• Title/Summary/Keyword: 응력스펙트럼

Search Result 110, Processing Time 0.035 seconds

Evaluation of the Seismic Integrity of a Centrifugal Pump using Response Spectrum Analysis (응답 스펙트럼 해석을 이용한 원심펌프의 내진 건전성 평가)

  • Choi, Myung-Jin;Yoo, Ji-Woo
    • Journal of the Korean Institute of Gas
    • /
    • v.14 no.6
    • /
    • pp.44-50
    • /
    • 2010
  • Vibration responses of a centrifugal pump required dynamic analysis for seismic qualification, were calculated by using spectrum analysis, which is known to be very simple compared with time domain analysis. Modal analysis was performed and the results were utilized in the spectrum analysis. The vibration responses calculated from the spectrum analysis were more conservative than those from the time domain analysis, that is, the former can be used as safer in design process. The pump was qualified for the specified seismic service conditions as specified in IEEE 344-1987. The maximum stresses were less than allowable stress limits. Based on the analysis results, it is concluded that the pump meets all the dynamic requirements of the applicable codes, standards, and technical specification.

A Study on the Residual stress of Diamond-like Carbon Films Deposited by RF PECVD (RF PECVD로 증착된 다이아몬드상 탄소막의 잔류응력에 관한 연구)

  • Choi, Woon;Nam, Seung-Eui;Kim, Hyoung-June
    • Korean Journal of Materials Research
    • /
    • v.6 no.12
    • /
    • pp.1162-1169
    • /
    • 1996
  • rf 플라즈마 화학증착을 이용하여 증착된 hydrogenated DLC막의 잔류응력 거동에 대해 조사하였다. 합성된 DLC막의 압축 잔류응력은 이온 에너지뿐만 아니라 이온/원자 유입량 비에 의해 영향을 받는 것으로 조사되었다. 잔류응력의 최대치는 이온/원자 유입량비가 증가할수록 낮은 이온 에너지 구간에서 일어나며 그 값은 증가하였다. 이온 에너지에 따른 DLC막의 결합 구조의 변형을 Raman 스펙트럼을 이용하여 분석하였다. DLC막의 잔류응력은 sp3결합의 net working이 최대가 되는 점에서 최대치를 보이며, 이는 sp3 net working에 의한 부피팽창 요인에 기인하는 것으로 생각된다. DLC막 내의 유입되는 수소는 잔류응력의 직접적인 원인으로 작용하지 않는 것으로 분석되었다.

  • PDF

Analysis of Characteristics of Seismic Source and Response Spectrum of Ground Motions from Recent Earthquake near the Backryoung Island (최근 백령도해역 발생지진의 지진원 및 응답스펙트럼 특성 분석)

  • Kim, Jun-Kyoung
    • Geophysics and Geophysical Exploration
    • /
    • v.14 no.4
    • /
    • pp.274-281
    • /
    • 2011
  • We analysed ground motions form Mw 4.3 earthquake around Backryoung Island for the seismic source focal mechanism and horizontal response spectrum. Focal mechanism of the Backryoung Islands area was compared to existing principal stress orientation of the Korean Peninsula and horizontal response spectrum was also compared to those of the US NRC Regulatory Guide (1.60) and the Korean National Building Code. The ground motions of 3 stations, including vertical, radial, and tangential components for each station, were used for grid search method of moment tensor seismic source. The principal stress orientation from this study, ENE-WSW, is consistent fairly well with that of the Korean Peninsula. The horizontal response spectrum using 30 observed ground motions analysed and then were compared to both the seismic design response spectra (Reg Guide 1.60), applied to the domestic nuclear power plants, and the Korean Standard Design Response Spectrum for general structures and buildings (1997). Response spectrum of 30 horizontal ground motions were used for normalization with respect to the peak acceleration value of each ground motion. The results showed that the horizontal response spectrum revealed higher values for frequency bands above 3 Hz than Reg. Guide (1.60). The results were also compared to the Korean Standard Response Spectrum for the 3 different soil types and showed that the vertical response spectra revealed higher values for the frequency bands below 0.8 second than the Korean Standard Response Spectrum (SD soil condition). However, through the qualitative improvements and quantitative enhancement of the observed ground motions, the conservation of horizontal seismic design response spectrum should be considered more significantly for the higher frequency bands.

