• Title/Summary/Keyword: Indentation Technique

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Evaluation of Residual Stress on Welded Joint in API X65 Pipe Line through Nondestructive Instrumented Indentation Technique (비파괴 계장화 압입시험기법을 통한 API X65 배관 용접부 잔류응력 평가)

  • 지원재;이윤희;김우식;김철만;권동일
    • Journal of Welding and Joining
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    • v.21 no.5
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    • pp.547-554
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    • 2003
  • Apparent mechanical properties in structural components can be different from the initially designed values due to the formation of the residual stress in metal forming and welding. Therefore, the evaluation of residual stress has great importance in the reliability diagnosis of structural components. A nondestructive instrumented indentation technique has been proposed to evaluate various strength concerning mechanical properties from the analysis of load-depth curve. In this study, quantitative residual stress estimation on API X65 welded joints for natural gas pipeline was performed by analyzing the variation of indentation loading curve by residual stress through a new proposed theoretical model. The residual stress from the indentation method was compared with that from the saw-cutting method.

Characterization of Elastic Modulus and Work of Adhesion in Elastomeric Polymer through Micro Instrumented Indentation Technique (마이크로 압입시험기법의 응용을 통한 탄성체 고분자 소재의 역학적 특성화 및 계면 접합에너지 평가기법 연구)

  • Lee, Gyu-Jei;Kang, Seung-Kyun;Kang, In-Geun;Kwon, Dong-Il
    • Proceedings of the KSME Conference
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    • 2007.05a
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    • pp.1744-1748
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    • 2007
  • In this study, the Johnson-Kendall-Roberts (JKR) theory was combined with the instrumented indentation technique (IIT) to evaluate work of adhesion and modulus of elastomeric polymer. Indentation test was used to obtain the load-displacement data for contacts between Tungsten Carbide indenter and elastomeric polymer. And the JKR contact model, contrived to take viscoelastic effects of polymer into account, was applied to compensate the contact area and the elastic modulus which Hertzian contact model would underestimate and overestimate, respectively. Besides, we could obtain the thermodynamic work of adhesion by considering the surface energy in this contact model. In order to define the relation between JKR contact area and applied load without optical measuring of contact area, we used the relation between applied load and contact stiffness by examining the correlation between JKR contact area and stiffness through dimensional analysis with 14 kinds of elastomeric polymer. From this work, it could be demonstrated that the interfacial work of adhesion and elastic modulus of compliant polymer can be obtained from a simple instrumented indentation testing without area measurement, and provided as the main algorithm of compliant polymer characterization.

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Mechanical Characterization of Elastomeric Polymer Through Micro Instrumented Indentation Technique (마이크로 압입시험기법의 응용을 통한 탄성체 고분자 소재의 역학적 특성화 및 계면 접합에너지 평가기법 연구)

  • Lee, Gyu-Jei;Kang, Seung-Kyun;Kang, In-Geun;Kwon, Dong-Il
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.31 no.9
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    • pp.951-959
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    • 2007
  • In this study, the Johnson-Kendall-Roberts(JKR) theory was combined with the instrumented indentation technique (IIT) to evaluate work of adhesion and modulus of elastomeric polymer. Indentation test was used to obtain the load-displacement data for contacts between Tungsten Carbide indenter and elastomeric polymer. And the JKR contact model, contrived to take viscoelastic effects of polymer into account, was applied to compensate the contact area and the elastic modulus which Hertzian contact model would underestimate and overestimate, respectively. Besides, we could obtain the thermodynamic work of adhesion by considering the surface energy in this contact model. In order to define the relation between JKR contact area and applied load without optical measuring of contact area, we used the relation between applied load and contact stiffness by examining the correlation between JKR contact area and stiffness through dimensional analysis with 14 kinds of elastomeric polymer. From this work, it could be demonstrated that the interfacial work of adhesion and elastic modulus of compliant polymer can be obtained from a simple instrumented indentation testing without area measurement, and provided as the main algorithm of compliant polymer characterization.

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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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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Measurement of Biomechanical Property of Chondrocyte (연골세포의 기계적 물성치 측정)

  • ;Daehwan Shin
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2002.05a
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    • pp.154-157
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    • 2002
  • A cyto-indentation technique was used to obtain the biomechanical compressive compliance property of an chondrocyte cell attached to glass surface, which was tried to generate joint cartilage by tissue engineering. Piezo-transducer system and dual photo-diode system were used to conduct mechanical indentation through displacement-controlled testing and the measurement of corresponding cell reaction force. The Poisson's ratio of 0.37 was quoted from other report. The compressive compliance of chondrocyte, that was determined by elastic contact theory, was 1.38${\pm}$0.057 kPa. This value is 30% higher than that of MG63 osteoblast-like cell. The cyto-indentation technique employed in this study is so precise that it can quantify the biomechanical property of single cell.

