기능경사 소재 등가 물성치 예측을 위한 균질화 기법의 특성분석을 위한 수치해석

조진래,최주형,신대섭,Cho, Jin-Rae,Choi, Joo-Hyoung,Shin, Dae-Sub 한국전산구조공학회 2008 한국전산구조공학회논문집 Vol.21 No.1

기능경사 소재(FGM)에는 서로 다른 두 가지 구성입자들이 혼합되어 있는 경사층(graded layer)이 삽입되어, 소재 전 영역에 걸쳐 구성입자의 체적분율이 연속적이고 기능적으로 변화하도록 되어있다. 이러한 이상(dual-phase) 입자복합재의 열 기계적 거동을 해석함에 있어 필수적인 경사층의 물성치는 전통적으로 균질화 기법을 이용하여 예측되었다. 하지만, 이러한 균질화 기법은 구성입자의 형태, 분산구조 등과 같은 상세 형상을 반영하지 못하지 때문에 복합재의 총체적인 등가 물성치 예측에만 국한 되어왔다. 이러한 맥락에서 본 연구에서는 경사층을 미시역학적으로 이산화 모델링하고, 다양한 체적분율과 외부 하중조건에 대해 유한요소해석을 실시하여 이러한 균질화 기법들의 특성을 분석하였다. Graded layers in which two different constituent particles are mixed are inserted into functionally graded material such that the volume fractions of constituent particles vary continuously and functionally over the entire material domain. The material properties of this dual-phase graded region, which is essential for the numerical analysis of the thermo-mechanical behavior of FGM, have been predicted by traditional homogenization methods. But, these methods are limited to predict the global equivalent material properties of FGMs because the detailed geometry information such as the particel shape and the dispersion structure is not considered. In this context, this study intends to investigate the characteristics of these homogenization methods through the finite element analysis utilizing the discrete micromechanics models of the graded layer, for various volume fractions and external loading conditions.

선박용 엔진 프레임 박스의 구조해석을 위한 기구학적 분석

이재훈,최종호,조진래,이인수,Lee, Jae-Hoon,Choi, Jong-Ho,Cho, Jin-Rae,Lee, In-Soo 한국전산구조공학회 2007 한국전산구조공학회논문집 Vol.20 No.5

본 논문에서는 S60MC-C 선박용 다실린더 엔진의 구조해석을 위한 기구학적인 분석에 대해 서술하였다. 구조해석을 위해 프레임박스에 작용하는 측력과 크랭크 저널베어링에 작용하는 반력이 필요하다. 각각의 동적인 작용력을 구하기 위해, 선박용 엔진 내부의 구동부를 마찰이 없는 평판의 운동으로 가정하고, 단실린더에 대해 동역학적인 평형관계를 이용하여 엔진 구동시의 크랭크 각도별 작용력을 구하였다. 단실린더에서의 하중조건을 바탕으로 특정 시점에서 각각의 실린더에 작용하는 하중을 구하기 위해 크랭크암의 각도의 차이를 이용하였다. 구조해석을 위해 프레임박스의 응력 변화에 큰 영향을 줄 것으로 판단되는 8개의 각도를 선정하였다. This paper addresses the kinematic study for the structural analysis of the S60ME-C multi-cylinder vessel engine. The load conditions such as the lateral force and the reaction force by the crank-shaft are required for the FEM analysis. The driving parts in vessel engine are assumed to be in frictionless rigid plane motion. We analytically derive dynamic forces for a single cylinder by using the dynamic force equilibrium. But, for the structural analysis for a single cylinder block, we use the loading conditions of two neighboring cylinders. Meanwhile, we use the single cylinder's loading condition to calculate the multi-cylinder's loading conditions, because each cylinder shows a cyclic loading pattern with respect to the crank arm's rotation angle.

