• Title, Summary, Keyword: Loading rate

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Effect of Loading Rate on the Fracture Behavior of Nuclear Piping Materials Under Cyclic Loading Conditions

  • Kim, Jin Weon;Choi, Myung Rak;Kim, Yun Jae
    • Nuclear Engineering and Technology
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    • v.48 no.6
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    • pp.1376-1386
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    • 2016
  • This study investigated the loading rate effect on the fracture resistance under cyclic loading conditions to understand clearly the fracture behavior of piping materials under seismic conditions. J-R fracture toughness tests were conducted under monotonic and cyclic loading conditions at various displacement rates at room temperature and the operating temperature of nuclear power plants (i.e., $316^{\circ}C$). SA508 Gr.1a low-alloy steel and SA312 TP316 stainless steel piping materials were used for the tests. The fracture resistance under a reversible cyclic load was considerably lower than that under monotonic load regardless of test temperature, material, and loading rate. Under both cyclic and monotonic loading conditions, the fracture behavior of SA312 TP316 stainless steel was independent of the loading rate at both room temperature and $316^{\circ}C$. For SA508 Gr.1a lowalloy steel, the loading rate effect on the fracture behavior was appreciable at $316^{\circ}C$ under cyclic and monotonic loading conditions. However, the loading rate effect diminished when the cyclic load ratio of the load (R) was -1. Thus, it was recognized that the fracture behavior of piping materials, including seismic loading characteristics, can be evaluated when tested under a cyclic load of R = -1 at a quasistatic loading rate.

Performance of Rotating Biological Contactor (RBC) under Different Hydraulic Loading Rates and Rotational Speeds on Ammonia Removal in a Recirculating System

  • Son Maeng Hyun;Jeon Im Gi;Jo Jae-Yoon;Moon HaeYoung
    • Fisheries and aquatic sciences
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    • v.2 no.1
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    • pp.52-57
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    • 1999
  • Air-drived rotating biological contactor (RBC) system, which is effective method in filtering performance, was tested for the nitrification capacity in a recirculating system. At ammonia concentrations between 0.029 and 0.528 mg/l, the effect of ammonia loading rate on ammonia removal rate at three different hydraulic loading rates could be defined by the following first­order regression models: Hydraulic loading rate of $14.8 m^3/m^3/day:\;y=39.2\times+3.4 (r^2=0.9137)$, Hydraulic loading rate of $26.5 m^3/m^3/day: y=53.3\times+4.0 (r^2=0.8686)$, Hydraulic loading rate of $37.3 m^3/m^3/day: y=58.4\times+4.2 (r^2=0.7755)$, where, $\times$ is ammonia loading rate (mg/l), y is ammonia removal rate $(g/m^3/day)$, The equations showed the optimal ammonia removal rate at the hydraulic loading rate of $26.5m^3/m^3/day$. Below the ammonia concentration of 2.72 mg/l, first-order regression models between ammonia loading rate and ammonia removal rate at three different rates of speed are defined as follows: Rotational speed of $0.75 rpm: y=28.5\times+4.7 (r^2=0.9143)$, Rotational speed of $1.0 rpm: y=33.6\times+8.4 (r^2=0.9534)$, Rotational speed of $2.0 rpm: y=28.9\times+3.6 (r^2=0.9488)$, where, x is ammonia loading rate (mg/l), y is ammonia removal rate $(g/m^3day)$. The equations show the ammonia removal rate at the rotational speed of 1.0 rpm is significantly higher than that at the rotational speed of either 0.75 rpm or 2.0 rpm (P<0.05).

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Loading rate effect on the delamination toughness of carbon/epoxy composites (하중속도가 탄소섬유/에폭시 적층복합재의 층간분리인성에 미치는 영향)

  • Ha S.R.;Rhee K.Y.;Kim H.J.;Jung D.H.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.593-597
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    • 2005
  • It is generally accepted that fracture toughness of fiber-reinforced polymer composites is affected by loading rate in an atmospheric presure condition. For a present study, the loading rate effect on the fracture toughness of fiber-reinforced laminated composites in the hydrostatic pressure condition was investigated. For this purpose, fracture tests have been conducted using carbon/epoxy composites applying three steps of the strain rate at 270 MPa hydrostatic pressure condition. The loading rates applied were 0.05%/sec, 0.25%/sec, and 0.55%/sec. Fracture toughness was determined from the work factor approach as a function of applied loading rate. The result showed that fracture toughness decreased as the loading rate increased. Specifically, the fracture toughness decreased 12% as the loading rate increased from 0.05%/sec to 0.55%/sec.

