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발전용 증기터빈 밸브 케이싱의 유한요소해석과 주조결함 평가 방법
이부윤,김원진,신현명,Lee Boo-Youn,Kim Won-Jin,Shin Hyun-Myung 한국마린엔지니어링학회 2005 한국마린엔지니어링학회지 Vol.29 No.5
Stresses of main stop valve and control valve casings for the steam turbines of power plants are analyzed by the finite element method. The stress intensity is obtained to check the results on the basis of the design criteria of ASME boiler and pressure vessel code. To verify accuracy of the finite element analysis. analyzed stresses are compared with those measured during the hydrostatic pressure test. Stress category drawings. which play an important role in evaluating casting defects, are produced from the analysis results, and important points in casting of the valve casings are discussed in terms of the stress category.
경계요소법에 의한 축대칭 탄성체의 형상설계 민감도해석을 위한 직접미분법과 터빈 디스크의 형상최적설계
이부윤,Lee, Bu-Yun 대한기계학회 1996 大韓機械學會論文集A Vol.20 No.5
A direct differentiationmethod is presented for the shape design sensitivity analysis of axisymmeetric elastic solids. Based on the exisymmetric boundary integralequaiton formulation, a new boundary ntegral equatio for sensitivity analysis is derived by taking meterial derivative to the same integral identity that was used in the adjoint variable melthod. Numerical implementation is performed to show the applicaiton of the theoretical formulation. For a simple example with analytic solution, the sensitivities by present method are compared with analytic sensitivities. As an application to the shape optimization, an optimal shape of a gas turbine disc toinimize the weight under stress constraints is found by incorporating the sensitivity analysis algorithm in an optimizatio program.
섬유판 제작용 압연프레스 가열드럼의 피로수명 해석과 구조설계 개선에 관한 연구
이부윤,Lee Boo Youn 한국마린엔지니어링학회 2005 한국마린엔지니어링학회지 Vol.29 No.2
Stress and fatigue life analyses are performed to enhance a fatigue life of a heating drum of the roller press for medium density fiberboard. The finite element method employing the submodel is used to analyze stress concentration in the journal of the heating drum. The fatigue life is evaluated by the stress-life theory. Two modified designs of the journal are suggested and evaluated to reduce the maximum stress and to increase the fatigue life Their structural reliabilities are verified in terms of the yield strength and the design life.
시험 규격을 고려한 자동차 페달 암의 구조해석과 위상최적화
이부윤,이현우,Lee Boo-Youn,Lee Hyun-Woo 한국마린엔지니어링학회 2006 한국마린엔지니어링학회지 Vol.30 No.5
Finite element analysis is performed to evaluate structural reliability of an automotive pedal arm under conditions of the stiffness, the load and the endurance test specifications. Results of the analysis shows that the pedal arm is safe enough under the tests. A topology optimization is numerically implemented, overall shape of the pedal arm being verified to be reasonable, A design concept to insert holes in the arm is established, which may be used to reduce its weight.
석탄화력발전소 보일러의 멤브레인벽을 위한 등가 쉘요소의 직교이방성 탄성상수 결정 방법
이부윤(Boo-Youn Lee) 한국기계가공학회 2020 한국기계가공학회지 Vol.19 No.3
In this study, we proposed a method to replace the solid finite element model of the boiler membrane wall for coal-fired power plants using an equivalent shell model. The application of a bending load to the membrane wall creates greater displacement at both ends of the central portion when compared with the middle when an isotropic elastic constant is used in the shell model. This is inconsistent with the results of the solid model where the central portion is uniformly deformed. Here, we presented a method to determine the orthotropic elastic constants of the shell model in terms of bending stiffness and vibration characteristics to solve this problem. Our analysis of the orthotropic shell model showed that the error ratio was 0.9% for the maximum displacement due to the bending load, 0.3% for the first natural frequency, and 2.5% for the second natural frequency when compared with the solid model. In conclusion, a complicated boiler membrane wall composed of a large number of pipes and fins can be replaced with a simple shell model that shows equivalent bending stiffness and vibration characteristics using our proposed method.
