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Structural Damping Effects on Stability of a Cantilever Column under Sub-tangentially Follower Force
Dong-Ju Min(민동주),Jae-gyun Park(박재균),Moon-Young Kim(김문영) 한국소음진동공학회 2016 한국소음진동공학회 논문집 Vol.26 No.6
A stability theory of a damped cantilever column under sub-tangential follower forces is first summarized based on the stability map. It is then demonstrated that internal and external damping can be exactly transformed to Rayleigh damping so that the damping coefficients can be effectively determined using proportional damping. Particularly a parametric study with variation of damping coefficients is performed in association with flutter loads of Beck’s column and it is shown that two damping coefficients can be correctly estimated for real systems under the assumption of Rayleigh damping. Finally a frequency equation of a cantilever beam subjected to both a sub-tangentially follower force and two kinds of damping forces is presented in the closed-form and its stability maps are constructed and compared with FE solutions in the practical range of damping coefficients.
민동주(Dong-Ju Min),정명락(Myung-Rag Jung),박성민(Sung-Min Park),김문영(Moon-Young Kim) 한국소음진동공학회 2015 한국소음진동공학회 학술대회논문집 Vol.2015 No.10
The purpose of this study is to investigate the influence of moving mass on the vibration characteristics and the dynamic response of the simply supported beam. The three types of the moving mass (moving load, unsprung mass, and sprung mass) are applied to the vehicle-bridge interaction analysis. And the numerical analyses are then conducted to evaluate the effect of the unsprung mass and the spring and damper of the sprung mass on natural frequencies and dynamic responses of the simple beam. Particularly, in the case of the sprung mass, how the natural frequency of the interaction system is varied is explored depending on the position of the moving mass and the frequency ratio of the moving mass and the beam. Finally the parametric study on the resonance phenomena is done with changing mass, spring and damper parameters through the time history simulation.
Structural Damping Effects on Stability of a Cantilever Column under Sub-tangentially Follower Force
Dong-Ju Min(민동주),Jae-gyun Park(박재균),Moon-Young Kim(김문영) 한국소음진동공학회 2016 한국소음진동공학회 학술대회논문집 Vol.2016 No.4
A stability theory of a damped cantilever column under sub-tangential follower forces is first summarized based on the stability map. It is then demonstrated that internal and external damping can be exactly transformed to Rayleigh damping so that the damping coefficients can be effectively determined using proportional damping. Particularly a parametric study with variation of damping coefficients is performed in association with flutter loads of Beck column and it is shown that two damping coefficients can be correctly estimated for real systems under the assumption of Rayleigh damping. Finally a frequency equation of a cantilever beam subjected to both a sub-tangentially follower force and two kinds of damping forces is presented in the closed-form and its stability maps are constructed and compared with FE solutions in the practical range of damping coefficients.
레일-윤축 사이의 궤도력을 고려한 열차-교량 동적상호작용해석
민동주(Dong-Ju Min),곽종원(Jong-Won Kwark),김문영(Moon-Young Kim) 한국철도학회 2014 한국철도학회 학술발표대회논문집 Vol.2014 No.10
열차-교량 동적상호작용해석에 있어 궤도구조의 상호작용력을 고려하는 방법은 크게 3가지로 분류할 수 있다. 첫번째로 레일-윤축 사이를 압축스프링으로 이상화하여 스프링력의 상호작용을 고려하는 해석법이며, 두번째로 바퀴-레일 사이가 항상 접촉하고 있다는 가정하에 적용되는 모델로 바퀴와 그 지점의 레일의 변위를 일치시키는 해석법이다. 마지막으로 레일-윤축 사이의 contact mechanism을 보다 사실적으로 고려하는 해석법이다. 즉, 바퀴-레일 사이의 접촉면적, 압축변형을 산정하여 압축변형이 발생할 경우 압축스프링과 유사한 개념으로 가정하고, 바퀴-레일 사이의 상대변위가 음인 경우는 분리가 발생하는 것을 허용하며, 횡방향으로 플랜지 접촉력을 고려하는 비선형 반복해석법이다. 본 논문에서는 언급한 해석법을 기술하고, 해석예를 통해 해석결과를 비교 분석한다. There are representative 3 types for considering interaction forces between wheel-rail in trainbridge interaction analysis. One is a spring model that idealizes interaction forces between wheel-rail as a spring. And the other one is a non-jump model that assumed coincidence of wheel and rail responses at the same position. The last one is a contact model that considers contact mechanism between wheel-rail to analyze the train-bridge interaction more realistically. In this study, above mentioned 3 types models are described briefly, and an accurate contact model including jump phenomena and flange contact motions is then presented and analyzed. Lastly, the results for 3 types are compared under the same condition.
이동질량을 고려한 단순지지된 교량의 진동수 및 공진현상 분석
민동주(Dong-Ju Min),정명락(Myung-Rag Jung),박성민(Sung-Min Park),김문영(Moon-Young Kim) 한국소음진동공학회 2016 한국소음진동공학회 논문집 Vol.26 No.1
The purpose of this study is to investigate the influence of moving mass on the vibration characteristics and the dynamic response of the simply supported beam. The three types of the moving mass(moving load, unsprung mass, and sprung mass) are applied to the vehicle-bridge interaction analysis. The numerical analyses are then conducted to evaluate the effect of the mass, spring and damper properties of the moving mass on natural frequencies and dynamic responses of the simply supported beam. Particularly, in the case of the sprung mass, variations of the natural frequency of simply supported beam are explored depending on the position of the moving mass and the frequency ratio of the moving mass and the beam. Finally the parametric studies on the resonance phenomena are performed with changing mass, spring and damper parameters through the dynamic interaction analyses.
자기부상열차의 모델링방법에 따른 열차-교량의 동적상호작용 해석
정명락,민동주,이준석,권순덕,김문영,Jung, Myung-Rag,Min, Dong-Ju,Lee, Jun-Seok,Kwon, Soon-Duck,Kim, Moon-Young 한국전산구조공학회 2011 한국전산구조공학회논문집 Vol.24 No.2
본 연구에서는 속도의 변화 그리고 모델링방법이 자기부상열차의 주행성에 미치는 영향을 파악하는데 목적을 두고 있다. 이를 위하여 2000:1의 처짐비를 가지는 동일한 교량 위를 속도를 변화시키면서(100km/h에서 700km/h까지 100km/h간격으로) 6가지 모델의 자기부상열차를 주행시키기 위하여 4자유도 6자유도 10자유도 차량에 대한 운동방정식을 구성하고 4계 룬지쿠타법을 적용하여 수치해석을 수행한다. 해석결과를 보면 속도가 낮을수록 보기 및 EMS의 개수가 많은 모델일 수록 자기부상열차의 주행성이 향상됨을 알 수 있다. The purpose of this study is to examine the impact that change in speed and modeling methods has on maglevs' runnability. The study constructed equations of motion on 4-DOF, 6DOF, and 10-DOF vehicles respectively and carried out numerical analysis, applying 4th Runge Kutta method, in order to run six different model maglev as changing the vehicles speed on the same bridge that had 2000 to 1 deflection. The analysis revealed that maglev's runnability improved as speed was lower and the specific model had higher number of bogey and EMS.