• Title, Summary, Keyword: 고주기피로

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Forced Vibration and Structural Response Prediction for Impeller in Resonant Conditions due to Diffuser Vanes (디퓨저 베인에 기인한 공진조건에서의 임펠러 강제진동 및 구조응답 예측)

  • Kim, Yongse;Kong, Dongjae;Shin, SangJoon;Park, Kihoon;Im, Kangsoo
    • Journal of the Korean Society of Propulsion Engineers
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    • v.22 no.4
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    • pp.24-35
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    • 2018
  • Impeller blades in the centrifugal compressor are subjected to periodic aerodynamic excitations by interactions between the impeller and the diffuser vanes (DV) in resonant conditions. This may cause high cycle fatigue (HCF) and eventually result in failure of the blades. In order to predict the structural response accurately, the aerodynamic excitation and the major resonant conditions were predicted using unsteady computational fluid dynamics (CFD) and structural analysis. Then, a forced vibration analysis was performed by going through one-way fluid-structure interaction (FSI). A numerical analysis procedure was established to evaluate the structural safety with respect to HCF. The numerical analysis procedure proposed in this paper is expected to contribute toward preventing HCF problems in the initial design stage of an impeller.

Structural Stability Evaluation of Impeller in Resonant condition due to Diffuser vanes (디퓨저 베인에 의한 공진조건에서의 임펠러 구조 안정성 평가)

  • Kim, Yongse;Kong, Dongjae;Shin, Sangjoon;Im, Kangsoo;Park, Kihoon
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • pp.877-880
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    • 2017
  • Impeller blades in the centrifugal compressor are subjected to static loads due to the high-speed rotation and steady aerodynamic forces. At the same time, aerodynamic excitations by the interaction between the impeller and the diffuser vanes(DV) periodically excite the impeller blades in resonant conditions, which may lead to high cycle fatigue (HCF) and eventually result in failure of the blades. In order to predict the structural response accurately, the aerodynamic excitation and the major resonant conditions were predicted by performing the unsteady flow analysis and modal analysis using ANSYS. Next, a unidirectional forced vibration analysis was performed by using fluid-structure interaction (FSI) method, and the safety of HCF was evaluated based on the results.

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A Fatigue Analysis of the Common Stand in a Steel Mill through the Evaluation of Thermal Effects (열영향 평가를 통한 제철공장 공동가대의 피로해석)

  • Park, Y.K.;Kim, J.G.
    • Journal of Power System Engineering
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    • v.10 no.4
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    • pp.90-98
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    • 2006
  • 본 연구에서는 체철공장에서 래이들 카의 매우 높은 열에 주기적으로 빈번히 노출되는 공동가대의 열적 피해에 대한 체계적인 평가를 수행하였다 먼저 실험과 함께 유한요소법을 사용한 열해석이 수행되었다. 기존 공동가대와 향후 설치될 신 공동가대 모두에 대한 적합한 기준을 검증하기위하여 가장 심각한 상태에 대한 열평가가 포함되었다. 또한 공동가대에 적합한 방열판의 설계를 위하여 실험결과에 근거한 수치해석이 사용되었다. 마지막으로 새로 설치될 공동가대의 안전성과 내구성을 평가하기위한 피로해석을 수행하였다. 6m 신형공동가대의 열응력해석 및 피로해석 결과 기존 공동가대보다는 취약하나 설치 및 사용에는 문제가 없음을 확인하였다.

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Evaluation of fatigue poperties of base and weld metal for API 5L X65 pipeline (API 5L X65 배관 모재 및 용접부 피로특성 평가)

  • Kim, Cheol-Man;Baek, Jong-Hyun;Kim, Woo-Sik
    • Proceedings of the KSME Conference
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    • pp.44-48
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    • 2001
  • The pipelines for natural gas transmission were buried in the ground of 1.5m depth. The pipelines were continuously subjected to vehicle load and internal pressure change by the quantity consumed of natural gas. In this paper, high cycle fatigue properties of natural gas transmission pipelines were studied. Fatigue specimens were obtained from the base and weld metal of circular pipe. Fatigue strength increased with increasing yield strength. Especially, the fatigue strength of base metal was higher than the yield strength of base metal and the fatigue strength of weld metal by manufactured process of TMCP.

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Fatigue Limit of Copper Film (동 박막의 피로한도)

  • Huh, Yong-Hak;Kim, Dong-Jin;Lee, Hae-Moo;Hong, Sung-Gu;Park, Jun-Hyub
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.33 no.10
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    • pp.1158-1162
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    • 2009
  • Fatigue limit of the copper film coated by Sn was estimated using Goodman diagram and Gerber diagram. To obtain the high cycle fatigue life curve, S-N curve, of the film, the high cycle fatigue test was carried out by applying the constant amplitude load to the film specimen with three different stress ratio of 0.05, 0.3 and 0.5 and the frequency of 40 Hz at room temperature in air. The free-standing film specimen 15.26${\mu}m$ thick was fabricated by etching process. The fatigue limits and S-N curves at the respective stress ratios were determined from the experimental works. It was shown that the S-N curves were dependent on the stress ratio and the fatigue limit was increased with decreasing the stress ratio. The dependency of the fatigue behavior was presented in empirical relationship. Using these relationships, the fatigue limit was predicted.

High Cycle Fatigue Life Evaluation of Damaged Composite Rotor Blades (손상된 복합재 로터 블레이드의 고주기 피로수명 평가)

  • Kee, Young-Jung;Kim, Seung-Ho;Han, Jeong-Ho;Jung, Jae-Kwon;Heo, Jang-Wook
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.36 no.10
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    • pp.1275-1282
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    • 2012
  • Helicopter rotor systems are dynamically loaded structures with many composite components such as the main and the tail rotor blades. The fatigue properties of composite materials are extremely important to design durable and reliable helicopter rotor blades. The safe-life methodology has generally been used in the helicopter industry to substantiate dynamically loaded composite components. However, it cannot be used to evaluate the strength reducing effects of flaws and defects that may occur during manufacturing and operational usage. The damage tolerance methodology provides a proper means to overcome this shortcoming; however, it is difficult to economically apply it to every composite component. The flaw tolerant methodology is an equivalent option to the damage tolerance methodology for civil and military rotorcraft. In this study, the flaw tolerant safe-life evaluation is described and illustrated by means of successful application to substantiate the retirement time of composite rotor blades.