유럽기준을 적용한 배열회수보일러 고압드럼의 응력 및 피로 평가
이부윤(Boo Youn Lee) 대한기계학회 2018 大韓機械學會論文集A Vol.42 No.9
배열회수보일러 고압드럼에 대하여 EN Code와 ASME Code를 적용하여 설계피로를 평가하였다. 설계조건의 응력과 과도운전조건의 응력범위는 EN Code의 평가기준을 만족하였다. 과도운전조건을 고려하여 EN Code와 ASME Code를 적용하여 설계피로를 계산하였다. 대표적 위치인 쉘-노즐 용접부 핫스팟과 비용접부인 보어의 피로수명은 두 Code의 피로 평가기준을 만족하였다. 두 Code에 의한 누적피로 사용계수는 비용접부에서는 비슷한 수준이지만, 용접부에서는 EN Code가 ASME Code보다 보수적인 결과를 보였다. 본 연구에서 제시된 EN Code의 적용 방법 및 실제 적용 사례는 유사한 압력용기의 설계검증 과정에서 널리 활용될 수 있을 것으로 기대된다. The design fatigue of a high-pressure drum in a heat recovery steam generator was evaluated according to EN and ASME codes. The stress for the design condition and stress range for transient operating conditions are demonstrated to satisfy the criteria of the EN code. The cumulative fatigue usage factors at several representative shell–nozzle weld hotspots and the bores were calculated by applying both codes, and are shown to satisfy the criteria. It was found that the usage factors calculated using the two codes are similar in the non-welded area, but the EN code produces more conservative results for the welded areas than the ASME code. The method for the practical application of the EN code presented in this study can be widely used in the design verification process of similar pressure vessels.
구조해석을 통한 하부냉동실형 빌트인 냉장고 도어의 처짐량 평가
이부윤(Boo-Youn Lee) 한국기계가공학회 2020 한국기계가공학회지 Vol.19 No.2
In this study, we developed a finite element model for the built-in bottom-freezer type refrigerator and then used the structural analysis method to analyze and evaluate the deflection of the doors. We tested the validity of the developed analytical model by measuring the deflection of the hinge when loads were applied to the upper and lower hinges of the refrigerating compartment and compared these with the analysis results. The comparison of the vertical displacement of the measured result and the analysis result showed an error ratio of up to 12.8%, which indicates that the analytical model is consistent. Using the analytical model composed of the cabinet, hinges and doors, we performed analyses for two cases: both doors closed, and the refrigerating door open. Since the maximum vertical displacement of the refrigerating compartment door (R-door) with the food load is smaller than the gap between the lower surface of the R-door and the upper surface of the freezer compartment door (F-door), it is judged that the R-door and the F-door do not contact when the doors are opened or closed. In addition, the analysis result showed that the difference between the vertical displacement at the hinge on the opposite side and the hinge side of the R-door is favorably smaller than the management criterion of the refrigerator manufacturer.
빌트인 냉장고 댐핑힌지의 응력해석 및 파손방지를 위한 설계개선
이부윤(Boo-Youn Lee) 한국기계가공학회 2020 한국기계가공학회지 Vol.19 No.2
The damping hinge of a built-in refrigerator was examined in terms of its stress and fatigue life. Analysis of the initial design showed that stress concentration occurred at the concave surface of the hinge lever, which was broken during the door opening-and-closing endurance test of the prototype. The maximum von Mises stress at this location exceeded the yield strength. In addition, Goodman fatigue analysis of the initial design showed that the fatigue life at this location was consistent with the failure observed during the endurance test. Based on these results, an improved design for the damping hinge was derived. Analysis of this improved design showed that the stress concentration in the hinge lever of the initial design was eliminated. In this case, the maximum stress occurred at the position where the hinge lever was in contact with the door stopping pin, and the maximum von Mises stress was smaller than the yield strength. Goodman fatigue analysis of the improved design indicated that the fatigue life of the entire damping hinge was infinite. It was therefore concluded that the improved design does not suffer from fatigue damage during the endurance test.
ASME Boiler & Pressure Vessel Code에 따른 배열회수보일러 기수분리기의 피로 평가
이부윤(Boo-Youn Lee) 한국기계가공학회 2018 한국기계가공학회지 Vol.17 No.4
The present research deals with a finite element analysis and fatigue evaluation of a steam separator of a high-pressure evaporator for the Heat Recovery Steam Generator (HRSG). The fatigue during the expected life of the HRSG was evaluated according to the ASME Boiler and Pressure Vessel Code Section VIII Division 2 (ASME Code). First, based on the eight transient operating conditions prescribed for the HRSG, temperature distribution of the steam separator was analyzed by a transient thermal analysis. Results of the thermal analysis were used as a thermal load for the structural analysis and used to determine the mean cycle temperature. Next, a structural analysis for the transient conditions was carried out with the thermal load, steam pressure, and nozzle load. The maximum stress location was found to be the riser nozzle bore, and hence fatigue was evaluated at that location, as per ASME Code. As a result, the cumulative usage factor was calculated as 0.00072 (much less than 1). In conclusion, the steam separator was found to be safe from fatigue failure during the expected life.