• Title/Summary/Keyword: Hoop stress

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An Improved Pipe Hoop Stress Formula

  • Lee, Jaeyoung
    • Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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    • 2001.05a
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    • pp.76-82
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    • 2001
  • The ASME B3l.4〔1〕and B3l.8 〔2〕codes use the thin wall formula to predict hoop stress in a pipe. To account for the external pressure, the above codes simply subtract the external pressure from the internal pressure. The thin wall formula using this differential pressure does not give the same hoop stress as the thick wall formula. This paper proposes an improved equation to predict pipe hoop stress subjected to both internal and external pressure. Compared to the conventional thin wall formula, the improved formula has additional terms, which improve the agreement with the thick wall formula and account for external pressure. The improved formula is less conservative than the conventional thin wall formula, but slightly more conservative than the thick wall formula. The formula is simpler and easier to use than the thick wall formula and will save pipe material cost as well as installation cost compared to using the conventional thin wall formula. The savings will increase as the water depth increases.

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FEA Study on Hoop Stress of Multilayered SiC Composite Tube for Nuclear Fuel Cladding (핵연료 피복관용 다중층 SiC 복합체 튜브의 Hoop Stress 전산모사 연구)

  • Lee, Hyeon-Geun;Kim, Daejong;Park, Ji Yeon;Kim, Weon-Ju
    • Journal of the Korean Ceramic Society
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    • v.51 no.5
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    • pp.435-441
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    • 2014
  • Silicon carbide-based ceramics and their composites have been studied for application to fusion and advanced fission energy systems. For fission reactors, $SiC_f$/SiC composites can be applied to core structural materials. Multilayered SiC composite fuel cladding, owing to its superior high temperature strength and low hydrogen generation under severe accident conditions, is a candidate for the replacement of zirconium alloy cladding. The SiC composite cladding has to retain its mechanical properties and original structure under the inner pressure caused by fission products; as such it can be applied as a cladding in fission reactor. A hoop strength test using an expandable polyurethane plug was designed in order to evaluate the mechanical properties of the fuel cladding. In this paper, a hoop strength test of the multilayered SiC composite tube for nuclear fuel cladding was simulated using FEA. The stress caused by the plug was distributed nonuniformly because of the friction coefficient difference between the inner surface of the tube and the plug. Hoop stress and shear stress at the tube was evaluated and the relationship between the concentrated stress at the inner layer of the tube and the fracture behavior of the tube was investigated.

Stresses around an underground opening with sharp corners due to non-symmetrical surface load

  • Karinski, Y.S.;Yankelevsky, D.Z.;Antes, M.Y.
    • Structural Engineering and Mechanics
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    • v.31 no.6
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    • pp.679-696
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    • 2009
  • The paper aims at analyzing the stress distribution around an underground opening that is subjected to non-symmetrical surface loading with emphasis on opening shapes with sharp corners and the stress concentrations developed at these locations. The analysis is performed utilizing the BIE method coupled with the Neumann's series. In order to implement this approach, the special recurrent relations for half plane were proven and the modified Shanks transform was incorporated to accelerate the series convergence. To demonstrate the capability of the developed approach, a horseshoe shape opening with sharp corners was investigated and the location and magnitude of the maximum hoop stress was calculated. The dependence of the maximum hoop stress location on the parameters of the surface loading (degree of asymmetry, size of loaded area) and of the opening (the opening height) was studied. It was found that the absolute magnitude of the maximum hoop stress (for all possible surface loading locations) is developed at the roof points when the opening height/width ratio is relatively large or when the pressure loading area is relatively narrow (compared to the roof arch radius), and contrarily, when the opening height/width ratio is relatively small or when the surface pressure is applied to a relatively wide area, the absolute magnitude of the maximum hoop stress is developed at the bottom sharp corner points.

The effect of peak cladding temperature occurring during interim-dry storage on transport-induced cladding embrittlement

  • Kim, Kyu-Tae
    • Nuclear Engineering and Technology
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    • v.52 no.7
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    • pp.1486-1494
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    • 2020
  • To evaluate transport-induced cladding embrittlement after interim-dry storage, ring compression tests were carried out at room temperature(RT) and 135 ℃. The ring compression test specimens were prepared by simulating the interim-dry storage conditions that include four peak cladding temperatures of 250, 300, 350 and 400 ℃, two tensile hoop stresses of 80 and 100 MPa, two hydrogen contents of 250 and 500 wt.ppm-H and a cooling rate of 0.3 ℃/min. Radial hydride fractions of the ring specimens vary depending on those interim-dry storage conditions. The RT compression tests generated lower offset strains than the 135 ℃ ones. In addition, the RT and 135 ℃ compression tests indicate that a higher peak cladding temperature, a higher tensile hoop stress and the lower hydrogen content generated a lower offset strain. Based on the embrittlement criterion of 2.0% offset strain, an allowable peak temperature during the interim-dry storage may be proposed to be less than 350 ℃ under the tensile hoop stress of 80 MPa at the terminal cool-down temperature of 135 ℃.

Exact deformation of an infinite rectangular plate with an arbitrarily located circular hole under in-plane loadings

  • Yang, Yeong-Bin;Kang, Jae-Hoon
    • Structural Engineering and Mechanics
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    • v.58 no.5
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    • pp.783-797
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    • 2016
  • Exact solutions for stresses, strains, and displacements of a perforated rectangular plate by an arbitrarily located circular hole subjected to both linearly varying in-plane normal stresses on the two opposite edges and in-plane shear stresses are investigated using the Airy stress function. The hoop stress occurring at the edge of the non-central circular hole are computed and plotted. Stress concentration factors (the maximum non-dimensional hoop stresses) depending on the location and size of the non-central circular hole and the loading condition are tabularized.

