• 한국산학기술학회논문지
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• 제6권1호
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• pp.83-86
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• 2005

본 연구에서는 절삭 가공시 공구가 받는 절삭력과 칩-공구 사이에서 발생하는 절삭온도에 의한 공구의 변형을 예측하였다. 3D CAD를 이용하여 공구를 모델링 하였으며 절삭력과 절삭온도를 하중조건으로 부여하여 유한요소해석을 수행하였다. 하중조건으로 사용한 절삭력과 절삭온도는 절삭이론을 이용한 절삭력 모델을 사용하여 예측하였으며 실험을 통해 모델의 타당성을 검증하였다. 그러므로 본 연구는 절삭조건과 재료 물성치 그리고 공구 형상만을 알면 이에 따른 절삭력 성분 및 절삭온도 둥을 얻을 수 있고, 이를 이용하여 절삭 가공시 발생하는 공구의 변형을 예측할 수 있다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.198-203
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• 2004

In these days, the orthodontic surgery including lingual orthodontics has attracted a person' attention due to its functional and esthetic appreciation. The delivery of the optimal orthodontic treatment is greatly influenced by clinician' ability to predict and control the tooth movement by applying force system to dentition. The skeletal anchorage system with the miniscrew has been used recently in the lingual orthodontics to assist the anchorage control. Precise understanding of the force system produced from the various orthodontic appliances is necessary. However, the qualitative and quantitative effect of the miniscrew has not been identified well. In this paper, three dimensional finite element analysis is introduced on the lingual orthodontics to investigate the effect of anterior retraction force on the miniscrew and transpalatal arch wire. The purpose of this study is to determine the location of the miniscrew and the point of force application of the anchorage system in the lingual orthodontics. The analysis results indicate the efficient position of the miniscrew and the transpalatal arch wire in the lingual orthodontics.

• 한국산학기술학회논문지
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• 제8권6호
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• pp.1319-1324
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• 2007

입출력 헤드 구조의 형상을 정확하게 조절할 수 있는 기술은 하드디스크 드라이브의 성능에 결정적인 요소이다. 본 논문에서 연구한 슬라이더는 알루미나 티타늄 카아바이드로 구성되었으며 디스크를 통과할 때 공기 베어링 역할을 한다. 그러므로 슬라이더의 곡률을 조절하는 것은 매우 중요하다. 본 연구에서 곡률을 조절하기 위해 헤드 슬라이더에 잔류응력을 발생시켜 곡률을 생성하는 레이저 화선 시스템이 사용된다. 슬라이더 형상의 조절을 강화하기 위해 화선(scribe)의 형상에 따른 곡률을 예측할 수 있는 방법이 중요하다. 레이저 화선과 유사한 효과를 얻을 수 있는 응력을 발생하는 하중계를 유한요소 모델에 적용한다. 하중계에 의해 형성된 곡률은 측정값을 통해 보정된다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.519-520
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• 2006

The aim of this study was biomechanical analysis of shelf operation in patients with dysplastic hip joint by finite element contact analysis. Two dimensional CT images were used to construct the finite element models to analyze the contact pressure, and the 3D expansion of the Ninomiya's method was used in the calculation of the resultant force in the hip joint. The surgery recovered the center-edge angles to the normal anatomical range and increased the contact areas in two patients. The maximum contact pressures and von-mises stresses were decreased. The present study provides the biomechanical guideline of optimal surgical parameters to maximize the surgical efficiency and the clinical outcomes in dysplastic hip joint using the shelf operation.

• 한국정밀공학회지
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• 제12권9호
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• pp.148-155
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• 1995

The object of this study is to achieve a gteater understanding of meterial removal process and its mechanism. In this study, some applications of finite element techniques are applied to analyze the chip formation and cutting heat generation mechanism of metal cutting. To know the effect of cutting parameters, simulations employed some independent cutting variables change, such as constitutive deformation laws of workpiece and tool material, frictional coefficients and tool-chip contact interfaces, cutting speed, tool rake angles, depth of cut and this simulations also include large elastic-plastic defor- mation, adiabetic thermal analysis. Under a usual plane strain assumption, quasi-static, thermal-mechanical coupling analysis generate detailed informations about chip formation process and cutting heat generation mechanism Some cutting parameters are affected to cutting force, plastic deformation of chip, shear plane angle, chip thickness and tool-chip contact length and reaction force on tool, cutting temperature and thermal behavior. Several aspects of the metal cutting process predicted by the finite element analysis provide information about tool shape design and optimal cutting conditions.

