• Title, Summary, Keyword: Stress Analysis

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ASSESSMENT OF POSSIBILITY OF PRIMARY WATER STRESS CORROSION CRACKING OCCURRENCE BASED ON RESIDUAL STRESS ANALYSIS IN PRESSURIZER SAFETY NOZZLE OF NUCLEAR POWER PLANT

  • Lee, Kyoung-Soo;Kim, W.;Lee, Jeong-Geun
    • Nuclear Engineering and Technology
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    • v.44 no.3
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    • pp.343-354
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    • 2012
  • Primary water stress corrosion cracking (PWSCC) is a major safety concern in the nuclear power industry worldwide. PWSCC is known to initiate only in the condition in which sufficiently high tensile stress is applied to alloy 600 tube material or alloy 82/182 weld material in pressurized water reactor operating environments. However, it is still uncertain how much tensile stress is re-quired to generate PWSCC or what causes such high tensile stress. This study was performed to pre-dict the magnitude of weld residual stress and operating stress and compare it with previous experi-mental results for PWSCC initiation. For the study, a pressurizer safety nozzle was selected because it is reported to be vulnerable to PWSCC in overseas plants. The assessment was conducted by nu-merical analysis. Before performing stress analysis for plant conditions, a preliminary mock-up ana-lysis was done. The result of the preliminary analysis was validated by residual stress measurement in the mock-up. After verification of the analysis methodology, an analysis under plant conditions was conducted. The analysis results show that the stress level is not high enough to initiate PWSCC. If a plant is properly welded and operated, PWSCC is not likely to occur in the pressurizer safety nozzle.

The Influence of Sociocultural Attitude toward Appearance and Narcissism on Body Stress

  • Park, Eunhee;Lee, Sangjoo
    • Journal of Fashion Business
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    • v.18 no.6
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    • pp.1-18
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    • 2014
  • The purpose of this study is to examine the influence of sociocultural attitudes toward appearance and narcissism on body stress. Questionnaires are being administered to 206 women in their 20's-50's living in Deagu and Kyunbook province. The Frequency, factor analysis, reliability analysis, correlation analysis, regression analysis, ANOVA, and Duncan-test are used for data analysis. Sociocultural attitudes toward appearance are categorized into media appearance internalization and social recognition of appearance. Narcissism factors are found to be leadership/privilege, ostentation, and superiority. Body stress is categorized into 4 factors: weight stress, skin aging stress, body dissatisfaction, and hair stress. Sociocultural attitudes toward appearance was related to the sub-variables of narcissism, and body stress. Media appearance internalization is the sun-variable of sociocultural attitudes toward appearance and has significant effects on weight stress, skin aging stress, and body dissatisfaction sub-variables for body stress. Ostentation, and superiority being the sub-variables of narcissism, have significant effects on weight stress, skin aging stress, body dissatisfaction, and hair stress, the sub-variables for body stress. Ages of women display distinctions between the sub-variables in sociocultural attitudes toward appearance such media appearance internalization, and in narcissism such leadership/privilege, ostentation, superiority, and body stress such weight stress, skin aging stress, body dissatisfaction, and hair stress. This result can be a necessary base line data for adult women's appearance management by examining the influence of the attitude toward the appearance developed from the relationship with people around body stress.

Thermal Stress Evaluation by Elastic-Creep Analysis during Start-up of Boiler Header (보일러 헤더 기동시의 탄성 크리프 해석에 의한 열응력 평가)