Estimation of Spectrum Decay Parameter χ and Stochastic Prediction of Strong Ground Motions in Southeastern Korea (한반도 남동부에서 부지효과를 고려한 스펙트럼 감쇠상수 χ 추정 및 강지진동의 추계학적 모사)

  • 조남대;박창업
    • Journal of the Earthquake Engineering Society of Korea
    • /
    • v.7 no.6
    • /
    • pp.59-70
    • /
    • 2003
  • We estimated the spectrum decay parameter $\chi$ and the stress parameter ($\Delta$$\sigma$) in southeastern Korea. Especially, we propose a procedure to compute site-independent $\chi$$_{q}$ and dependent $\chi$$_{s}$ values, separately, This procedure is to use the coda normalization method for the computation of site independent Q or corresponding $\chi$$_{q}$ value as the first step followed by the next step, the computation of $\chi$$_{s}$ values for each site using the given $\chi$$_{q}$ value evaluated at the first step, For the estimation of stress parameter, we used seismic data monitored from three earthquakes occurred near Gyeongju in 1999 with the method of Jo and Baag, In addition, we simulated strong ground motion using the $\chi$ value and the stress parameter, In this case, we calculated the $\chi$ value with conventional method. The $\chi$ value of 0.016+0.000157R and the stress parameter of 92-bar was applied to the stochastic simulation, At last, we derived seismic attenuation equation using results of the stochastic prediction, and compared these results with some others reported previously.ported previously.

Prediction of Fatigue Life for Composite Rotor Blade of Multipurpose Helicopter Using Strength Degradation Model (강도저하모델을 이용한 다목적헬리콥터용 복합재로터깃 피로수명예측)

  • 권정호;서창원
    • Composites Research
    • /
    • v.14 no.2
    • /
    • pp.50-59
    • /
    • 2001
  • The predictions of residual strength evolution and fatigue life of full scale composite rotor blade for multipurpose helicopter were studied using a strength degradation model. Flight-by-flight load spectrum was developed on the basis of FELIX standard spectrum data. The laminated structural analysis was also performed to obtain corresponding local stress and/or strain spectra for each ply of laminate skin and glass roving spar structures around the blade root where fatigue damage was severely anticipated.

  • PDF

Design Optimization of a Wing Structure under Multi Load Spectra using PSO algorithm (PSO 알고리즘을 이용한 다중 하중 스펙트럼 하에서의 항공기 날개 구조부재의 최적 설계 연구)

  • Park, Kook Jin;Park, Yong Jin;Cho, Jin Yeon;Park, Chan Yik;Kim, Seung Jo
    • Journal of the Korean Society for Aeronautical & Space Sciences
    • /
    • v.40 no.11
    • /
    • pp.963-971
    • /
    • 2012
  • In this paper, development of optimal design tools for wing structure is described including multi load spectra condition and fatigue analysis. Two dimensional CFD result are used for calculating aerodynamic force. Design variables are composed of a number of rib and spar, positions, and thickness of each structural member. The mission profile for fatigue analysis is composed based upon the results of CFD analysis, the flight-by-flight spectra method, the excessive curves for gust loads. Minor's rule was used to deal with multi-load condition. Stress analysis and fatigue analysis are performed to calculate objective functions. Particle Swarm Optimization(PSO) algorithm was used to apply to problems which have dozens of design variables.

