• Title/Summary/Keyword: Stress-Strength Analysis

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A study on design and structural strength analysis of positioner in robot overlay welding system of ball for ball-valve (볼밸브용 볼의 로봇 육성용접시스템에서 포지셔너의 설계 및 구조강도해석에 관한 연구)

  • Lee, Jong-Hwan;Lho, Tae-Jung
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.16 no.3
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    • pp.1639-1644
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    • 2015
  • A study on design and structural strength analysis of a positioner in robot overlay welding system of a ball for ball-valves. Turning-unit of positioner modeled, analysis was conducted by assuming the beam. Turning-unit is applied to the stress, it was shown by 366.85MPa when weight of the ball is $9,000kg_f$. This value is higher than the yield strength of the material. Based on the results of previous, it was modeled the turning-unit by modifying. Results of analysis by a modified modeling, The value of stress was confirmed to 296.11MPa. This value is a value lower than the yield strength of the material, it was found to support the weight of the ball.

Proposed New Model for the Stress-Strain Relationship of Ultra High-Strength Concrete (초고강도 콘크리트의 응력-병형률 모델 제안)

  • 박훈규;이정화;윤영수;장일영
    • Proceedings of the Korea Concrete Institute Conference
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    • 1997.04a
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    • pp.406-412
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    • 1997
  • This paper presents the newly developed model for the stress-strain relationship of ultra high- strength concrete on the basis of the more refined statistical to analysis the various test results available in the literature to be more rigorous in accuracy and generalized scheme. Through the comprehensive analysis of the previously existing equations for each model, multiple curves equation has turned out to be most appropriate to simulate the linearly varying ascending branch and brittle type of descending one. The principal variables to model the stress-strain relationship such as the modulus of elasticity, ultimate strain and deformation characteristics due to stress softening phenomenon were extensively studied to be simplified in the function of the concrete compressive strength.

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Stress Comparison on Welded Connection between Detail FE Model and Classical Calculation (계산 방법론에 따른 용접부 응력 평가 및 비교(FE 상세 모델 vs 수 계산))

  • Song, Moon-Sung;Jeong, Sang-Woong
    • Proceedings of the KSR Conference
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    • 2010.06a
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    • pp.621-626
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    • 2010
  • According to development of method and device of Finite Element Analysis, the strength of welded joint is demonstrated by Finite Element Analysis not classical calculations. On the FEA, all of the joints for carbody are assumed to be ideal connections and the yield stress of welded joint is assumed to be the same to base metal. On these assumption, FEA is appropriate to evaluate the overall stability and strength of whole carbody. The classical calculation is appropriate to evaluate strength of specific welded joint and to determine the weld method and properties. Some project request strength calculation of the specific welded joints in addition to FEA, because of the demonstration of stability. The objective of this paper is the check of the consistency of the FEA result for the welded joints by the stress comparison between Detailed FE Model and classical calculation and the evaluation of the reliability of FEA result.

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A Stochastic Analysis in Fatigue Strength of Degraded Steam Turbine Blade Steel (열화된 증기 터빈블레이드의 피로강도에 대한 확률론적 해석)

  • Kim, Chul-Su;Jung, Hwa-Young;Kim, Jung-Kyu
    • Proceedings of the KSME Conference
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    • 2001.06a
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    • pp.262-267
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    • 2001
  • In this study, the Reliability of degraded steam turbine blade was evaluated using the limited fatigue data. The statistical estimation of limited fatigue data implies that some unknown uncertainties which may be involved in fatigue reliability analysis. Therefore, an appropriate distribution in the fatigue strength was determined by the characteristic distribution - linear correlation coefficient, fatigue physics, error parameter. 3-parameter Weibull distribution is the most appropriate distribution to assume for infinite region. The load applied on the blade is mainly tensile. The maximum Von-Mises stress is 219.4 MPa at the steady state service condition. The failure probability($F_p$) derived from the strength-stress interference model using Monte carlo simulation under variable service condition is 0.25% at the 99.99% confidence level.

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The Effects of Sheet Strength and Thickness on Bending Behavior of Steel Pipes (소재강도와 두께가 파이프 굽힘변형의 꺽임발생 거동에 미치는 영향)

  • 박기철;이형진
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.19 no.9
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    • pp.2071-2081
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    • 1995
  • In order to examine the effects of yield stress, tensile strength and thickness on the buckling behavior during bending of pipes, the nonlinear finite element analysis of the 3-point bending tests was carried out using the commercial software (ABAQUS) under the condition of L4(2$^{3}$) performed according to the designed condition. Form the analysis of simulation results, it was found that yield stress and thickness were the major factors on buckling load at pipe bending and tensile strength gave little influence because the plastic strain and plastic zone are small. For the punch displacement to the occurrence of buckling, thickness is a major factor and yield stress and tensile strength are the minor factors.