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Hardness Evaluation of Spot Welding Using Instrumented Indentation Technique (계장화 압입시험법을 이용한 점용접부의 경도평가)

  • Jin, Ji-Won;Kwak, Sung-Jong;Yoo, Dong-Ok;Kim, Tae-Seong;Kang, Ki-Weon
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.36 no.9
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    • pp.1081-1086
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    • 2012
  • This study deals with hardness evaluation for spot welding by using an instrumented indentation technique to improve the quality of the inspection methodology. First, an instrumented indentation test and a Rockwell hardness test were performed for normal and abnormal spot welding. The hardness to indentation force-displacement curve obtained using each of the tests was compared. Furthermore, an analysis was conducted using the hardness obtained by the instrumented indentation technique. A quality control standard based on reliability was this evaluated for spot welding.

Crack Growth Retardation Behavior in Aluminium 2024-T3 Alclad Alloy by Pre-Indentation (예비압입에 의한 알루미늄 2024-T3 알클래드 합금의 균열성장 지연거동)

  • 황정선;조환기
    • Journal of the Korea Institute of Military Science and Technology
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    • v.4 no.2
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    • pp.42-51
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    • 2001
  • The effects of pre-indentation technique are presented for A12024-T3 Alclad alloy using as skin material for aircraft fuselage and wing. Indentations were applied to specimens to be placed on the presumed path of fatigue crack growth before fatigue tests. Tension-tension fatigue tests were conducted on the edge cracked specimens in the L-T orientation. Test results were analyzed to investigate the effectiveness of pre-indentation with the variation of specimen's thickness, position of indentation and applied maximum stress. Fatigue crack retardation by pre-indentation is well recognized in the various conditions.

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In-field Evaluation of Structural Strength and Reliability Using Advanced Indentation System (Advanced Indentation System을 이용한 현장에서의 구조강도 건전성 평가)

  • Choi, Yeol;Son, Dong-Il;Jang, Jae-Il;Kwon, Dong-Il
    • Proceedings of the KSR Conference
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    • 2001.05a
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    • pp.230-237
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    • 2001
  • For the structural integrity of large and complex structures such as railway vehicle, the in-field diagnosis of mechanical properties of the structures is needed, and especially, the mechanical characteristics of the weldment must be carefully evaluated. But, conventional standard testing methods having destructive procedures are not applicable to in-field assessment of mechanical property variations within weldment because they needs the limitations of specimen size and geometry. In this paper, to overcome this problems, the advanced indentation technique (AIS) is introduced for simple and non-destructive/in-field testing of weldment of industrial structures. This test measures indentation load-depth curve during indentation and analyzes the mechanical properties related to deformation and fracture. First of all, flow properties such as yield strength, tensile strength and work hardening index can be evaluated through the analysis of the deformation behavior beneath the spherical indenter. Additionally, case studies of advanced indentation techniques are introduced.

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The study on properties of AAO(Anodic Aluminum Oxide) structures using nano indentation (나노 인텐테이션을 이용한 산화알루미늄(AAO, Anodic Aluminum Oxide)구조물의 물성치에 대한 연구)

  • Ko, Seung-Hyun;Lee, Dae-Woong;Jee, Sang-Eun;Park, Hyun-Chul;Lee, Kun-Hong;Hwang, Woong-Bong
    • Proceedings of the KSME Conference
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    • 2004.04a
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    • pp.144-149
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    • 2004
  • Porous anodic alumina has been used widely for corrosion protection of aluminum surfaces or as dielectric material in micro-electronics applications. It exhibits a homogeneous morphology of parallel pores which can easily be controlled between 10 and 400nm. It has been applied as a template for fabrication of the nanometerscale composite. In this study, mechanical properties of the AAO structures are measured by the nano indentation method. Nano indentation technique is one of the most effective method to measure the mechanical properties of nano-structures. Basically, hardness and elastic modulus can be obtained by the nano-indentation. Using the nano-indentation method, we investigated the mechanical properties of the AAO structure with different size of nano-holes. In results, we find the hole effect that changes the mechanical properties as size of nano hole.

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