A Multiple Crack Propagation Analysis considering Initial Flaw and Stress Order in Riveted Specimens (리벳 시편의 초기결함과 응력배열을 고려한 다중균열진전해석)

  • Kim, Jung-Hoon;Zi, Goang-Seup;Kim, Min-Sung;Kong, Jung-Sik
    • Proceedings of the Computational Structural Engineering Institute Conference
    • /
    • 2010.04a
    • /
    • pp.326-329
    • /
    • 2010
  • 항공기는 전체 수명동안 무수한 반복하중에 노출되기 때문에, 동체에 피로로 인한 다중균열이 불가피하게 발생하게 된다. 이 다중균열은 기체의 강성을 저하시킬 뿐 만 아니라, 종국적으로는 해당 기체구조의 파단을 야기할 수 있다. 초기 결함과 운용 중에 작용되는 응력 스펙트럼은 구조물의 피로수명에 영향을 끼치며 고려해야 한다. 본 논문에서는 초기결함 특성을 파악하기 위한 등가초기결함크기 분포를 산출하고 리벳 시편의 다중균열모델에 대해서 초기결함과 응력배열을 고려한 해석을 수행하였다.

  • PDF

Comparison of Allowable Axial Stress Provisions of Cylindrical Liquid Storage Tanks under Seismic Excitation (지진 하중을 받는 원통형 플랜트 탱크 구조물의 축방향 허용압축응력 설계기준 비교 연구)

  • Oh, Chang Kook;Lee, So Ri;Park, Jang Ho;Bae, Doobyong
    • Journal of Korean Society of Steel Construction
    • /
    • v.28 no.4
    • /
    • pp.293-301
    • /
    • 2016
  • Stability of cylindrical liquid storage tanks under seismic excitation could prevent catastrophic disaster of human life and economic loss. Domestic provisions on allowable compressive stress in tank walls to prohibit buckling failure are either incomplete or inconsistent, so foreign specifications such as API 650, BS EN 1998-4:2006 or New Zealand Standards are employed in stability design. In this study, response spectrum analyses are performed for plant tanks having different ratios of height to diameter or diameter to thickness to calculate hydrodynamic pressure on tank walls. Then nonlinear buckling analyses are conducted to estimate magnitude of buckling stress. By comparing analysis results with those from foreign design specifications, appropriate domestic design provisions are suggested.

Fatigue Behavior and Probabilistic Fatigue Analysis of Concrete Offshore Structures (콘크리트 해양구조물(海洋構造物)의 피로거동(疲勞擧動)과 확률론적(確率論的) 피로해석(疲勞解析))

  • Oh, Byung Hwan;Kim, Jee Sang
    • KSCE Journal of Civil and Environmental Engineering Research
    • /
    • v.8 no.3
    • /
    • pp.31-41
    • /
    • 1988
  • Recently, the offshore structures are increasingly constructed to explore the natural resources. These offshore structures are to be designed to resist the repetitive wave forces. A probabilistic method for the fatigue analysis of offshore concrete structures is presented in this study. The present spectral fatigue analysis calculates wave forces first and then the transfer functions for unit waves from which stress spectra are determined. The calculated fatigue stresses may then be used to evaluate the fatigue damage of concrete structures. A simplified model for the estimation of fatigue damage of the structures, which employs only the probabilistic moments of the peak stress distribution without direct integration, is also proposed. The present study allows more realistic fatigue analysis of offshore concrete structures.

  • PDF

Development of an Analysis Model for UPS System of LNG Receiving Terminal Facilities (천연가스 생산기지 내 UPS시스템의 해석모델 개발)

  • Kook, Seung-Kyu;Hong, Seong-Kyeong;Kim, Joon-Ho;Choi, Won-Mog;Park, Young-Ho
    • Journal of the Computational Structural Engineering Institute of Korea
    • /
    • v.29 no.6
    • /
    • pp.539-545
    • /
    • 2016
  • UPS system in the liquefied natural gas(LNG) receiving terminal is one of the fundamental equipment that need to sustain operation during earthquake. In this study, modal identification test of UPS system was performed based on IEEE Std. 693-2005 and natural frequencies and modal damping, mode shapes had been identified. In addition, tri-axial time history test was performed to check the behavior and stress of the equipment during earthquake. Eigenvalue analysis was performed and analysis model was modified by reflecting the results of the test. Static analysis by dead weight and response spectrum analysis were performed to compare the combined stresses with the stress results of test. Dynamic characteristics and combined stresses under seismic load condition of the improved analysis model were similar to the test results and in this regard the compatibility was proved.