• Journal of Advanced Research in Ocean Engineering
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• 제4권1호
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• pp.25-34
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• 2018

In this study, the behavior of the coupled mooring system and floating body is analyzed. The related works are introduced for the mooring analysis of the floating body. Equations motion are introduced for calculating mooring force connected with the floating body. For formulating the equations of motion, the concept of the constrained force is applied for compact expression of it. The input and output data of the module for calculating mooring force is defined. The static analysis and quasi-static analysis are performed. For the analysis, equilibrium equation for elastic catenary mooring line is used by employing finite element method, and the C# solver is developed in this research. The analysis results are validated by comparing with other research results.

• Journal of Mechanical Science and Technology
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• 제16권12호
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• pp.1687-1692
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• 2002

The problem analyzed here is a sheet metal forming process which requires a drawbead. The drawbead provides the sheet metal enough tension to be deformed plastically along the punch face and consequently, ensures a proper shape of final products by fixing the sheet to the die. Therefore, the optimum design of drawbead is indispensable in obtaining the desired formability. A static-explicit finite element analysis is carried out to provide a perspective tool for designing the drawbead. The finite element formulation is constructed from static equilibrium equation and takes into account the boundary condition that involves a proper contact condition. The deformation behavior of sheet material is formulated by the elastic-plastic constitutive equation. The finite element formulation has been solved based on an existing method that is called the static-explicit method. The main features of the static-explicit method are first that there is no convergence problem. Second, the problem of contact and friction is easily solved by application of very small time interval. During the analysis of drawbead processes, the strain distribution and the drawing force on drawbead can be analyzed. And the effects of bead shape and number of beads on sheet forming processes were investigated. The results of the static explicit analysis of drawbead processes show no convergence problem and comparatively accurate results even though severe high geometric and contact-friction nonlinearity. Moreover, the computational results of a static-explicit finite element analysis can supply very valuable information for designing the drawbead process in which the defects of final sheet product can be removed.

• Structural Engineering and Mechanics
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• 제80권5호
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• pp.503-522
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• 2021

This paper investigates experimentally and numerically the influence of drilling process on the mechanical and thermomechanical behaviors of woven glass fiber reinforced polymer (GFRP) composite plate. Through the experimental analysis, a CNC machine with cemented carbide drill (point angles 𝜙=118° and 6 mm diameter) was used to drill a woven GFRP laminated squared plate with a length of 36.6 mm and different thicknesses. A produced temperature during drilling "heat affected zone (HAZ)" was measured by two different procedures using thermal IR camera and thermocouples. A thrust force and cutting torque were measured by a Kistler 9272 dynamometer. The delamination factors were evaluated by the image processing technique. Finite element model (FEM) has been developed by using LS-Dyna to simulate the drilling processing and validate the thrust force and torque with those obtained by experimental technique. It is found that, the present finite element model has the capability to predict the force and torque efficiently at various drilling conditions. Numerical parametric analysis is presented to illustrate the influences of the speeding up, coefficient of friction, element type, and mass scaling effects on the calculated thrust force, torque and calculation's cost. It is found that, the cutting time can be adjusted by drilling parameters (feed, speed, and specimen thickness) to control the induced temperature and thus, the force, torque and delamination factor in drilling GFRP composites. The delamination of woven GFRP is accompanied with edge chipping, spalling, and uncut fibers.

• The Journal of the Acoustical Society of Korea
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• 제15권4E호
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• pp.37-44
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• 1996

To get accurate vibration analysis of rotor-bearing systems, finite element models of high speed rotating shaft, unbalance disk, and fluid film journal bearing are developed. The study includes the effects of rotary inertia, gyroscopic moment, damping, shear deformation, and axial torque in the same model. It does not include the axial force effect, but the extension is straighforward. The finite elements developed can be used in the analysis design of any type of multiple rotor bearing system. To show the accuracy of the models, numerical examples are demonstrated.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2009년도 추계학술대회 논문집
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• pp.470-473
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• 2009

In this paper, back pressure forging processes of which back pressures are exerted by mechanical forces including spring reaction are simulated by three-dimensional finite element method. The basic three-dimensional approach extended from two-dimensional approach is accounted for. An axisymmetric backward and forward extrusion process having a back pressing die, which is exposed to oscillation of forming load due to variation of reduction ratios with stroke and its related frequent variation of major deforming region, is simulated by both two and three dimensional approaches to justify the presented approach by their comparison. A three-dimensional forging process having a back pressing die attached to the punch by a mechanical spring is simulated and the results are investigated to reveal accuracy of the presented approach.