• Journal of Advanced Marine Engineering and Technology
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• 제40권2호
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• pp.146-151
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• 2016

This study concentrates on the design of floater for 15kW-class wave energy converter that extracts the ocean energy by oscillating vertically along the wave motion. The floater connects to a arm structure that connects to a hydraulic cylinder, which drives a hydraulic generator. The study mainly focuses on the structural analysis of the floater. Previous studies have been conducted using a miniature model; however, this study focuses on the size selection of the floater for a full scale model. Static structural analysis is conducted using fine numerical grids. Due to the complexity of the whole model, it is analyzed as a separate component. There are several load cases for each floater size, and they are analyzed thoroughly for stress (von-mises, shear, and normal) and deformation. The initial design was conducted by scaling up from the miniature model of the previous study, and the final design has been redesigned by changing the thickness and internal support structure shape.

• 한국CDE학회논문집
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• 제21권3호
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• pp.234-241
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• 2016

Conventional bent plate used in mandibular reconstruction surgery needs safety verification since its mechanical properties are changed due to the plastic deformation during the bending process. In this study we investigate stability of the plastically deformed plate and the plate with the same shape without plastic deformation through the finite element analysis(FEA). First we simulate the process of plate bending to fit the defect in patient. Then, the other plate is modelled to represent a customized plate with the same shape of the plastically deformed one, but without any residual stresses from plastic deformation. After binding these plates to the mandible, we conduct the masticatory simulation. Finally, we compare the resulting Von Mises stress of the customized plate and of the bent plate. The bent plate shows much higher stress than the customized one due to the residual stresses form the bending process. The study shows that plastic deformation in the plate may decrease the safety of the reconstruction surgery.

• Journal of Advanced Marine Engineering and Technology
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• 제39권8호
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• pp.821-827
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• 2015

This study concentrates on a wave energy converter with floaters that extracts the ocean's energy by moving up and down with the wave motion. The floater is connected to an arm structure, including a hydraulic cylinder that drives a hydraulic generator. This study focuses on a structural analysis of the floater unit, including arm and cylinder components, platform and jack-up system, along with spud columns. Previous studies have been conducted for miniature models for experimentation, but this study focuses on the full-scale model structural analysis. Static structural analysis is conducted using fine numerical grids. Due to the complexity of the whole model, it is analyzed in separate pieces. The floater unit, with arm and cylinder, are combined into one system. The platform is analyzed separately as a single system. There are four jack-up systems for each spud column; only one jack-up system is analyzed, as uniform loads are assumed on each system. There are several load cases for each system, all of which are analyzed thoroughly for stress (von Mises, shear, and normal) and deformation. Acceptable results were obtained for most of the components; unsafe components were redesigned.

• 대한기계학회논문집A
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• 제35권11호
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• pp.1515-1520
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• 2011

본 연구는 유한요소해석에 의해 300톤 골리앗 크레인의 구조해석 및 평가를 하였다. 300톤 골리앗 크레인의 구조는 110m의 스판과 50m의 높이로 구성되어 있다. 크레인은 자중, 크레인의 주행 관성력, 트롤리의 주행 관성력, 풍하중, 지진하중을 받는다. 다양한 하중 조건을 입력하여 크레인의 구조 해석을 수행하였다. 크레인의 등가응력과 전체 변형량을 ANSYS Workbench에서 얻은 결과를 이용하여 크레인의 구조 안전성 여부를 판단하였다.

• 한국자동차공학회논문집
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• 제21권5호
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• pp.157-161
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• 2013

It is well known that the targeted fuel efficiency could only be achieved by more than 40% reduction of the vehicle weight through improved design and extensive utilization of lightweight materials. In order to obtain the goal of the weight reduction of automobiles, the researches about lighter and stronger spring link have been studied without sacrificing the safety of automotive components. In this study, the weight reduction design process of spring link could be proposed based on the variation of von-Mises stress contour by substituting an aluminum alloys (A356) having tensile strength of 245 MPa grade instead of SAPH440 steels. In addition, the effect of the stress and stiffness on shape variations of the spring link were examined and compared carefully. It could be reached that this approach could be well established and be contributed for light-weight design guide and the safe design conditions of the automotive spring link development.

