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유한요소해석을 통한 의료용 리프트 칼럼의 피로수명 예측
천희준,조진래,양희준,이시복,Cheon, Hee-Jun,Cho, Jin-Rae,Yang, Hee-Jun,Lee, Shi-Bok 한국전산구조공학회 2011 한국전산구조공학회논문집 Vol.24 No.3
매우 큰 편심하중을 지지하면서 상하로 수직위치를 제어하는 의료용 리프트 칼럼은 수직위치의 정확도를 확보하기 위해 매우 낮은 구조적 변형과 진동은 물론 높은 피로강도가 요구된다. 리프트 칼럼은 일반적으로 3단 슬라이딩 붐구조로 유도전동기로 작동되며, 상하운동에 따라 변동응력을 나타낸다. 본 연구에서는 리프트 칼럼의 상하운동으로 야기되는 변동응력에 따른 피로강도를 수치해석적으로 예측하였다. 한 주기 상하운동에 따른 응력변동은 유한요소해석으로 구하였으며, 피로수명은 Palmgren-miner기법과 재료의 S-N선도를 적용하여 예측하였다. 수치해석의 신뢰성을 확보하기 위하여 리프트 칼럼의 상세형상과 체결부위을 반영한 3차원 FEM모델을 생성하였으며, 칼럼과 패드사이 계면은 접촉조건으로 처리하였다. Medical lift column controlling the vertical position while supporting heavy eccentric load should have the high fatigue strength as well as the extremely low structural deflection and vibration in order to maintain the positioning accuracy. The lift column driven by a induction motor is generally in a three-step sliding boom structure and exhibits the time-varying stress distribution according to the up-and-down motion. This study is concerned with the numerical prediction of the fatigue strength of the lift column subject to the time-varying stress caused by the up-and-down motion. The stress variation during a motion cycle is obtained by finite element analysis and the fatigue life is predicted making use of Palmgren-miner's rule and S-N curves. In order to secure the numerical analysis reliability, a 3-D FEM, model in which the detailed lift column structure and the fitting parts are fully considered, is generated and the interfaces between lift column and pads are treated by the contact condition.
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모바일하버용 컨테이너 자동 하역 장치의 레일-이탈 방지 모듈 설계
천희준(Heejun Chun),이재훈(Jae-Hoon Lee),이재철(Jaecheol Lee),박성훈(Seonghun Park) (사)한국CDE학회 2010 한국 CAD/CAM 학회 학술발표회 논문집 Vol.2010 No.1
An automated container-stacking system(ACSS) for Mobile Harbor functions to arrange and stack containers loaded to Mobile Harbor from a container ship through the main crane of Mobile Harbor. The current paper focuses on the design of an anti-derail module in the ACSS of Mobile Harbor, and the anti-derail module consists of three driving components and an anti-derail component. Finite element analysis (FEA) of three driving components exhibited that the largest von Mises stresses occurred around the connecting hole between the three components of the anti-derail module. The values of maximum von Mises stresses for the three main components were 210MPa, 165MPa, 78MPa, respectively, which were lower than the allowable stress of a SM490Y material (243MPa). The allowable stress was computed from the yield stress of a SM490Y material (365MPa) divided by a factor of safety (1.5). Future plan is to change the design of this component to decrease the maximum stress less than the allowable stress, and further to perform FEA by considering the maximum dynamic load applied to the anti-derail device.
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모바일하버용 컨테이너 자동 하역 장치의 프레임 모듈 구조 설계
이재훈(Jae-Hoon Lee),이재철(Jaecheol Lee),천희준(Heejun Chun),박성훈(Seonghun Park) (사)한국CDE학회 2010 한국 CAD/CAM 학회 학술발표회 논문집 Vol.2010 No.1
It is very important to stack containers at any desired locations with a high speed in order to increase the dynamic stability of mobile harbor (MH) as well as to increase the efficiency of operating (i.e., loading, unloading and stacking) time of containers. Therefore, the purpose of the current study is to design a frame module of an automated container-stacking system (ACSS) for mobile harbor which should have functions to automatically arrange and stack containers loaded to mobile harbor from a container ship. Design of a frame module for the ACSS was constructed by beam elements and validated by the calculation of the deflections and stresses of the frame module using Finite Element Method (FEM) under the loading conditions of the frame masses, the container mass and the wire initial tension. All frames in the frame module exhibited lower stresses than the allowable stress of a SM490Y material (243 MPa) which was used as a material of a frame module, and the allowable stress of SM490Y was computed from the yield stress of a SM490Y material (365 MPa) divided by a factor of safety (1.5). Regarding design of the frame module, the deflection of a frame of 30 m, which cross over the ACSS laterally, is the most important design specification to be considered, and the FEM results showed that the deflection of this frame (25.3 mm) was less than the allowable deflection (50 mm) calculated by the length (30m) of the frame divided by 600.
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모바일하버용 컨테이너 자동 하역 장치의 컨테이너 운송 모듈 구조 설계
이재철(Jaecheol Lee),이재훈(Jae-Hoon Lee),천희준(Heejun Chun),박성훈(Seonghun Park) (사)한국CDE학회 2010 한국 CAD/CAM 학회 학술발표회 논문집 Vol.2010 No.1
The objective of this study is to design a container transport module in the automated container-stacking system (ACSS) for Mobile Harbor (MH). The container transport module is designed to perform automated locking and unlocking of the landed containers on the module through an automated twist-lock as well as automated adjustments of the twist-lock to the variable sizes of containers, and further perform to move to the location of a spreader. Finite Element Method (FEM) of the designed container transport module showed that the largest von Mises stress was produced in the end of the container transport module with a value of 137MPa, and satisfied the allowable stress of a SM490Y material (243MPa) which was computed from the yield stress of a SM490Y material (365MPa) divided by a factor of safety (1.5). FEM results showed that the deflection of this module (7.4mm) was less than the allowable deflection (23mm) calculated by the length (12m) of the module divided by 600.
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