  • Shin, Kyu-In;Yoon, Kee-Bong
    • Journal of the Korean Society of Safety
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    • v.24 no.2
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    • pp.17-22
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    • 2009
  • Thermal stress and elastic creeping stress analysis was conducted by finite element method to simulate start-up process of a boiler header of 500MW standard fossil power plant. Start-up temperature and operating pressure history were simplified from the real field data and they were used for the thermal stress analysis. Two kinds of thermal stress analysis were considered. In the first case only temperature increase was considered and in the second case both of temperature and operating pressure histories were considered. In the first analysis peak stress was occurred during the temperature increase from the room temperature. Hence cracking or fracture may occur at the temperature far below the operating maximum temperature. In the results of the second analysis von Mises stress appeared to be higher after the second temperature increase. This is due to internal pressure increase not due to the thermal stress. When the stress components of radial(r), hoop($\theta$) and longitudinal(z) stress were investigated, compression hoop stress was occurred at inner surface of the stub tube when the temperature increased from room temperature to elevated temperature. Then it was changed to tension hoop stress and increased because of the operating pressure. It was expected that frequent start-up and shut-down operations could cause thermal fatigue damage and cracking at the stub tube hole in the header. Elastic-creeping analysis was also carried out to investigate the stress relaxation due to creep and stabilized stress after considerable elapsed time. The results could be used for assessing the creep damage and the residual life of the boiler header during the long-tenn service.

Transient stress analysis of tracked vehicle structures under recoil impact load (주퇴충격하중을 받는 궤도차량 구조물의 천이응력해석)

  • 이영신;김용환;김영완;김동수;성낙훈
    • Journal of the korean Society of Automotive Engineers
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    • v.15 no.3
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    • pp.111-119
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    • 1993
  • In this study, the transient impact structural stress analysis of tracked vehicle structures under recoil impact load is investigated. ANSYS, ABAQUS Code are used for modelling and analytical procedures. The highest maximum Tresca stress occurs on race ring portion and its stress level is (.sigma.$_{T}$)$_{max}$ =20-40kgf/m $m^{2}$. The second highest stress occurs on upper plate of chassis and down plate of turret. The maximum stress level increases with loading direction and elevation angle. The results from liner static load analysis are very much different with impact analysis. Therefore, the practical solutions of structures under impact load can be obtained by only nonlinear transient impact analysis. The impact stress analysis of the steel vehicle structures is conducted. The maximum stress level is less than (.sigma.$_T/)$_{max}$m $m^{2}$. So, the design concept of steel structures can be adapted for new alternatives.s.s.s..s.

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Stress Analysis of the Prestressed Dies by Using FEM (유한요소법을 이용한 예압된 금형의 응력해석)

  • Yeo, Hong-Tae;Choi, Young;Hur, Kwan-Do
    • Journal of the Korean Society for Precision Engineering
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    • v.16 no.6
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    • pp.114-122
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    • 1999
  • By using the FEM, a method for the stress analysis of the presented dies has been proposed. In this method, FEM and Lame equation are used for the analysis of the die insert and the stress ring, respectively. The proposed method includes the calculation of the contact pressure between the die insert and the stress ring. To show the validity, the proposed method has been applied to the simple test problem. The results of the stress analysis have been compared with the results of ANSYS, a commercial FE-code. Cold extrusion has been simulated by using the rigid-plastic FEM and the results of the deformation analysis have been used as the input of the die structure analysis. The stress states of the prestressed extrusion die have been obtained. The stress analysis of the die insert with stress rings has also been performed during extrusion.

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Reference Stress Based Stress Analysis for Local Creep Rupture of a T-pipe (참조응력법에 입각한 T-배관 국부 크리프 파단 평가를 위한 응력해석 사례연구)

  • Shin Kyu-In;Yoon Kee-Bong;Kim Yun-Jae
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.30 no.8
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    • pp.873-879
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    • 2006
  • To investigate applicability of the reference stress approach as simplified inelastic stress analysis to estimate local creep rupture, detailed finite element stress analyses of a T-piece pipe with different inner pressure and system loading levels are performed. The reference stresses are obtained from the finite element (FE) limit analysis based on elastic-perfectly-plastic materials, from which the local reference stress for creep rupture is determined from R5. The resulting inelastic stresses are compared with elastic stresses resulting from linear elastic FE calculations. Furthermore they are also compared with the stresses from full elastic-creep FE analyses. It shows that the stresses estimated from the reference stress approach compare well with those from full elastic-creep FE analysis, which are significantly lower than the elastic stress results. Considering time and efforts for full inelastic creep analysis of structures, the reference stress approach is shown to be a powerful tool for creep rupture estimates and also to reduce conservatism of elastic stress analysis significantly.