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Determination of Deformation Behavior of the Al6060-T6 under high Strain Rate Tensile Loading Using SHPB Technique (SHPB 기법을 이용한 A16061-T6의 고속 인장 변형거동 규명)

  • Lee, Eok-Seop;Kim, Gwan-Hui;Hwang, Si-Won
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.24 no.12
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    • pp.3033-3039
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    • 2000
  • Mechanical properties of the materials used for transportations and industrial machinery under high stain rate loading conditions have been required to provide appropriate safety assessment to these mechanical structures. The Split Hopkinson Pressure Bar(SHPB) technique with a special experimental apparatus can be used to obtain the material properties under high strain rate loading condition. There have been many studies on the material behavior under high strain rate compressive loading compared to those under tensile loading. In this paper, mechanical properties of the aluminum alloy, Al6061-T6, under high strain rate tensile loading were determined using SHPB technique.

Treatment of Organic Wastewater by the Anaerobic Fixed-Film Process (혐기성 생물막법에 의한 유기성 배수의 처리)

  • 김용대;정경훈
    • Journal of Environmental Health Sciences
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    • v.17 no.2
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    • pp.41-47
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    • 1991
  • A study on the effects of volumetric loading rate, surface loading rate and hydraulic. retention time (HRT) for the anaerobic treatment was conducted with the anaerobic fixed-film process using synthetic wastewater at lower temperature than that of conventional anaerobic treatment. The results are as follows 1. Alkalinity and pH value decreased as the hydraulic retention time increased 2. Increase of the volumetric lodaing rate led to increasl of effluent COD concentration and decrease of COD removal efficiency. 3. The removed volumetric loading rate increased linearly according to the increase of the volumrtric loading rate. 4. Similarly, the linear increase of the removed surface loading rate was noticed with an increase of the surface loading rate.

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Effect of Loading Rate on Acidogenic Fermentation of Domestic Waste Sludge (산발효에 있어서 하수슬러지의 유입부하율의 영향)

  • Eom, Tae-Kyu;Han, Dong-Yueb
    • Journal of Korean Society of Water and Wastewater
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    • v.18 no.1
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    • pp.15-21
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    • 2004
  • The purpose of this research was to investigate loading rate of influent for acidogenic fermentation. Laboratory batch experiments were conducted, at $35^{\circ}C$, HRT 18hr, pH 6 and used 3.5L reactor. Loading rate of influent was varied 2.0 to 4.0g VSS/L, TOA concentration is decreased according to increasing loading rate Over 2.5g VSS/L. When loading rate is 2.0g VSS/L, hydrolysis percentage show the maximum value of 87%. Most of SCFA is consist of HAc, HPr, I-HBu and MBu. HAc concentration is 5,233mg/L in the 2.0g VSS/L condition. So, for this study, we think that limiting loading rate is 2.5g VSS/L. SCFA species was investigated to HAc, HPr, I-HBu and n-HBu during our studying. HAc/SCFA ratio is about 89.3%, SCFA production rate is highest to $1,104mg\;COD/L/d{\cdot}gPCOD$ for 2.0g VSS/L loading rate.

