유한요소법을 이용한 대형 단조품 담금질 과정의 상변태 및 잔류응력 해석

이부윤,조종래 계명대학교 산업기술연구소 1998 産業技術硏究所 論文報告集 Vol.21 No.1

The demands of size and quality of large steel shaft forgings for ship building, power plant, steel plant, etc. are rapidly increasing, and some of these products are manufactured from ingot weighing more than 300 tons. For use as rotating components, shafts require toughness, strength and homogeneity, and therefore they are produced through a variety of heat treatments. According to the increase of ingot size, micro- and macro-segregation and also mass effect of the product increase. Thus, special care should be paid to the heat treatment of such large shaft forgings. In this paper, the heat treatment of large shaft forgings such as rotor and back-up roll is calculated using the commercial finite element code SYSWELD. Calculated distributions of temperature and phase are compared with experimental data. The continuous cooling transformation diagram, thermal and mechenical properties of each phase are used. The phase proportion, hardness and residual stress during water quenching are discussed.

Shape Optimization of Two-Dimensional Thermal Conducting Solid Using Boundary Integral Equation Formulation

Boo Youn Lee,Joo Ho Choi,Byung Man Kwak 대한기계학회 1992 KSME International Journal Vol.6 No.2

Stress Analysis and Evaluation of Steam Separator of Heat Recovery Steam Generator (HRSG)

Boo-Youn Lee(이부윤) 한국기계가공학회 2018 한국기계가공학회지 Vol.17 No.4

Stress of a steam separator, equipment of the high-pressure (HP) evaporator for a HRSG, was analyzed and evaluated according to ASME Boiler & Pressure Vessel Code Section VIII Division 2. First, from the analysis results of the piping system model of the HP evaporator, reaction forces of the riser tubes connected to the steam separator, i.e., nozzle loads, were derived. Next, a finite element model of the steam separator was constructed and analyzed for the design pressure and the nozzle loads. The results show that the maximum stress occurred at the bore of the riser nozzle. The primary membrane stresses at the shell and nozzle were found to be less than the allowable stress. Next, the steam separator was analyzed for the steady-state operating conditions of operating pressure, operating temperature, and nozzle loads. The maximum stress occurred at the bore of the riser nozzle. The primary plus secondary membrane plus bending stress at the shell and nozzle was found to be less than the allowable stress.

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.

OLED 증착용 마스크 프레임의 무게 최소화를 위한 형상최적설계

이부윤(Lee, Boo-Youn) 한국산학기술학회 2013 한국산학기술학회논문지 Vol.14 No.10

본 연구는 FMM 방식을 사용하는 OLED 디스플레이의 증착공정에서 사용되는 마스크 프레임의 무게를 최 소화하기 위한 형상최적설계를 다루었다. 위상최적화 해석을 수행하였으며 그 결과를 토대로 프레임의 가로 및 세로 변에 슬롯을 삽입함으로써 강성을 증가시키면서 무게를 저감시킬 수 있는 설계 개념을 도출하였다. 프레임의 형상설 계변수를 정의하고 형상최적설계 문제를 정립하여 수치적 최적화를 수행하였다. 프레임의 설계기준인 최대 변위의 제 약조건을 만족하면서 무게가 최소인 프레임의 최적형상을 성공적으로 구하였으며, 최적설계된 프레임의 무게는 117.6 kg으로 최초설계안 256 kg 대비 138.4 kg(54.1%)가 감소된 결과를 얻었다. Present work deals with a shape optimal design to minimize the weight of the mask-frame used in the process of OLED vapor deposition by the fine metal mask. A design concept for an optimal shape of the frame to increase the stiffness and to reduce the weight is derived using the topology optimization, shape design variables of the frame by adopting slots being defined. An optimal shape is determined by solving the shape optimization problem to minimize the weight of the frame under constraints of the maximum displacement. Weight of the optimal design is 117.6 kg, which is reduced by 138.4 kg(54.1%) of that of the first design, 256 kg.

캐비닛-도어 통합모델을 이용한 빌트인 양문형 냉장고의 도어 상하단차와 앞뒤단차 해석

이부윤(Boo-Youn Lee) 한국기계가공학회 2018 한국기계가공학회지 Vol.17 No.5

A cabinet-door integrated finite element model was constructed for a built-in side-by-side refrigerator with an ice dispenser, and its deformation was analyzed using the ANSYS finite element software. As loads, the food load needed to fill in the cabinet and doors and the thermal load occurring during normal operation conditions were taken into consideration. The door height difference (DHD) and door flatness difference (DFD) between the two doors of the freezing and refrigerating compartments were derived. The DHD and DFD under the assembled condition without applied loads satisfied the acceptance criteria specified by the refrigerator manufacturer. It appeared that the food load increases the DFD slightly. The thermal load tends to increase the differences because of the thermal deformation, especially the DFD, of the cabinet and doors.

배열회수보일러 고압증발기 튜브군과 헤더의 응력 및 피로수명 평가

이부윤(Boo Youn Lee) 대한기계학회 2018 大韓機械學會論文集A Vol.42 No.12

본 연구는 복합발전플랜트 배열회수보일러의 고압증발기 튜브군과 헤더의 응력 및 피로 평가를 다룬다. 먼저 고압증발기 전체 배관망에 대하여 ASME B31.1을 적용하여 응력을 해석하고 평가하였다. 결과적으로 튜브군의 종방향 응력은 지속하중과 반복하중 하에서 허용기준을 만족하였다. 다음은 ASME Boiler & Pressure Vessel Code, Section VIII, Division 2를 적용하여 대표적 후육부인 출구헤더의 응력과 피로수명을 해석하고 평가하였다. 헤더의 해석 시 노즐과 튜브 단면에는 튜브군 해석결과의 노즐하중을 적용하였다. 설계조건의 해석결과, 헤더의 쉘과 튜브의 국부 1차 막응력은 허용기준을 만족하였다. 과도운전형태를 고려하여 헤더의 열전달해석과 열응력해석을 수행하였으며, 응력집중이 발생한 노즐과 튜브 보어에 대하여 피로수명을 계산한 결과 안전한 것으로 나타났다. This study focused on the evaluation of the stress and fatigue life of the high-pressure evaporator of a heat recovery steam generator (HRSG). First, the piping system was analyzed, and the tube bundles were shown to satisfy the acceptance criteria under sustained and cyclic loads as per ASME B31.1. Next, an outlet header, a representative thick component, was evaluated as per the ASME Boiler and Pressure Vessel Code. In analyzing the header, the nozzle loads resulting from the analysis of the piping system were applied. As a result, the stress of the header under the design condition was found to satisfy the acceptance criteria. Finally, the temperature and thermal stress of the header during the transient operating conditions were analyzed, and the fatigue life at the nozzle and tube bores were evaluated. The header was found to be safe from fatigue failure.

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.

전자레인지 포장품의 클램핑 해석 및 설계

이부윤(Boo Youn Lee),손병삼(Byung Sam Son) Korean Society for Precision Engineering 2009 한국정밀공학회지 Vol.26 No.3