Residual Stress Measurement of Sand Casting by ESPI Device and Thermal Stress Analysis (ESPI 장비를 활용한 사형 주조품의 잔류응력 측정 및 주조 열응력 해석)

  • Kwak, Si-Young;Nam, Jeong-Ho
    • Journal of Korea Foundry Society
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    • v.40 no.1
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    • pp.1-6
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    • 2020
  • Many studies involving a thermal stress analysis using computational methods have been conducted, though there have been relatively few experimental attempts to investigate thermal stress phenomena. Casting products undergo thermal stress variations during the casting process as the temperature drops from the melting temperature to room temperature, with gradient cooling also occurring from the surface to the core. It is difficult to examine thermal stress states continuously during the casting process. Therefore, only the final states of thermal stress and deformations can be detemined. In this study, specimens sensitive to thermal stress, were made by a casting process. After which the residual stress levels in the specimens were measured by a hole drilling method with Electron Speckle-Interferometry technique. Subsequently, we examined the thermal stresses in terms of deformation during the casting process by means of a numerical analysis. Finally, we compared the experimental and numerical analysis results. It was found that the numerical thermal stress analysis is an effective means of understanding the stress generation mechanism in casting products during the casting process.

Thermal stress analysis around a cavity on a bimetal

  • Baytak, Tugba;Bulut, Osman
    • Structural Engineering and Mechanics
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    • v.69 no.1
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    • pp.69-75
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    • 2019
  • The plates made of two materials joined to each other having the different coefficient of thermal expansions are frequently encountered in the industrial applications. The stress analysis of these members under the effect of high-temperature variation has great importance in design. In this study, the stress analysis of the experimental model developed for the problem considered here was performed by the method of photothermoelasticity. The thermal strains were formed by the mechanical way and these were fixed by the strain freezing method. For the stress measurements, the method of slicing is applied which provides three-dimensional stress analysis. The analytical solution in the literature was compared with the related stress distribution obtained from the model. Moreover, the axisymmetric finite element model developed for the problem was solved by ABAQUS and the results obtained here compared with those of the experimental model and the analytical solution. As a result of this study, this experimental method and numerical model can be used for these type of thermal stress problems which have not been comprehensively analyzed yet.

A Study on Stress Wave Propagation by Finite Element Analysis (유한요소법에 의한 2차원 응력파 전파 해석에 관한 연구)

  • 황갑운;조규종
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.18 no.12
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    • pp.3369-3376
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    • 1994
  • A finite element program for elastic stress wave propagation is developed in order to investigate the shape of stress field and analysis the magnitude of stress wave intensity at time increment. Accuracy and reliance of the finite element analysis are acquired when the element size is smaller than the product of the stress wave speed and the critical value of increasing time step. In the finite element analysis and theoretical solution, the longitudinal stress wave is propagated to the similar direction of impact load, and the stress wave intensity is expressed in terms of the ratio of propagated area. The direction of shear wave is declined at an angle of 45 degrees compared with longitudinal stress wave and the speed of shear wave is half of the longitudinal stress wave.

Analysis of Principal Stresses of O-Ring under Uniform Deformation and Internal Pressure by Stress Freezing Method (응력동결법에 의한 고압기밀용 오링의 주응력 해석)

  • Nam, Jeong-Hwan;Hawong, Jai-Sug;Kim, Young-Tak;Park, Sung-Han;Shin, Dong-Chul
    • Proceedings of the KSME Conference
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    • pp.150-154
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    • 2008
  • In this research, stress components and principal stresses of O-ring under internal pressure and under uniform squeeze rate were obtained from the stress freezing method of photoelastic experiment and photoelastic experimental Hybrid method for 3-dimensional problems. The obtaining processes of those were introduced. It was certified that the processes of those are effective for the 3-dimensional stress analysis of structures. Stress freezing method, the obtaining processes of those and photoelastic experimental hybrid method were effectively applied to the stress analysis of O-ring made from rubber that under uniform deformation and internal pressure. Stress components and principal stress of Oring under uniform squeeze rate and under internal pressure were analyzed.

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