• Title/Summary/Keyword: 홉킨스바

Search Result 5, Processing Time 0.021 seconds

Rock Fragmentation Assessment of a Drill Bit by Hopkinson Bar Percussion Test (홉킨스바 타격시험을 통한 드릴비트의 암반파쇄 분석)

  • Kwon, Ki-Beom;Song, Chang-Heon;Park, Jin-Young;Shin, Dae-Young;Cho, Jung-Woo;Cho, Sang-Ho
    • Tunnel and Underground Space
    • /
    • v.23 no.1
    • /
    • pp.42-53
    • /
    • 2013
  • The percussion rate and spacing of the button of drill bit are very important in maximizing the drilling efficiency. Therefore, a series of percussion tests using Hopkinson bar system was carried out to assess the fragmentation performance against the beat rate and spacing of a drill bit. First, single percussion test complemented with numerical simulation was performed to analyze rock fragmentation phenomenon and to describe the fragmentation process. Next, multiple percussion test that repetitively strike the rock sample moving at predetermined rate was carried out to predict drilling efficiency against the button spacing. After the tests, the fragmented volume of the rock was measured by laser scanner and the drilling performance was analyzed using the calculated percussive energy and measured negative volume. Based on the results, the single impact performance of drill bit with 102 mm diameter was predicted.

Design and Fabrication of Split Hopkinson Pressure Bar for Dynamic Mechanical Properties of Self-reinforced Polypropylene Composite (폴리프로필렌 자기 보강 복합재의 동적 물성 구축을 위한 Split Hopkinson Pressure Bar의 설계 및 제작)

  • Kang, So-Young;Kim, Do-Hyoung;Kim, Dong-Hyun;Kim, Hak-Sung
    • Composites Research
    • /
    • v.31 no.5
    • /
    • pp.221-226
    • /
    • 2018
  • The Split Hopkinson Pressure Bar(SHPB) has been the most widely used apparatus to characterize dynamic mechanical behavior of materials at high strain rates between $100s^{-1}$ and $10,000s^{-1}$. The SHPB test is based on the wave propagation theory which was developed to give the stress, strain and strain rate in the specimen using the strains measured in the incident and transmission bars. In this study, the SHPB was directly designed and fabricated for the dynamic mechanical properties of fiber reinforced plastic (FRP) composites. In addition, this apparatus was verified for the validity by comparing the strain data obtained through the high speed camera and Digital Image Correlation(DIC) during the high strain rate compression test of the self-reinforced polypropylene composite (SRPP) specimen.

Effect of the density of PolyPropylene foams on the absorption of the impact energy (충격에너지 흡수에 미치는 폴리프로필렌 폼 밀도의 영향)

  • 박남훈;고영호;문기석;윤희석
    • Proceedings of the Korean Society of Precision Engineering Conference
    • /
    • 2003.06a
    • /
    • pp.1398-1401
    • /
    • 2003
  • Recently, The PolyPropylene(PP) Foam used as Bumper and Helmet is well known as a protective material for products. In this paper, the effect of the density of PP foams on the absorption of the impact energy is implemented. The result of the experiment has revealed that the effect of the high-density PP foams is remarkably increased compared with that of the low-density PP foams. And it also shows that the absorption of the impact energy of PP foams are greatly influenced by the density in impact velocity(220cm/s). These results are expected to be utilized for the technique of manufacturing a optimum impact structure.

  • PDF

A Numerical Study on the Dynamic Characteristics of Power Metal using Split Hopkinson Pressure Bar (홉킨스바 장치를 이용한 분말금속의 동적 특성에 관한 수치해석적 연구)

  • Hwang, Du-Sun;Lee, Seung-U;Hong, Seong-In
    • Transactions of the Korean Society of Mechanical Engineers A
    • /
    • v.24 no.12
    • /
    • pp.2972-2979
    • /
    • 2000
  • Dynamic characteristics of powder metal is very important to mechanical structures requiring high strength or endurance for impact loading. But owing to distinctive property of powder metal, that is relative, it has been investigated restrictively compared to static characteristics. The objectives of this study is to investigate dynamic characteristics of powder metal and compare it to a fully density material. To find the characteristics, an explicit finite element method is used for simulation of Split Hopkinson Pressure Bar experiment based on the stress wave propagation theory. We obtained a dynamic stress-strain relationship and dynamic behavior of powder metal, as well as the variation of material properties during dynamic deformation.

Study on the Split Hopkinson Pressure Bar Apparatus for Measuring High-strain Rate Tensile Properties of Plastic Material (플라스틱 소재의 고 변형률 인장특성 평가를 위한 홉킨스바(Split Hopkinson Pressure Bar) 측정 장비에 관한 연구)

  • Han, In-Soo;Lee, Se-Min;Kim, Kyu-Won;Kim, Hak-Sung
    • Composites Research
    • /
    • v.35 no.3
    • /
    • pp.196-200
    • /
    • 2022
  • Split Hopkinson Pressure Bar (SHPB) is a general test equipment for measuring the mechanical properties of high modulus metal and composite materials at high strain rate. However, for the soft plastic material, it is difficult to hold the specimen and achieve dynamic stress equilibrium due to the weak transmitted signals. In this study, SHPB test apparatus were designed to measure accurately the high strain rate stress-strain curve of the soft plastic materials by changing the incident bar materials and the shape of the specimen holder parts. In addition, to verify the high strain-rate tensile strain data obtained from SHPB, the strain distribution of the specimen was measured and analyzed with a high-speed camera and the digital image correlation (DIC), which was compared with the strain history measured from SHPB.