• 제목/요약/키워드: residual rate

검색결과 1,524건 처리시간 0.026초

SUS-304강 용접부의 잔류응력이 피로균열진전속도에 미치는 영향 (Effect of Residual Stress on Fatigue Crack Growth Rate at Welds of SUS-304 Steel)

  • 이택순;양현태
    • Journal of Welding and Joining
    • /
    • 제15권4호
    • /
    • pp.187-193
    • /
    • 1997
  • In the weldmentsm the crack propagation rate is changed due to the residual stress. The crack propagation rate is high in the region with the residual stress. However it shows rhw same behavior with the base metal in the region that does not include the residual stress. The fatigue crack growth rate for the material with residual stresses can be predicted more precisely by using the effective stress ratio. The difference between experimental results and prediction results in the initial stage seems to be due to the redistribution of residual stresses and microstructural change.

  • PDF

A Study on Trend Changes for Certain Parametric Families

  • Nam, Kyung Hyun;Park, Dong Ho
    • 품질경영학회지
    • /
    • 제23권3호
    • /
    • pp.93-101
    • /
    • 1995
  • We present a brief survey concerning the relations between mean residual life and failure rate. Change points of mean residual life and failure rate are known to be different in general and we explore such situations in this paper. A few parametric models which show bathtub-shaped failure rate are examined in details, including the shape of its corresponding mean residual life function. We give some graphical comparisons of trend changes of mean residual life and failure rate for various choices of parameters for each parametric model.

  • PDF

스테인리스강 용접부의 잔류응력이 피로특성에 미치는 영향 (Effect of Residual Stress on Fatigue Characteristics at the Welds of Stainless Steel)

  • 권종완;양현태
    • 한국공작기계학회논문집
    • /
    • 제10권5호
    • /
    • pp.110-117
    • /
    • 2001
  • In the weldments, the crack propagation rate is changed due to the residual stress. The crack propagation rate is high in the region with the residual stress. However it shows the same behavior with the base metal in the region that does not include the residual stress. The fatigue crack growth rate for the material with residual stresses can be predicted more precisely by using the effective stress ratio. The difference between experimental results and prediction results seems to be due to the redistribution of the residual stresses and microstructural change.

  • PDF

역세척수 회수시스템이 포함된 배출수처리공정의 설계 (Design of Residual Treatment Process with Filter Backwash Recycle System)

  • 배병욱;최경환
    • 한국물환경학회지
    • /
    • 제28권1호
    • /
    • pp.109-114
    • /
    • 2012
  • In this study, both sedimentation and thickening experiments were conducted for residuals produced from an advanced water treatment plant for more accurate and practical design of residual treatment train. In order to design a backwashed residual sedimentation basin (SRSB) in the filter backwash water recycle system, two kinds of backwash waters, one from sand filter (SFBW) and the other from GAC adsorption bed (GACBW), were separately collected and their surface loading rate measured. In addition, in order to design a gravity thickener, batch thickening tests were conducted for concentrated residuals taken from sedimentation basin and their limiting solid flux ($SF_{L}$) measured. From the experimental results and consideration of the seasonal characteristics of the residual, surface loading rate of $70m^{3}/m^{2}{\cdot}d$ was proposed as a design parameter for SRSB and solid loading rate of 20 kg $TS/m^{2}{\cdot}d$ was proposed as a design parameter for gravity thickeners. Finally, the material mass-balance was made for the design of each unit process in the residual treatment train.

피로균열이 진전할 때 용접잔류응력의 재분포와 그 영향 (Redistribution of Welding Residual Stress and its Effects on Fatigue Crack Propagation)

  • 이용복;조남익
    • Journal of Welding and Joining
    • /
    • 제13권4호
    • /
    • pp.155-162
    • /
    • 1995
  • Redistribution of residual stress and its effects during fatigue crack propagates from tensile residual stress region in weldment are investigated. Tests are performed by using welded CCT specimens of structual rolling steel (SS400) and it makes fatigue crack propagate from tensile residual stress region. For this study tension-tension loading type is selected by external loading condition and magnetizing stress indicator is used correctly to measure redistribution of residual stress according to fatigue crack growth and number of loading cycles. From this result, it is proved that redistribution of residual stress is mainly consist of residual stress released by fatigue crack growth. When fatigue crack propagates from tensile residual stress region residual stress are redistributed and it makes fatigue crack growth rate largely increase. Fatigue crack growth rate is low in case of redistributed residual stress compare with initial distributed residual stress.

  • PDF

Vickeres Indentation법에 의한 페라이트와 접합유리에서의 응력해석 (Interpretation of Stresses in the Glass Bonded Ferrites by Vickeres Indentation Method)

  • 안정환;제해준;홍국선;안재환;고경현
    • 한국세라믹학회지
    • /
    • 제30권6호
    • /
    • pp.469-477
    • /
    • 1993
  • Residual stresses is one of the major factors to degrade the magnetic properties of VCR magnetic heads. Vicker's indentation technique was adapted to estimate the residual stresses Residual stresses and distribution in the glass and ferrite were obtained after bonding ferrite with glass, varing the cooling rate. The compressive and tensile stresses were developed in the interface and gradually decreased with increasing distance from the interface. The stresses were decreased with a cooling rate. The mean values of residual stress in ferrite were 10MN/㎡, 8MN/㎡, 5MN/㎡ with cooling rate 10℃/min, 5℃/min, 1℃/min respectively. When the bonded sample was annealed above the glass transition temperature followed by cooling at 5℃/min cooling rate, the residual stress was reduced to 6MN/㎡.

