• Title/Summary/Keyword: Instrumented Indentation Tests

Search Result 21, Processing Time 0.024 seconds

Hardness Estimation of Compressor Journal for a Use of Instrumented Indentation Techniques (계장화 압입시험법을 이용한 차량용 컴프레서 저널 경도 평가)

  • Kwak, Sung-Jong;Jin, Ji-Won;Kim, Tae-Seong;Noh, Ki-Han;Kang, Ki-Weon
    • Journal of the Korean Society of Manufacturing Technology Engineers
    • /
    • v.21 no.3
    • /
    • pp.376-381
    • /
    • 2012
  • This paper deals with application of instrumented indentation technique for quality inspection methodology for automobile component. For this, the instrumented indentation tests were performed the normal and cracked compressor journal, which is made from spheroidal graphite cast iron and utilized in air-conditioning system. And the Brinell hardness was estimated using the unloading slope and maximum indentation force. With the aid of Normal distribution, this Brinell hardness was statistically compared and analyzed with hardness measured by indentation hardness tests. Also, application possibility of reliability-based quality inspection criteria for compressor journal was evaluated through the probabilistic analysis for the Brinell hardness estimated by instrumented indentation technique.

A Study on the Unloading Stiffness of Instrumented Indentation Tests (계장화 압입 시험에서 하중 제거 곡선의 강성률에 관한 고찰)

  • 이병섭;이호진;이봉상
    • Transactions of Materials Processing
    • /
    • v.13 no.1
    • /
    • pp.21-26
    • /
    • 2004
  • Instrumented indentation tests have been used for estimating material properties. In order to analyze deformation characteristics with various factors, the unloading stiffness should be properly determined from the elastic behavior. The unloading stiffness is generally obtained from the shifted power functions fitting with the experimental unloading data. However, the functions often give rise to a poor representation of actual data, and also the unloading stiffness is governed by unloading condition. In this study, both numerical and experimental conditions to obtain proper unloading stiffness were investigated. The result showed that the amount of unloading ratio and hold time played an important role in fitting the unloading curves. The current efforts can successfully provide the unloading stiffness for indentation material properties.

A Study on the Unloading Stiffness of Instrumented Indentation Tests (압입시험에서 하중제하곡선의 강성율에 관한 고찰)

  • 이병섭;이호진;이봉상
    • Proceedings of the Korean Society for Technology of Plasticity Conference
    • /
    • 2003.10a
    • /
    • pp.168-171
    • /
    • 2003
  • Instrumented indentation tests have been used for estimating material properties. In order to analyze deformation characteristics with various factors, the unloading stiffness should be properly determined from the elastic behaviour. In general, the unloading stiffness is obtained from shifted power functions fitting to indentation unloading curves. But, the functions give often a poor representation of actual data. In this study, control conditions for fitting unloading curves by shifted power functions were investigated. The current efforts may provide useful information about unloading process and valid unloading stiffness.

  • PDF

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
    • /
    • v.36 no.9
    • /
    • pp.1081-1086
    • /
    • 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.

Prediction of State of Cutting Surfaces of Polymers by Analysis of Indentation Load-depth Curve (압입하중-변위곡선 분석을 통한 폴리머 소재의 절삭표면상태 예측에 관한 연구)

  • Jeon, Eun-Chae;Kim, Jae-Hyun;Je, Tae-Jin
    • Journal of the Korean Society of Manufacturing Process Engineers
    • /
    • v.10 no.4
    • /
    • pp.76-81
    • /
    • 2011
  • UV imprinting process can manufacture high-functional optical components with low cost. If hard polymers can be used as transparent molds at this process, the cost will be much lower. However, there are limited researches to predict the machinability and the burr of hard polymers. Therefore, a new method to predict them by analyzing load-depth curves which can be obtained by the instrumented indentation test was developed in this study. The load-depth curve contains elastic deformation and plastic deformation simultaneously. The ratio of the plastic deformation over the sum of the two deformation is proportional to the ductility of materials which is one of the parameters of the machinability and the burr. The instrumented indentation tests were performed on the transparent molds of the hard polymers and the values of ratio were calculated. The machinability and the burr of three kinds of hard polymers were predicted by the ratio, and the prediction was in agreement with the experimental results from the machined surfaces of the three kinds of hard polymers.

Influence of Indenter Tip Geometry and Poisson's Ratio on Load-Displacement Curve in Instrumented Indentation Test (계장화 압입시험의 하중-변위 곡선에 미치는 선단 형상 및 푸아송비의 영향)

  • Lee, Jin Haeng
    • Transactions of the Korean Society of Mechanical Engineers A
    • /
    • v.38 no.9
    • /
    • pp.943-951
    • /
    • 2014
  • The tip geometries of the pyramidal and conical indenters used for micro/nano-indentation tests are not sharp. They are inevitably rounded because of their manufacturability and wear. In many indentation studies, the tip geometries of the pyramidal indenters are simply assumed to be spherical, and the theoretical solution for spherical indentation is simply applied to the geometry at a shallow indentation depth. This assumption, however, has two problems. First, the accuracy of the theoretical solution depends on the material properties and indenter shape. Second, the actual shapes of pyramidal indenter tips are not perfectly spherical. Hence, we consider the effects of these two problems on indentation tests via finite element analysis. We first show the relationship between the Poisson's ratio and load-displacement curve for spherical indentation, and suggest improved solutions. Then, using a possible geometry for a Berkovich indenter tip, we analyze the characteristics of the load-displacement curve with respect to the indentation depth.

