• 제목/요약/키워드: fatigue behaviors

검색결과 298건 처리시간 0.021초

J파라미터를 이용한 고온피로균열전파 거동에 미치는 응력파형 영향의 연구 (A Study of the Effect of Stress Waveform on the Behavior of High Temp. Fatigue Crack Propagation Using J Parameters)

  • 허정원;박원조
    • 한국안전학회지
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    • 제15권2호
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    • pp.8-12
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    • 2000
  • The fatigue crack propagation tests were performed in triangular and holding-time stress waveforms at $650^{\circ}C$. The behavior of fatigue crack propagation was investigated according to waveform. The analysis of high temperature fatigue crack propagation by the stress intensity factor range ${\Delta}K$, elastic fracture mechanics parameter, was not available. The behaviors of high temperature fatigue crack propagation by the J-integral(${\Delta}J_f$, J' and ${\Delta}J_c$), elasto-plastic fracture mechanics parameter, were investigated in a number of stress waveforms. The fast-fast waveform exhibited cycle-dependent(fatigue type), the slow-fast and the hold time with 500sec waveforms appear to be time-dependent(creep type) and the fast-slow and the hold time with 5, 25sec waveforms exhibited conbined behavior of both types(fatigue-creep conbined type).

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원전 안전 3등급 고밀도 폴리에틸렌 매설 배관 맞대기 열 융착부의 굽힘 피로특성 평가 (Investigation of Bending Fatigue Behaviors of Thermal Butt Fusion in Safety Class III High-Density Polyethylene Buried Piping in Nuclear Power Plants)

  • 김종성;이영주;오영진
    • 한국압력기기공학회 논문집
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    • 제11권2호
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    • pp.40-44
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    • 2015
  • The fatigue behavior of thermal butt fusion in safety class III high-density polyethylene (HDPE) buried piping for nuclear power plants was investigated using load-controlled bending fatigue on four-point bend test specimens. Based on the results, the presence of thermal butt fusion beads was confirmed to reduce the fatigue lifetime in the low- and medium-cycle fatigue regions while having a negligible effect in the high-cycle fatigue regions.

단일과대하중하의 부식피로균열진전거동에 관한 연구 (A Study on Corrosion Fatigye Crack Propagation Behaviors due to a Single Overload)

  • 강동명;이하성;우창기
    • 한국정밀공학회:학술대회논문집
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    • 한국정밀공학회 1997년도 춘계학술대회 논문집
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    • pp.481-485
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    • 1997
  • 6063-T5 alloys are tested in laboratory air, water and 3% NaCl solution to investigate the effects of corrosive environment on the retardation behavior through single overload fatigue test. Also, the fatigue crack propagation and the crack closure behavior are studied. The results obtained in this experimental study are summarized as follows: 1) Behaviors of fatigue crack growth retardation are observed in water and 3% NaCl solution as they do in air. The number of delay cycles and the size of affected region by single overload decrease greatly in water and 3% NaCl compared with those in air. 2) In fractographic results, the overload marking by single overload appear remarkably in air, but indistinctly in water and 3% NaCl solution. 3) The effect of crack closure on crack propagation is most remarkable in the beginning of crack propagation. With crack propagation, the crack closure level and its effect decrease greatly.

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1.5Cr-0.67Mo-0.33V강의 열피로 크랙전파 거동 (Thermo-Mechanical Fatigue Crack Propagation Behaviors of 1.5Cr-0.67Mo-0.33V Alloy)

  • 송삼홍;강명수
    • 대한기계학회논문집
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    • 제19권9호
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    • pp.2133-2141
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    • 1995
  • The thermo-mechanical fatigue tests were performed on the specimens extracted from 1.5Cr-0. 67Mo-0.33V alloy. The characteristics of thermo-mechanical fatigue crack propagation were examined and reviewed in view of fracture mechanics. The results obtained from the present study are summarized as follows : (1) The propagation characteristics of isothermal low-cycle fatigue crack are dominated by .DELTA.J$_{f}$ in case of PP waveform, and .DELTA.J$_{c}$ in case of CP waveform. (II)The propagation characteristics of thermo-mechanical fatigue crack are dominated by .DELTA.J$_{c}$ for in-phase case, and by .DELTA.J$_{c}$ for out-of-phase. The present results were in good agreement with the equation of propagation law for isothermal low-cycle fatigue crack in case of thermo-mechanical fatigue.tigue.e.

산업피로의 발생과 대책에 관한 연구 (The Studies on the Occurrence & Countermeasures of Industrial Fatigue)

  • 신현재;안병준
    • 산업경영시스템학회지
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    • 제6권8호
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    • pp.41-48
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    • 1983
  • On the studies of the occurrence & countermeasures of industrial fatigue, the authors obtained the following results in the prevention & recovery of the industrial fatigue. Do not overtime work. To remove the unnecessary behaviors movement. To decide the standard amounts of work. Take a rest property in the procedures of work. Adjust & Arrange the work environments. Take a sufficient mutvition calories. Have plenty in reserve worktime. Set up modernizing machinery. To pay living wages.

