• Title/Summary/Keyword: 압입시험

Search Result 200, Processing Time 0.029 seconds

압입시험 기법을 이용한 인장물성 평가

  • Kim, Sung-Hoon;An, Jung-Hoon;Choi, Yeol;Jeon, Eun-Chae;Kwon, Dong-Il
    • Proceedings of the Korean Institute of Industrial Safety Conference
    • /
    • 2000.11a
    • /
    • pp.3-8
    • /
    • 2000
  • 현재 재료의 기계적 특성을 평가하기 위한 가장 표준화된 방법은 일축인장시험이다. 일축인장시험은 다양한 기계적 물성을 제공하나, 일정 크기 이상의 시편을 요구하므로 실제 산업현장에서 사용되고 있는 구조물의 안전성 평가에 이용하기 어렵다. 이러한 단 점을 개선할 수 있는 시험법으로 최신압입시험법이 제안되었다.(중략)

  • PDF

A Study on Residual Strength of Carbon/Epoxy Face Sheet and Honeycomb Core Sandwich Composite Structure after Quasi Static Indentation Damage (탄소섬유/에폭시 면재, 알루미늄 허니컴 코어 샌드위치 복합재 구조의 압입 손상에 의한 잔류강도 연구)

  • Kong, Chang-Duk;Park, Hyun-Bum;Lee, Seoung-Hyun
    • Composites Research
    • /
    • v.22 no.2
    • /
    • pp.24-29
    • /
    • 2009
  • This study aims to investigate the residual strength of sandwich composites with Al honeycomb core and carbon fiber face sheets after the quasi-static indentation damage by the experimental investigation. The 3-point bending test and the edge-wise compressive strength test were used to find the mechanical properties, and the quasi-static point load was applied to introduce the simulated damage on the specimen. The damaged specimens were finally assessed by the 3-point bending test and the compressive strength test. The investigation results revealed the residual strength of the damaged specimens due to the quasi-static indentation. The both test results showed that the residual strength of the damaged specimen was decreased according to increases of the damaged depth.

Elastic and plastic behaviors of materials during the nanoindentation testing (나노인덴테이션 시험시 재료의 탄성.소성 변형거동)

  • 김지수;윤존도;김봉섭;고철호;이홍림;양현윤;조상봉
    • Proceedings of the Materials Research Society of Korea Conference
    • /
    • 2003.03a
    • /
    • pp.244-244
    • /
    • 2003
  • 나노인덴테이션은 시편에 압자를 침투시켜 재료의 기계적 특성을 파악할 수 있는 경도시험법이다. 압입범위를 나노미터범위로 조절할 수 있어 기존에 접근할 수 없었던 극 미소부분에로 응용이 넓어지고 있다. 경도시험시 재료의 탄성 및 소성 작용에 의해 재료는 변형되고, 표면변화 관찰을 통해 표면아래 부분에서 이루어지고 있는 거동을 예측할 수 있다. 이러한 관점에서 나노인덴테이션 시험시에도 발생하는 파일업과 싱크인 현상에서 재료가 나노미터 범위에서 어떠한 양상으로 변형을 하는지를 고찰하는 것은 의미가 있을 것이다. 본 연구에서 파일업과 싱크인의 양상을 파악하고 그 양을 정량화하기 위하여 가공경화양에 따른 표면변화와 압입하중 변화에 따른 표면변화를 관찰하였다. 어닐링한 봉상 알루미늄을 압축변형을 0%, 5%, 20%, 40%, 50% 로 변형시켜 가공경화를 일으켰고, 표면은 전해연마하여 나노압입시험이 가능하도록 하였다. 각각의 시편을 나노인덴테이션 압입하중을 변화시켜 재료에서 하중 변화에 따라 나타나는 표면변화를 관찰하였고, 위의 각 조건에서 파일업양을 정량화 하였다. 연구결과에 대해 ANSYS 유한요소분석 프로그램을 사용하여 재료의 변형양상을 시뮬레이션 하였고, 실제 실험데이터와 비교 분석하였다.

  • PDF

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
    • /
    • v.26 no.4
    • /
    • pp.95-100
    • /
    • 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.

Assessment of Yield Characteristics of Gas Pipeline Materials by Observing Surface-Local Deformation (미소 표면변형 관찰을 통한 가스배관 부재의 항복특성 평가)

  • Lee, Yun-Hee;Baek, Un-Bong;Cheong, In-Hyeon;Nahm, Seung-Hoon;Lee, Sang-Houck
    • Journal of the Korean Institute of Gas
    • /
    • v.12 no.2
    • /
    • pp.92-98
    • /
    • 2008
  • A combination of the instrumented indentation and 3D morphology measurement has been tried in order to perform a real-time property measurement of degraded materials in gas pipelines; three-dimensional indent morphologies were recorded using a reflective laser scanner after a series of insturmented indentations on three metallic specimens. Dimensions of the permanent deformation zone and contact boundary were analyzed from the cross-sectional profile over an remnant indent and used for estimating yield strength and hardness, respectively. Estimated yield strength was comparable with that from uniaxial tensile test and actual hardness implying material pile-up effects was lower than the calculated value from indentation curve by $20{\sim}30%$. It means that this 3D image analysis can explain the material pile-up effects on the contact properties. Additionally, a combined system of indentation and laser sensor was newly designed by modifying a shape of the indentation loading fixture.