  • PDF

다중충돌 쇼트피닝에서 변형률 속도와 소재 경도가 잔류응력에 미치는 영향에 관한 연구 (Effect of Strain Rate and Material Hardness on Residual Stress in Multiple Impact Shot Peening)

  • 김태우;양조예;나두현;이영석
    • 대한기계학회논문집A
    • /
    • 제35권11호
    • /
    • pp.1369-1375
    • /
    • 2011
  • 쇼트피닝 공정은 쇼트볼이 소재에 충돌을 일으킬 때 생기는 압축잔류응력에 의해 소재의 피로 강도를 향상 시키는데 그 목적이 있다. 본 연구는 변형률 속도 민감도 변화가 압축잔류응력에 미치는 영향을 분석하기 위해서 수행되었다. 본 연구자는 변형률 속도 민감도의 영향을 고려한 쇼트피닝 다중 충돌을 ABAQUS 6.9-1 를 사용하여 모사하였다. 사용된 소재는 AISI 4340 강종이다. 본 연구자는 변형률 속도 민감성이 높은 재료와 낮은 재료를 비교하였다. 결과적으로 변형률 속도 민감성이 증가하면 압축 잔류응력은 감소하였다. 또한 경도가 낮은 소재의 압축잔류응력이 경도가 높은 소재보다 더 크게 발생 하였다.

당근과 케일에서 저장온도와 양념첨가에 의한 잔류 Captan의 제거효과 (Removal of Residual Captan in Carrot and Kale by Storage Temperatures and Addition of Condiments)

  • 김성준;구평태;이병규;박건영
    • 한국식품위생안전성학회지
    • /
    • 제11권1호
    • /
    • pp.11-16
    • /
    • 1996
  • The removal of residual captan in carrot and by storage temperatures and the addition of condiments was investigates. The quantities of residual captan after sticking and drying of captan in carrot and kale wer 0.958 and 23.12 ppm, respectively. During storage of 20days at 15,3 and -17$^{\circ}C$, the levels of the residual captan in carrot decreased to 0.008 (removal rate: 99.2%) and 15.06 ppm (42.3%), respectively. The higher removal rate of residual captan was oberved at the higher storage temperatures, When the condiments of soy sauce, green onion, garlic and vinegar added to the carrot which contaminated with the captan and then stored at 15$^{\circ}C$ for 24hrs, the residual levels of captan decreased to 0.207 (removal rate: 78.4%), 0.196 (79.5$^{\circ}C$), 0.164 (82.8$^{\circ}C$) and 0.209 ppm (78.2%), respectively, showing the garlic was the most effective. However, the residual levels in tale were 2.27 (91.3%), 12.70 (51.4%), 16.42 (37.1%) and 13.70 ppm (47.5%), respectively under the same condition, indication the soy sauce was the most effective. The removal rates of residual captan in carrot and kale were significantly higher with the addition of the condiments than those of the controls that without the condiments.

  • PDF

가압부상 후 잔류 응집제가 플랑크톤 군집에 미치는 영향 (The Effects of Residual Al on Plankton Community after Dissolved Air Flotation (DAF) Application)

  • 김호섭;공동수;이형진;신종규;강태구
    • 한국물환경학회지
    • /
    • 제23권6호
    • /
    • pp.837-842
    • /
    • 2007
  • This study was conducted to test the effect of residual Al on plankton community after dissolved air flotation (DAF) application. Growth rate of phytoplankton after DAF application ($0.37day^{-1}$) was about 2 times lower than that before DAF application ($0.70day^{-1}$). Under the condition of addition of nitrogen and phosphorus without light, growth rate phytoplankton in treatment without residual Al increased in difference with showing the negative growth rate in treatment with residual Al. Under the condition of light without addition of nutrient, growth rate of phytoplankton was no noticeable difference between the before and after DAF application. The relatively high settling rate (0.47 m/day) was observed in treatment after DAF application. Although the abundance of rotifer decreased, the abundance of copepod and cladoceran such as Daphnia galeata, Diaphanosoma sp. and Bosmina longirostris with relative higher grazing was no noticeable difference between the before and after DAF application. In the treatments before and after DAF application with zooplankton, growth rate of phytoplankton was $0.41{\pm}0.08day^{-1}$, $0.20{\pm}0.03day^{-1}$, respectively. This difference was in treatment after DAF application similar with those in treatments before and after DAF application without zooplankton. Those indicate that the filter-feeding effect of zooplankton on phytoplankton community may be not changed by residual Al after the DAF application. These results suggest that residual Al after DAF application be to improve water quality by inhibition of growth rate as well as increasing settling rate of phytoplankton.

상수관로의 잔존수명 평가를 위한 통계적 방법론 (A Statistical Methodology for Evaluating the Residual Life of Water Mains)

  • 박수완;최창록;김정현;배철호
    • 상하수도학회지
    • /
    • 제23권3호
    • /
    • pp.305-313
    • /
    • 2009
  • This paper provides a method for evaluating a residual life of water mains using a proportional hazard model(PHM). The survival time of individual pipe is defined as the elapsed time since installation until a break rate of individual pipe exceeds the Threshold Break Rate. A break rate of an individual pipe is estimated by using the General Pipe Break Model(GPBM). In order to use the GPBM effectively, improvement of the GPBM is presented in this paper by utilizing additional break data that is the cumulative number of pipe break of 0 for the time of installation and adjusting a value of weighting factor(WF). The residual lives and hazard ratios of the case study pipes of which the cumulative number of pipe breaks is more than one is estimated by using the estimated survival function. It is found that the average residual lives of the steel and cast iron pipes are about 25.1 and 21 years, respectively. The hazard rate of the cast iron pipes is found to be higher than the steel pipes until 20 years since installation. However, the hazard rate of the cast iron pipes become lower than the hazard rates of the steel pipes after 20 years since installation.