Instrumented Indentation Technique: New Nondestructive Measurement Technique for Flow Stress-Strain and Residual Stress of Metallic Materials (계장화 압입시험: 금속재료의 유동 응력-변형률과 잔류응력 평가를 위한 신 비파괴 측정 기술)

  • Lee, Kyung-Woo;Choi, Min-Jae;Kim, Ju-Young;Kim, Kwang-Ho;Kwon, Dong-Il
    • Journal of the Korean Society for Nondestructive Testing
    • /
    • v.26 no.5
    • /
    • pp.306-314
    • /
    • 2006
  • Instrumented indentation technique is a new way to evaluate nondestructive such mechanical properties as flow properties, residual stress and fracture toughness by analyzing indentation load-depth curves. This study evaluated quantitatively the flow properties of steels and residual stress of weldments. First, flow properties can be evaluated by defining a representative stress and strain from analysis of deformation behavior beneath the rigid spherical indenter and the parameters obtained from instrumented indentation tests. For estimating residual stress, the deviatoric-stress part of the residual stress affects the indentation load-depth curve, so that by analyzing the difference between the residual-stress-induced indentation curve and residual-stress-free curve, the quantitative residual stress of the target region can be evaluated. The algorithm for flow property evaluation was verified by comparison with uniaxial tensile test and the residual stress evaluation model was compared to mechanical cutting and ED-XRD results.

Determination of Mechanical Properties of Galvanized Steel Sheets Using Instrumented Indentation Technique and Finite Element Analysis (계장화 압입시험 및 유한요소해석을 이용한 아연도금강판의 기계적 물성 추정)

  • Jin, Ji-Won;Kwak, Sung-Jong;Kim, Tae-Seong;Noh, Ki-Han;Kang, Ki-Weon
    • Transactions of the Korean Society of Mechanical Engineers A
    • /
    • v.36 no.5
    • /
    • pp.529-535
    • /
    • 2012
  • This paper deals with the determination of mechanical properties of various galvanized steel sheets that are used for fabricating automobile bodies; the instrumented indentation technique and finite element analysis were used for the determination. First, tensile tests were conducted to obtain the true stress-true strain curves of galvanized steel sheets with various thicknesses. Load-deformation curves were then obtained by using the instrumented indentation testing machine, and they were compared with load-deformation curves obtained by finite element analysis. Further, true stress-true strain curves were obtained at the optimal observation point by finite element analysis.

A Study on Low-Velocity Impact Characterization of Sandwich Panels with Metal and Laminate Composite Facesheets (금속재와 적층복합재 면재를 갖는 샌드위치 패널의 저속충격 특성 연구)

  • Lee, Jae-Youl;Lee, Sang-Jin;Jo, Se-Hyun;Mok, Jai-Kyun;Shin, Kwang-Bok
    • Proceedings of the KSR Conference
    • /
    • 2007.05a
    • /
    • pp.144-150
    • /
    • 2007
  • In this paper, the low velocity response of four different sandwich panels with metal and laminate composite facesheets has been investigated by conducting drop-weight impact tests using an instrumented falling-weight impact tower. Square samples of 100mm sides were subjected low-velocity impact loading using an instrumented testing machine at six energy levels. Impact parameters like maximum force, time to maximum force, deflection at maximum force and absorbed energy were evaluated and compared for four different types of sandwich panels. The impact test results show that sandwich panel with composite laminate facesheet could not observe damage mode of a permanent visible indentation after impact and has a good impact damage resistance in comparison with sandwich panel with metal aluminum facesheet.

  • PDF

Mechanical Characteristics of Automobile Brake Pads (자동차 브레이크 패드의 기계적 특성 연구)

  • Shin, Jaeho;Kim, Kyungjin;Kang, Woojong
    • Journal of Auto-vehicle Safety Association
    • /
    • v.7 no.3
    • /
    • pp.19-24
    • /
    • 2015
  • Brake pads are a component of disc brake system of automobile and consist of steel backing plates and friction material facing the disk brake rotor. Due to the repeated sliding forces and torque in vehicle braking, friction performance of brake pads are ensured. Futhermore, the brake pad is one of major tuning components in aftermarket, mechanical characteristics of the brake pad are necessary to evaluate for establishing the certification standards of tuning components. This study had performed the five specimen tests for friction coefficients and wear loss rates according to the SAE test specification. Using the instrumented indentation method, yield strength and tensile strength were measured. Friction coefficients, 0.386 - 0.489, and wear loss rates, 1.0% - 3.7% are obtained. The range of yield strength and tensile strength are 21.4 MPa - 105.3 MPa and 39.5 MPa - 176.4 MPa respectively.