유한요소 해석을 이용한 선박용 엔진 프레임 박스 용접부의 피로수명 예측

이재훈,최종호,조진래,이인수,Lee, Jae-Hoon,Choi, Jong-Ho,Cho, Jin-Rae,Lee, In-Soo 한국전산구조공학회 2007 한국전산구조공학회논문집 Vol.20 No.5

본 논문은 선박용 엔진인 S60MC-C의 프레임 박스 용접부에 대한 피로수명 예측을 위한 수치적 기법을 제시한다. 피로 수명 평가를 위해 싸이클 동안의 동적인 응력변화를 계산해내야 하며, 이에 따라 선행된 연구에서 얻은 엔진의 한 싸이클 동안의 하중 조건으로 상용 유한요소해석 프로그램을 이용한 구조해석을 실시하였다. 구조해석은 8단계에 대해 이루어 졌으며, 그 결과를 바탕으로 프레임 박스 용접부의 피로수명 평가를 위해서 HSS(Hot spot stress), Reservoir counting method, Palmgren-miner's rule을 적용하였다. 결과적으로 구조해석을 통한 대상 엔진의 취약부와 과잉 설계부를 확인하였고, 피로수명의 평가를 통해 설계의 적절성 여부를 평가하였다. This paper presents the numerical estimation of the fatigue life for the frame box's welded parts of the marine vessel engine S60MC-C. The time-variations of the effective stresses at the critical points during a piston cycle are computed through the finite element analysis, by applying the dynamic loadings that were analytically derived in the previous paper. The fatigue lives of the welded parts are estimated by making use of the hot-spot stress extrapolation and the Palmgren-miner cumulative damage rule.

타이어 롤링해석을 활용한 타이어마모량 예측에 관한 연구

최주형(Joo-Hyoung Choi),조진래(Jin-Rae Cho),김기전(Gi-Jeon Kim),우종식(Jong-Shik Woo) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.11

Tire wear of automobile is considered as an important factor to decrease the breaking and cornering performance. However, the tire rubber materials have been developed on an empirical basis up to the present time. Furthermore, one of the most expensive tests is the highway abrasion test. In this aspect, the numerical simulation approach is currently being widely employed. In this paper, we investigated the factors affecting the tire wear based on the mechanism of abrasive wear, and we found that the tire wear is closely related to frictional energy. Accordingly, the frictional energy is computed by utilizing the 3D dynamic rolling analysis of patterned tire. Finally, the amount of tire wear is predicted by correlating frictional energy with the wear equation.

기능경사 복합소재의 Global-Local 해석기법에 관한 연구

최주형(Joo-Hyoung Choi),조진래(Jin-Rae Cho) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.6

Most of the previous studies of FGMs have focused on the influence of the volume fraction distribution in the global sense. But, the response of phase materials in reality relies on the shape and size, the orientation and dispersion structure of constituents. Therefore, the modeling in the microstructure scopic level is essential for the accurate analysis of FGM. However, it requires too many degrees of freedom and the cost of computation. In this paper, we present a global-local analysis technique to predict the detailed stress state within the specific local region in FGM. The numerical experiments are carried out by considering the shape and the dispersion structure of Ni-Al₂O₃ FGM to illustrate the proposed technique.

유한요소법을 이용한 Weather Strip 압출성형공정의 Parametric 해석

최종호(Jong-Ho Choi),조진래(Jin-Rae Cho),김준형(Joon-Hyung Kim) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.4

Rubber material is used in weather-strip extrusion forming process. Rubber material is macromolecule material and shows characteristics such shear thinning fluid. The dynamic viscosity of this fluid is influenced by temperature and shear strain rate. In this paper, the dynamic viscosity function is derived by Power-law model as non-Newtonian fluid model with effect of temperature and shear strain rate. Also, we observe the effect of extrusion under controling flow velocity of row material and temperature from parametric analysis. The numerical results will overcome the conventional try-error method that has been adopted for the process analysis and design.

단위입자 형상에 따른 하이브리드 기능소재의 역학적 특성해석

최주형(Joo-Hyoung Choi),조진래(Jin-Rae Cho) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.10

Traditional homogenization methods are limited to predict the equivalent material properties of FGMs because the detailed geometry information such as the particle shape and the dispersion structure is not considered. Accordingly, unit cell analysis based on superposition method were performed to obtain the equivalent material properties of hybrid functionally graded material. Hybrid functionally graded material with reinforcement of rectangle and triangle shape was modeled by unit cells. In this paper, the effects of various volume fractions, reinforcement shapes and angles on the mechanical behavior are studied numerically for hybrid graded materials.

