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정성필(Sung Pil Jung),박태원(Tae Won Park),조재익(Jae Ik Cho),정기범(Gi Beom Jeong),정원선(Won Sun Chung) 한국자동차공학회 2010 한국자동차공학회 부문종합 학술대회 Vol.2010 No.5
In this study, a transient FE analysis method was used to analyze the fully coupled thermo-mechanical problem for a disc brake system. Mechanical and thermal model for the disc brake were generated separately, and solved iteratively. Three dimensional FE model of a disc brake was created. The mechanical model of the disc brake was assumed to be in braking with an acceleration of 0.3g from 1400 rpm to 700 rpm. The thermal model with an initial temperature of 80℃ interacts with the mechanical model, and the friction heat between the pad and disc is generated by the friction contact condition. Due to the heat generation, the material of disc is expanded and alters the contact condition.
유한 요소법을 이용한 자동차용 디스크 브레이크의 열간 저더 해석
정성필(Sung Pil Jung),박태원(Tae Won Park),정원선(Won Sun Chung) 대한기계학회 2011 大韓機械學會論文集A Vol.35 No.4
차량 제동시 디스크와 패드사이의 미끄럼 접촉에 의해 발생하는 마찰열은 재질의 열 탄성 변형을 일으키고, 이는 접촉면의 압력 분포에 영향을 끼친다. 이러한 열탄성 불안정성 (Thermo-Elastic Instability, TEI)은 디스크의 고유 진동모드와 결합되어 열섬 현상 및 열간 저더 진동을 발생시킨다. 본 연구에서는 상용 유한 요소 해석 프로그램인 SAMCEF 를 이용하여 자동차용 통풍식 디스크에 대한 3 차원 열간 저더 해석을 수행하였다. Staggered approach 에 의거한 중간 처리기를 이용하여 구조-동역학 해석 결과와 열 전달 해석 결과를 교환하였다. 디스크 표면에 열섬이 발생하는 것을 확인하였고, 이를 디스크 고유 진동 모드와 비교함으로써 모드 형상과 열섬 분포의 관계를 분석하였다. Thermal energy generated because of the friction between the disc and pad is transferred to both sides and causes thermal expansion of the material, which affects the contact pressure distribution. This phenomenon, which is called thermoelastic instability (TEI), is affected by the natural mode of a disc. TEI results in the formation of a hot spot and causes hot judder vibrations. In this study, three-dimensional analysis of the hot judder of a ventilated disc for automotives was performed by using the commercial finite element analysis program, SAMCEF. The intermediate processor based on a staggered approach was used to exchange the result data of the mechanical and thermal model. The hot spot was formed on the surface of the disc, and the number of hot spots was compared with the natural mode of the disc.
MATLAB 을 이용한 유연 다물체 시스템의 해석 및 제어
정성필(Sung Pil Jung),박태원(Tae Won Park) 대한기계학회 2008 大韓機械學會論文集A Vol.32 No.5
In this paper, analysis and control of the flexible multibody system using MATLAB is presented. The equations of motion of a flexible body are derived in terms of the modal coordinate. The rigid-flexible multibody dynamic solver is developed. Finite element information required to analyze motion of flexible bodies is imported from ANSYS. The modified finite element data, such as modal mass matrix, modal stiffness matrix and constraint mode shapes, is calculated in the solver. Since the solver is developed using MATLAB, it is very easy to connect with SIMULINK which is widely used to control motion of the multibody system. Several simulations are implemented to verify the developed solver. A control example is carried out and the usefulness of the developed solver is demonstrated.
정성필(Sung Pil Jung),박태원(Tae Won Park),정원선(Won Sun Cheong) 대한기계학회 2010 大韓機械學會論文集A Vol.34 No.2
본 논문에서는 플랫 타입 블레이드를 장착한 와이퍼 시스템의 성능을 예측하기 위한 동역학 해석방법을 제시하였다. 고무 재질로 이루어진 블레이드는 비선형의 특성을 갖기 때문에, 블레이드의 동적 특성을 나타내기 위하여 모달 좌표계와 절대 절점 좌표계를 이용하였다. 블레이드 단면의 굽힘 특성을 파악하기 위해 블레이드에 대한 구조 해석을 실시하였다. 해석 결과에 따라 블레이드 단면을 강체, 유연체 및 대변형체의 3 부분으로 구분하였다. 모달 좌표계와 절대 절점 좌표계를 이용하여 블레이드 단면의 유연체 및 대변형체를 표현하였다. 동역학 해석 결과를 검증하기 위해 실험을 실시하였고, 결과비교를 통해 본 연구에서 생성한 블레이드에 대한 유연 다물체 모델의 신뢰성을 검증하였다. This paper presents the dynamic analysis method for estimating the performance of flat-type blades in wiper systems. The blade has nonlinear characteristics since the rubber is a hyper-elastic material. Thus, modal coordinate and absolute nodal coordinate formulations were used to describe the dynamic characteristic of the blade. The blade was structurally analyzed to find the bending characteristics of the cross section of the blade. According to the analysis results, the blade section is divided into three deformation bodies: rigid, small, and large. For the small deformation body, the modal coordinate formulation is used, while the absolute nodal coordinate formulation is used for the large deformation body. To verify the dynamic analysis result, an experiment was performed. The simulation and experiment results were compared to verify the flexible multi-body dynamic model.