  • PDF

Application of Continuous Indentation Technique for Reliability Evaluation in Power Plant Facilities (발전설비 주요배관 신뢰도 확보를 위한 연속압입시험 적용)

  • Park, Sang-Ki;Ahn, Yeon-Shik;Jung, Gye-Jo;Cho, Yong-Sang;Choi, Yeol
    • Journal of the Korean Society for Nondestructive Testing
    • /
    • v.24 no.2
    • /
    • pp.158-162
    • /
    • 2004
  • Reliability of welded structures in power plant facilities is very important, and their reliability evaluation requires exact materials properties. But, the conventional PQR (Procedure Qualification Record) can hardly reflect the real material properties in the field because the test is only done on specimens with simulated welding. Therefore, a continuous indentation technique is proposed in this study for simple and non-destructive testing of in-field structures. This test measures the indentation load-depth curve during indentation and analyzes the mechanical properties such as the yield strength, tensile strength and work hardening index. This technique has been applied to evaluate the tensile properties of the weldment in the main steam pipe and hot reheater pipe in power plants under construction and in operation.

Correction of the hardness measurement for pile-up materials with a nano indentation machine (파일-업 재료에 대한 나노 압입 시험기의 경도 측정값 교정)

  • Park, Moon Shik
    • Journal of the Korea Academia-Industrial cooperation Society
    • /
    • v.17 no.12
    • /
    • pp.98-106
    • /
    • 2016
  • Measurements of the elastic modulus and hardness using a nano indentation machine rely on the equation for the fitted contact area, which is valid for only sink-in materials. For most soft engineering materials that involve pile-up behavior rather than sink-in, the contact area equation underestimates the contact area and thus overestimates the elastic modulus and hardness. This study proposes a correction method to amend erroneous hardness measurements in pile-up situations. The method is a supplemental derivation to the original hardness measurement with the known value of the elastic modulus. The method was examined for soft engineering metals, Al 6061 T6 and C 12200, via tensile tests, nano indentation tests, impression observations, and finite element analysis. The proposed technique shows reasonable agreement with the analytical results accounting for strain gradient plasticity from a previous study.

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.

Evaluation of Indentation Fracture Toughens in Brittle Materials Based on FEA Solutions (유한요소해에 기초한 취성재료의 압입파괴인성평가)

  • Hyun, Hong Chul;Lee, Jin Heang;Felix, Rickhey;Lee, Hyungyil
    • Transactions of the Korean Society of Mechanical Engineers A
    • /
    • v.37 no.12
    • /
    • pp.1503-1512
    • /
    • 2013
  • In this study, we proposed an indentation evaluation method for fracture toughness using cohesive finite element simulations. First, we examined the effect of material properties (yield strain, Poisson's ratio, and elastic modulus) on crack size during Vickers indentation and then generated a regression formula that explains the relations among fracture toughness, indentation load, and crack size. We also proposed another indentation formula for fracture toughness evaluation using the contact size a and E/H (H: hardness). Finally, we examined the relation between the crack size and the indenter shapes. Based on this, we can generate from the formula obtained using the Vickers indenter a formula for an indenter of different shapes. Using the proposed method, fracture toughness is directly estimated from indentation data.

A Study on Evaluation of Rock Brittleness Index using Punch Penetration Test (압입시험을 이용한 암석의 취성도 평가에 관한 연구)

  • Hoyoung Jeong
    • Tunnel and Underground Space
    • /
    • v.33 no.1
    • /
    • pp.29-41
    • /
    • 2023
  • The brittleness of rocks plays an important role in determining the fragmentation and failure behavior of rock. However, there is still no standard method to evaluate the brittleness of rock, and previous studies have suggested the several definitions for estimation of brittleness of rock. Even in the process of mechanical rock excavation and drilling, the brittleness of rock is considered as an important property for evaluating the excavation efficiency of mechanical excavators or boreability of rock. The previous studies have been carried out to investigate the correlation between different brittleness of rock and cutting efficiency and boreability of rock. This study introduced a method for calculating the brittleness of rock from punch penetration test, and analyzed the correlation between the brittleness of rock calculated by the uniaxial compressive and Brazilian tensile strengths and that from punch penetration test. From the results of correlation analysis, the relationship between various brittleness was confirmed, and it was found that PSI and BI3 showed a good correlation with the strength-based brittleness index. In addition, the results indicated that B3 and B4 are suitable to represent the brittleness of rock in the field of mechanical rock excavation.