• 전산구조공학
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• 제11권1호
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• pp.161-170
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• 1998

길이가 긴 원통형 실린더를 구성하는 데에 사용될 조인트 부재에 대한 공차설계를 수행하였다. 즉, 원통형 실린더를 체결할 때 사용되는 조인트 부품 가운데 스터드 볼트를 최소 민감도해석에 의해 공차설계를 하였다. 조인트 부재의 공차설계를 위한 최소 민감도 해석에 의한 정식화는 목적함수가 폰 마이세스 응력의 공차에 대한 민감도이고, 여러 부등호 제약식 중에서 자중이 부등호 제안식에 포함된다. 조인트 부재의 경우 자중에 대한 타당한 부등호 제안식을 설정하기 위하여 우선 확정적인 경우에 대한 최적설계를 수행하여 그 범위값을 선정하였다. 원통형 부재의 구조 응답은 축대칭 유한요소로서 구조해석을 수행하여 제안식을 설정하였으며, 직접미분에 의해서 설계 민감도를 구하여 ,최적화 알고리즘과 결합하여 최적의 공차를 제시하였다.

• 한국압력기기공학회 논문집
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• 제13권1호
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• pp.54-60
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• 2017

When a sudden rupture occurs in high energy lines, ejection of inner fluid with high temperature and pressure causes blast wave as well as thrust forces on the ruptured pipe itself. The present study is to examine pipe whip behaviors and blast wave phenomena under postulated pipe break conditions. In this context, typical numerical models were generated by taking a MSL (Main Steam Line) piping, a steam generator and containment building. Subsequently, numerical analyses were carried out by changing break locations; one is pipe whip analyses to assess displacements and stresses of the broken pipe due to the thrust force. The other is blast wave analyses to evaluate the broken pipe due to the blast wave by considering the pipe whip. As a result, the stress value of the steam generator increased by about 7~21% and von Mises stress of steam generator outlet nozzle exceeded the yield strength of the material. In the displacement results, rapid movement of pipe occurred at 0.1 sec due to the blast wave, and the maximum displacement increased by about 2~9%.

• Journal of Periodontal and Implant Science
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• 제45권1호
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• pp.8-13
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• 2015

Purpose: The aim of this study was to evaluate the transfer of different occlusal forces in various skeletal malocclusions using finite element analysis (FEA). Methods: Three representative human cone-beam computed tomography (CBCT) images of three skeletal malocclusions were obtained from the Department of Orthodontics, Yonsei University Dental Hospital, Seoul, South Korea. The CBCT scans were read into the visualization software after separating bones and muscles by uploading the CBCT images into Mimics (Materialise). Two separate three-dimensional (3D) files were exported to visualize the solid morphology of skeletal outlines without considering the inner structures. Individual dental impressions were taken and stone models were scanned with a 3D scanner. These images were integrated and occlusal motions were simulated. Displacement and Von Mises stress were measured at the nodes of the FEA models. The displacement and stress distribution were analyzed. FEA was performed to obtain the 3D deformation of the mandibles under loads of 100, 150, 200, and 225 kg. Results: The distortion in all three skeletal malocclusions was comparable. Greater forces resulted in observing more distortion in FEA. Conclusions: Further studies are warranted to fully evaluate the impact of skeletal malocclusion on masticatory performance using information on muscle attachment and 3D temporomandibular joint movements.

• 한국안전학회지
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• 제28권3호
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• pp.1-5
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• 2013

In order to evaluate fatigue endurance for an MTB(mountain bike) frame, FEM(finite element method) analysis was performed. For evaluating the fatigue endurance of the MTB frame, the S-N data for Al-6061 fillet weldment were compared with the stress analysis results through FEM analysis of the frame. Three loading condition, pedalling, horizontal and vertical loading conditions were considered for fatigue endurance evaluation. Horizontal loading(+1200 N) condition was found to be the most severe to the frame. The maximum von Mises stress of the frame under horizontal loading(+1200 N) condition was determined 294 MPa through FEM analysis of the frame. Conclusively, on the basis of fatigue strength of 200 MPa at the number of cycles of 50,000, the MTB frame has an improper safety factor of approximately 0.25, suggesting that this frame needs reinforcement.

• 한국안전학회지
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• 제26권4호
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• pp.1-6
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• 2011

New methods for joining sheet of metal are being sought. One of the most promising methods is MPJ (mechanical press joining). It has been used in thin metal work because of its simple process and relative advantages over other methods, as it requires no fasteners such as bolts or rivets, consumes less energy than welding, and produces less ecological problems than adhesive methods. In this study, the joining process and static behavior of single overlap joints has been investigated. During fixed die type joining process for SPCC plates, the optimal applied punching force was found. The maximum tensile-shear strength of the specimen produced at the optimal punching force was 1.75 kN. The FEM analysis result on the tensile-shear specimen showed the maximum von-Mises stress of 373 MPa under the applied load of 1.7 kN, which is very close to the maximum tensile strength of the SPCC sheet(= 382 MPa). This suggests that the FEM analysis is capable of predicting the maximum tensile load of the joint.