Proposal of the Penalty Factor Equations Considering Weld Strength Over-Match

  • Kim, Jong-Sung;Jeong, Jae-Wook;Lee, Kang-Yong
    • Nuclear Engineering and Technology
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    • v.49 no.4
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    • pp.838-849
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    • 2017
  • This paper proposes penalty factor equations that take into consideration the weld strength over-match given in the classified form similar to the revised equations presented in the Code Case N-779 via cyclic elastic-plastic finite element analysis. It was found that the $K_e$ analysis data reflecting elastic follow-up can be consolidated by normalizing the primary-plus-secondary stress intensity ranges excluding the nonlinear thermal stress intensity component, $S_n$ to over-match degree of yield strength, $M_F$. For the effect of over-match on $K_n{\times}K_{\nu}$, dispersion of the $K_n{\times}K_{\nu}$ analysis data can be sharply reduced by dividing total stress intensity range, excluding local thermal stresses, $S_{p-lt}$ by $M_F$. Finally, the proposed equations were applied to the weld between the safe end and the piping of a pressurizer surge nozzle in pressurized water reactors in order to calculate a cumulative usage factor. The cumulative usage factor was then compared with those derived by the previous $K_e$ factor equations. The result shows that application of the proposed equations can significantly reduce conservatism of fatigue assessment using the previous $K_e$ factor equations.

Reliability Analysis in Fatigue Strength of Connecting Rod (커넥팅 로드의 피로강도에 대한 신뢰성 해석)

  • Kim, Cheol-Su;Lee, Jun-Hyeong;Kim, Jeong-Gyu
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.25 no.10
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    • pp.1651-1658
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    • 2001
  • It is necessary to evaluate fatigue strength and reliability of the connecting rod which is core part in automotive engine to assure the high level of durability of automobile. For this purpose, the loading conditions in automotive engine is obtained by the dynamic analysis. Based on these results, the critical section was identified by the finite element analysis. The fatigue strength under constant amplitude was evaluated and the mean of the fatigue limit at R = -2.27 derived from the staircase method was 311.2MPa. And the failure probability( F$\sub$p/ ) derived from the strength-stress interference model is 0.0003% at the 99.99% confidence level and the mean factor of safety was 4.2.

The Forging Die Design of Scroll Rotor by using the 3-D FEM Analysis (3차원 유한요소해석을 이용한 스크롤 로터의 단조 금형 설계)

  • Lee, Young-Seon;Lee, Jung-Hwan
    • Proceedings of the KSME Conference
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    • 2001.06c
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    • pp.111-115
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    • 2001
  • The die design for hot forging was investigated for manufacturing precisely of scroll rotor made with Al-Si alloy. A scroll rotor is a non-symmetric 3-D shape part, having involute wraps. Disk-shaped billet of Al-Si alloy was extruded to wraps and boss simultaneously. Because the involute wraps is not axi-symmetric, the flow velocity and the stress of die is very much different at each portion. Moreover, the die in wraps portion is a cantilever beam and fractured. In this paper, the analysis of forming and die stress is investigated using the FEM tool, DEFORM-3D. The tensile strength of tool material is $250kg/mm^{2}$. From the analysis results, we can find the maximum principal stress of die is over the fracture strength and redesign the die. The prototype forged part is superior in net shaping and microstructure.

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Estimation of Fatigue Strength in Resistance Spot Weldment of the Vehicle Body (차체 저항 점 용접부 피로수명 예측)

  • 손광재;양영수;조성규;장상균
    • Journal of Welding and Joining
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    • v.20 no.2
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    • pp.59-64
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    • 2002
  • When the vehicle travels in an actual road, resistance spot weldments of the vehicle structure are exposed to complex loading state. Since the fatigue strength in resistance spot weldment of vehicle body can be determined by effect of residual stresses and loading state of driving, estimating actual loading state and considering residual stress effect are needed. In this study, Fatigue stress-fatigue life relation concerned residual stress effect was obtained by thermo elastic plastic finite element analysis. And applied loading in resistance spot weldments of vehicle body was calculated by dynamic analysis. Presumption of fatigue life was performed using proposed method

Design of Excavator Boom Structure Based on Fatigue Strength of Weldment(I) (용접부 피로강도를 고려한 굴삭기 붐 구조물 설계(I))

  • Park, Sang-Chul
    • Journal of Welding and Joining
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    • v.28 no.5
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    • pp.58-63
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    • 2010
  • The purpose of this study is to develop improved boom structures with reliable fatigue strength of weldment and lower production cost. For that purpose, multibody dynamic analysis was performed to evaluate forces acting on arm & boom cylinders and joints of boom structure during operation of an excavator for three working postures, then stress analysis was made to investigate stress distribution around diaphragms at the bottom plate of boom structures which was known to be susceptible to fatigue failures of welded joints, and finally boom structure with optimum arrangement of diaphragms was proposed. This work basically consists of the following two parts: part 1 focuses on multibody dynamic analysis of excavators during operation and part 2 includes evaluations of fatigue strength of welded joints for modified boom structures.