Fracture Strength Measurement of Single Crystal Silicon Chips as a Function of Loading Rate during 3-Point Bending Test (3점 굴곡 실험에서 하중 속도 변화에 따른 단결정 실리콘 칩의 파괴강도 측정)

  • Lee, Dong-Ki;Lee, Seong-Min
    • Korean Journal of Metals and Materials
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    • v.50 no.2
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    • pp.146-151
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    • 2012
  • The present article shows how the fracture strength of single crystal silicon chips, which are generally used as semiconductor devices, is influenced by loading rate variation during a 3-point bending test. It was found that the fracture strength of the silicon chips slightly increases up to 4% with increasing loading rate for loading rates lower than 20 mm/min. Meanwhile, the fracture strength of the chips hardly increases with increase of loading rate to levels higher than 40 mm/min. However, there was an abrupt transition in the fracture strength within a loading rate range of 20 mm/min to 40 mm/min. This work explains through microscopic examination of the fracture surface of all test chips that such a big transition is related to the deflection of crack propagation direction from the (011) [${\bar{1}}00$] system to the (111) [${\bar{2}}11$] system in a particular loading rate (i.e. from 20 mm/min to 40 mm/min).

Anaerobic Degradation of Inhibitory Organics using Fluidized Bed Reactor -Increase of Phenol Loading Rate- (유동층 반응기를 이용한 저해성 유기물의 혐기성 분해 -페놀 부하 증가 중심으로-)

  • 박동일;최석규;김재우
    • Journal of Environmental Health Sciences
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    • v.24 no.2
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    • pp.57-67
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    • 1998
  • The characteristics of anaerobic degradation of phenol were studied in a fluidized bed reactor using a granular activated carbon as media. Increasing the phenol loading rate with variation of feed concentration was considered as an experimental variable. In the present anaerobic fluidized-bed reactor, the removal efficiency of phenol and COD was maintained about 93-99% and 91-96%, respectively, up to 3.6 kg-phenol/$m^3\cdot d$ of the phenol loading rate, but it was abruptly decreased under 5.0 kg-phenol/$m^3\cdot d$. The volumetric production of biogas per removed phenol was decreased linearly between 0.80-1.27 m$^3$ gas/kg-phenol (0.35-0.56 m$^3$-gas/kg-COD), increasing the phenol loading rate, and the methane content of biogas was 55-60% as similar to that estimated theoretically up to 3.6 kg-phenol/$m^3\cdot d$. But the production rate and methane content of biogas were suddenly decreased at the loading rate of 5.0 kg-phenol/$m^3\cdot d$. Therefore, the anaerobically biodegradable phenol loading rate of the present reactor was 3.6 kg-phenol/$m^3\cdot$ d in order to accomplish over 90% of the removal efficiency.

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Stress-Strain Behaviour of Overconsolidated Clay with Loading Rate (하중재하속도에 따른 과압밀점토의 응력-변형 거동)

  • 김병일;신현영;이승원;김수삼
    • Proceedings of the Korean Geotechical Society Conference
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    • pp.239-244
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    • 2001
  • Natural clayey soils or improved grounds are in a overconsolidated conditions due to changes in vertical stress and pore pressures, desiccation, ageing and so on. These grounds show inelastic stress-strain behaviour characteristics within all range of strain except very small strain (${\gamma}$$\_$s/$\leq$10 ̄$^3$∼10 ̄$^4$%) when construction, such as excavations and retaining walls, is performed. Also it strongly depends on loading rate of current stress path and recent stress path. This study carried out drained stress path tests by varying loading rate of current and recent stress path. Test results indicated that stress-strain behaviour of overconsolidated clay depends on loading rate, especially loading rate of current stress path.

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Effect of loading rate on mechanical behavior of SRC shearwalls

  • Esaki, Fumiya;Ono, Masayuki
    • Steel and Composite Structures
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    • v.1 no.2
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    • pp.201-212
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    • 2001
  • In order to investigate the effect of the loading rate on the mechanical behavior of SRC shearwalls, we conducted the lateral loading tests on the 1/3 scale model shearwalls whose edge columns were reinforced by H-shaped steel. The specimens were subjected to the reversed cyclic lateral load under a variable axial load. The two types of loading rate, 0.01 cm/sec for the static loading and 1 cm/sec for the dynamic loading were adopted. The failure mode in all specimens was the sliding shear of the in-filled wall panel. The edge columns did not fail in shear. The initial lateral stiffness and lateral load carrying capacity of the shearwalls subjected to the dynamic loading were about 10% larger than those subjected to the static loading. The effects of the arrangement of the H-shaped steel on the lateral load carrying capacity and the lateral load-displacement hysteresis response were not significant.