Deformation of a rectangular plate with an arbitrarily located circular hole under in-plane pure shear loading

  • Yang, Yeong-Bin;Kang, Jae-Hoon
    • Structural Engineering and Mechanics
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    • v.60 no.2
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    • pp.351-363
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    • 2016
  • Exact solutions for stresses, strains, displacements, and the stress concentration factors of a rectangular plate perforated by an arbitrarily located circular hole subjected to in-plane pure shear loading are investigated by two-dimensional theory of elasticity using the Airy stress function. The hoop stresses, strains, and displacements occurring at the edge of the circular hole are computed and plotted. Comparisons are made for the hoop stresses and the stress concentration factors from the present study and those from a rectangular plate with a circular hole under uni-axial and bi-axial uniform tensions and in-plane pure bending moments on two opposite edges.

Analysis of Characteristics of Spent Fuels on Long-Term Dry Storage Condition

  • Yoon, Suji;Park, Kwangheon;Yun, Hyungju
    • Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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    • v.19 no.2
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    • pp.205-214
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    • 2021
  • Currently, the interim storage pools of spent fuels in South Korea are expected to become saturated from 2024. It is required to prepare an operation plan of a domestic dry storage facility during a long-term period, with the researches on safety evaluation methods. This study modified the FRAPCON code to predict the spent fuel integrity evaluation such as the axial cladding temperature, the hoop stress and hydrogen distribution in dry storage. The cladding temperature in dry storage was calculated using the COBRA-SFS code with the burnup information which was calculated using the FRAPCON code. The hoop stress was calculated using the ideal gas equation with spent fuel information such as rod internal pressure. Numerical analysis method was used to calculate the degree of hydrogen diffusion according to the hydrogen concentration and temperature distribution during a dry storage period. Before 50 years of dry storage, the cladding temperature and hoop stress decreased rapidly. However, after 50 years, they decreased gradually and the cladding temperature was below 400 K. The initial temperature distribution and hydrogen concentration showed a parabolic line, but hydrogen was transferred by the hydrogen concentration and temperature gradient over time.

Evaluation of Optimized Ring Specimen Shape for the Hoop Behavior Test of Nuclear Fuel Clad Tube (핵연료 피복관의 후우프 거동시험을 위한 시편의 최적형상 평가)

  • 서기석
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2000.04a
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    • pp.171-178
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    • 2000
  • In order to evaluate the tensile behaviors of hoop direction for the nuclear fuel cladding tubes the shapes of specimen and jig fixtures for the ring test are decided with various conditions under the elastic-large plastic deformations. The axial displacement of the jig cylinders is converted to the circumferential direction elongations of specimen. The stress distributions on specimen are depended on the radii and locations of specimen and jig size and central angle. Therefore we calculated the stress distributions and decided the optimum shapes to get the uniform stress in the area of specimen gage length. Form the analysis the stress distributions in gate area are reviewed with the radii and location of specimen notch and the central angle of jig cylinder,. The optimum shapes of specimen and jig are proposed to the clad tube having 10.62 mm in diameter and 0.63mm in thickness for 16x16 PWR nuclear fuel assembly.

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A Numerical Study on the Hoop Tensile Test of Type IV High Aspect Ratio Hydrogen Storage Vessel (Type IV 고세장비 수소저장용기의 Hoop 인장 시험에 관한 수치해석적 연구)

  • MOONSIC PARK;JUNSOONG LEE;WONHO YOON;KYUNBUM PARK;HYEONGUK YUN;SUNGWOOK JOO
    • Journal of Hydrogen and New Energy
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    • v.34 no.1
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    • pp.32-37
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    • 2023
  • In this study, in order to propose a integrity evaluation for type IV high aspect ratio hydrogen storage vessel, a numerical analysis of the hoop tensile test and pressure test was performed using FEM software, and the results of the actual physical property test were reviewed. The property test and numerical analysis were compared, and very similar results were obtained with deviations of maximum tensile strength of 4.75% and fiber direction stress of 5.39%.

The Effects of Geometrical Shape and Post Weld Treatment on Welding Residual Stress Distribution of Weldment in Multi-pass Welded Pipe (다층용접배관의 용접부 잔류음력분포에 대한 기하학적형상과 용접후처리의 영향)

  • 김철한;조선영;김복기;배동호
    • Journal of Welding and Joining
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    • v.19 no.1
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    • pp.49-57
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    • 2001
  • In this study, the residual stress fields of multi-pass welded were analyzed by FEA under various geometrical conditions. In order to estimate the effects of pipe geometries on residual stress distribution, welding processes of each model were performed under the same heat cycles. And then, the influence of cutting off the weld bead on the residual stress redistribution was also estimated. From the results, in the range of t/D=0.05, axial residual stresses on the outer surface of the welded pipe were linearly decreased with pipe diameter increase. On the other hand, hoop residual stresses were not influenced by them. And both axial and hoop residual stresses on the outer surface of the welded pipe were increased with pipe diameter increase. But, when t/D was smaller than 0.05, they were converged in the nearly same value. The maximum residual stresses were generated at around HAZ. It in therefore necessary to consider them in welding design, strength evaluation, and analysis of fracture characteristics.

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