trend of non-destructive evaluation of tensile properties using advanced indentation system and its application fields are reviewed and discussed.

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