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TMCP 고장력강 용접부의 부식도영 특성에 관한 연구 (A Study on Corrosion Fatigue Properties of Welded Joints for TMCP High Strength Steels)

  • 이택순;이휘원;김영철
    • 한국해양공학회지
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    • 제10권3호
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    • pp.14-23
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    • 1996
  • The corrosion fatigue test were carried out to evaluate the fatigue characteristics of accelerated cooled (ACC) TMCP high tensile strength steels and weld joint with high heat input by one side one run submerged are welding. In this paper, the fatigue crack growth behaviors were investigated with the center crack tension specimen of base metal and heat affected zone in substitute sea water and air, respectively Main results obtained are sunnarized as follows: 1. The fatigue crack growth rates in sea water faster than those in air environment for the different heat input values, crack growth rate of base metal is very fast and effect of heat input is not remarkable. 2. In HAZ (82kJ/cm, 116kJ/cm), the crack branching phenomena were observed in both air and sea water environment, 3. In SEM observation, the corrosion effect on base metal was larger than that on HAZ in corrosion environment.

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Fatigue characteristics of $Pb(Zr,Ti)O_3$ capacitors on donor doping

  • Yang, Bee Lyong
    • 열처리공학회지
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    • 제15권3호
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    • pp.113-117
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    • 2002
  • Fatigue characteristics of ferroelectric $Pb(Zr,Ti)O_3$ (PZT) based capacitors through donor doping is reported in this paper. La substitution up to 10% were carried out to study systematically the fatigue behaviors of epitaxial ferroelectric capacitors grown on Si using $(Ti_{0.9}Al_{0.1})N/Pt$ conducting barrier composite. Ferroelectric capacitors substituted with 10% La show sufficient low voltage switched polarization and fatigue free performance. Systematic decrease in the tetragonality of the ferroelectric phase (i.e., c/a ratio) results in the corresponding reduction in coercive voltage, sufficient remnant polarization at 1.5-3V, and good fatigue property.

Crack Opening Behavior of Perpetrated Crack Under Fatigue Load

  • Nam, Ki-Woo;Ahn, Seok-Hwan
    • Journal of Mechanical Science and Technology
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    • 제16권1호
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    • pp.24-31
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    • 2002
  • The leak-before-break (LBB) behaviors of a structural component under high and low fatigue loads are an important problem in nuclear power plants, liquid nitrogen gas tankers and chemical plants. This paper is an experimental study to evaluate the crack opening behavior after penetration for plate and pipe specimens. Crack opening displacement after penetration under low fatigue load could be satisfactorily determined at the center of the plate thickness regardless of the specimen size. In the case of high fatigue load, it is shown that the crack opening displacement at the center of a penetrated crack carl be derived using the gross stress, $\sigma$/sug G/, and the front surface crack length, a$\_$s/, together with the back surface crack length, a$\_$b/.

단섬유/입자 혼합 금속복합재료의 피로균열진전 거동 (Fatigue Crack Growth Behavior of Short fiber/Particle Hybrid Metal Matrix Composites)

  • 오광환;장준호;한경섭
    • 한국복합재료학회:학술대회논문집
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    • 한국복합재료학회 2004년도 춘계학술발표대회 논문집
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    • pp.219-222
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    • 2004
  • The effects of short fiber and particle hybrid reinforcement on fatigue crack propagation behaviors in aluminum matrix composites have been investigated. Single and hybrid reinforced 6061 aluminum containing same 20 $Al_2O_3\;volume\%$ with four different constituent ratios of short fibers and particles were prepared by squeeze casting method and tested to check the near-threshold and stable crack growth behavior. The fatigue threshold of the composites increased with portion of particle contents and showed the improved crack resistance especially in low stress intensity range. Addition of particle instead of short fiber also increased fracture toughness due to increase of inter-reinforcement distance. These increase in both fatigue threshold and fracture toughness eventually affected the fatigue crack growth behavior such that the crack growth curve shift low to high stress intensity factor value. Overall experimental results were shown that particle reinforcement was enhanced the fatigue crack resistance over the whole stress intensity factor range.

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불규칙하게 분포된 미소결함사이의 응력간섭 및 피로균열 거동에 대한 실험적 연구 (II) (결함간의 거리 및 하중변화를 중심으로) (An Experimental Study on the Fatigue Behavior and Stress Interaction of Arbitrarily Located Defects (II) (For Variable Loads and Distances between Defects))

  • 송삼홍;배준수;최병호
    • 한국정밀공학회지
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    • 제18권1호
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    • pp.201-212
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    • 2001
  • If defects are located far apart, fatigue cracks are independently initiated from them and gradually approach other cracks so that the fatigue life becomes influenced by the crack growth behavior of those interacting cracks. In this study, the effect of the stress interaction between defects on the fatigue crack propagation behavior is investigated experimentally and these results are verified by finite element method. In addition, fatigue crack propagation behaviors under micro hole interaction field are studied.

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