코트 스포츠화의 착지충격 평가를 위한 유한요소 해석

김성호(Seong-Ho Kim),조진래(Jin-Rae Cho),류성헌(Sung-Heon Ryu),최주형(Joo-Hyung Choi) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.4

Court sport shoes is consisted of several functional parts such as soles, upper and midfoot reinforcements. Currently, intensive research for court sport shoes considering functional parts is in progress world widely, but the shoes design relies only on the view point of kinesilogy and biomechanics until now. Thus, more scientific and reliable evaluation of shoes characteristics is definitely required. In this paper, we evaluate the landing impact of court sport shoes by using finite element method. We construct a shoes-leg coupled FEM model which can simulate effectively impact in running mode. From the numerical analysis results, the designer can establish the advanced design concepts and build up the detailed design standard for the specific court sport shoes under consideration.

유한요소 해석을 통한 코트 스포츠화의 런닝시 충격력 평가

김성호(Seong-Ho Kim),조진래(Jin-Rae Cho),류성헌(Sung-Heon Ryu),최주형(Joo-Hyung Choi) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.11

A fundamental function of court sport shoes has been considered as the protection of human feet from unexpected injuries. But, recently its role for improving the playing competency is being regarded as a more important function. In connection with this situation, intensive efforts are being world-widely forced on the development of court sport shoes proving the excellent playing competency, by taking kinesiology and biomechanics into consideration. However, the success of this goal depends definitely on the shoes design based upon the reliable evaluation of shoes functional parts. This paper addresses the application of finite element method to the evaluation of landing impact force of court sport shoes. In order to reflect the coupling effect between leg and shoes accurately and effectively, we construct a fully coupled shoes-leg FEM model which does not rely on the independent experimental data any more. Through the numerical experiments, we assess the reliability of the coupled FEM model by comparing with the experimental results and investigate the landing impact characteristics of court sport shoes.

해상상태 3의 파고에 따른 모바일 하버 크레인의 롤링 동응답 해석

한기철,황순옥,최은호,조진래,임오강,Han, Ki-Chul,Hwang, Soon-Wook,Choi, Eun-Ho,Cho, Jin-Rae,Lim, O-Kaung 한국전산구조공학회 2010 한국전산구조공학회논문집 Vol.23 No.5

해상부유식 항만부두인 모바일 하버에는 일반 지상설치식 크레인과는 다른 구조를 가진 크레인이 설치되어 있다. 그리고 상부에 설치되어 있는 크레인은 파고에 따른 모바일 하버 전체의 동적 안정성에 지대한 영향을 미친다. 본 연구는 해상상태 3의 파고에 따른 모바일 하버용 크레인의 롤링 동응답 해석에 관한 내용으로서, 이론과 수치해석 기법으로 구성된 2단계 해석절차를 적용하였다. 선형파고이론에 따라 강체로 가정한 모바일 하버의 롤링응답을 이론적으로 계산하고, 모바일하버 본체의 롤링에 따른 탄성체 크레인의 롤링 동특성을 유한요소해석으로 분석하였다. 모바일 하버 본체와 직접 접하는 파고의 동적 연계효과는 부가질량 기법으로 반영하였다. In the sea-floating logistics port called mobile harbor a crane system with the different structure from the conventional above-ground container crane is installed. And, the dynamic stability of whole mobile harbor by the wave excitation is definitely affected by the crane positioned at the top. This paper is concerned with the dynamic rolling analysis of the mobile harbor subject to sea state 3 wave excitation, for which two-step analysis procedure composed of theoretical and numerical approaches is employed. First, the rigid rolling of mobile harbor is obtained according to the linear wave theory. And then, the dynamic rolling response of the flexible crane system caused by the rolling excitation of mobile harbor is analyzed by finite element analysis. The coupled interaction effect between the sea wave and the mobile harbor is taken into consideration by the added mass technique.