• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2007년도 춘계학술대회A
• /
• pp.718-723
• /
• 2007

A three dimensional multibody modeling of a launcher system was developed and dynamic characteristics of the system was carried out. All the components were modeled as rigid bodies, All the components of system, ie; chassis, turret, cage and suspension parts, are modeled as rigid. The force interaction between the ground and tire was modeled as a point contact model. The factors were selected as cause and effect diagram of the MINITAB. To see effect of the stiffness, damping, mass at the launcher system, several cases of suspension parameters were compared and optimal values were selected. The stiffness and the damping coefficient were selected as design variables to minimize the required time for the next fire. The dynamic simulation was carried out using the ADAMS, and the MINITAB was employed for data analysis.

• 한국자동차공학회논문집
• /
• 제20권2호
• /
• pp.47-55
• /
• 2012

This work deals with dynamic analysis of a monorail system with magnetic caterpillar where magnets are embedded inside each articulated element of the caterpillar, augmenting traction force of main rubber wheels to climb up slope up to 15 degree grade. Considerations are first given to determine stiffness of the primary and secondary suspension springs in order for the natural frequencies of car body and bogie associated with vertical, pitch, roll and yaw motion to be within generally accepted range of 1-2 Hz. Equations for calculating magnetic force needed to climb up given slope are derived, and a magnetic caterpillar system for 1/6 scale monorail is designed based on the derivation. To assess the hill climbing ability and cornering stability, and make sure smooth operation of the side and vertical guiding wheels which is critical for safety, a multibody model that takes into account of every component level design characteristics of car, bogie, and caterpillar is set up. Through hill climbing simulation and comparison with measurement of the limit slope, the validity of the analysis and design of the magnetic caterpillar system are demonstrated. Also by studying the curving behavior, maximum curving speed without rollover, functioning of lateral motion constraint system, the effects of geometry of guiding rails are studied.

• 대한기계학회논문집 C: 기술과 교육
• /
• 제3권2호
• /
• pp.97-106
• /
• 2015

Flexible structures are often important components of mechanical assemblies in motion. A flexible structure sometimes must go through assembly steps that cause it to be in a pre-stressed condition when in the starting position for operation. A virtual prototype of the assembly must also bring the model of the flexible structure into the same pre-stressed condition in order to obtain accurate simulation results. This case study is presented regarding the simulation of a constant velocity joint, with a focus on the flexible boot. The case study demonstrates that careful definition of the initial conditions of the boot and flexible body contacts yields high-fidelity simulation results.

• 대한기계학회논문집
• /
• 제12권3호
• /
• pp.450-456
• /
• 1988

본 연구에서는 자동차의 동력학적 해석을 위한 특별프로그램을 만들어서 범용 프로그램인 DADS와 효율성을 비교해 보고자 한다.

• Journal of Mechanical Science and Technology
• /
• 제18권5호
• /
• pp.742-752
• /
• 2004

Many papers have studied computer simulations of elastic bodies undergoing large deflections and large deformations. But there have not been many attempts to check the validity of the numerical formulations because the simulation results could not be matched without correct input data such as material properties and damping effects. In this paper, these values are obtained from real experiment with a high-speed camera and a data acquisition system. The simulation results with the absolute nodal coordinate formulation (ANCF) are compared with the results of real experiments. Two examples, a thin cantilevers beam and a thin plate, are studied to verify whether the simulation results are well matched to experimental results.

• 대한기계학회논문집A
• /
• 제40권6호
• /
• pp.547-555
• /
• 2016

철도차량의 휠의 마모는 주로 곡선 주행 시 발생한다. 휠의 형상 변화는 차량 동적 안정성에 중요한 영향을 미친다. 본 연구에서는 곡선 주행 시 휠 마모 특성 분석을 위해 곡선 반경 크기와 속도를 변경시키면서 휠 마모량을 계산하였다. 다물체 동역학 해석에 기초한 차량 동역학 해석결과로부터 마모인자를 계산하고 BRR(British Rail Research)에서 제시한 마모 모델을 이용하여 휠의 마모량을 계산하였다. 반경 300m에서의 마모량이 다른 반경과 비교하여 매우 큰 것으로 나타났다. 곡선 선로에 윤활유를 도유하는 경우 마모 특성 변화를 분석하기 위해 휠의 답면과 플랜지 부위의 마찰계수를 다르게 하여 휠 마모량을 계산하였다. 도유 시 휠 마모의 개선 효과를 여러 반경에서 계산하고 실제 도시철도구간에서 마모 개선 효과를 확인하였다.

• 대한기계학회논문집A
• /
• 제40권6호
• /
• pp.557-563
• /
• 2016

파력발전시스템의 에너지 흡수 효율은 입사파의 파력과 발전기 구동 동력의 비로 정의된다. 흡수 효율은 파력발전시스템의 동적 거동에 의존하기 때문에 파력발전시스템의 에너지 흡수 효율을 예측하기 위해서 파력발전시스템의 동적 해석이 요구된다. 본 논문에서는 에너지 흡수 효율을 예측하기 위하여 파력발전시스템의 동적 해석을 수행하였다. 파력발전시스템의 동적 해석을 위해서 상용 다물체동역학 해석 프로그램인 RecurDyn을 사용하였고, 부유체에 작용하는 파력을 모델링하기 위해서 Morison equation을 적용하였다. 효율분석 결과 파고가 낮고, 주기가 짧을수록 흡수효율이 높아지는 경향을 보인다.

• Structural Engineering and Mechanics
• /
• 제63권5호
• /
• pp.691-702
• /
• 2017

Clearances are essential for the assemblage of mechanisms to allow the relative motion between the joined bodies. This clearance exists due to machining tolerances, wear, material deformations, and imperfections, and it can worsen the mechanism performance when the precision and smoothly-working are intended. Energy is a subject which is less paid attention in the area of clearance. The effect of the clearance on the energy of a flexible slider-crank mechanism is investigated in this paper. A clearance exists in the joint between the slider and the coupler. The contact force model is based on the Lankarani and Nikravesh model and the friction force is calculated using the modified Coulomb's friction law. The hysteresis damping which has been included in the contact force model dissipates energy in clearance joints. The other source for the energy loss is the friction between the journal and the bearing. Initial configuration and crank angular velocity are changed to see their effects on the energy of the system. Energy diagrams are plotted for different coefficients of friction to see its influence. Finally, considering the coupler as a flexible body, the effect of flexibility on the energy of the system is investigated.

• 한국소음진동공학회논문집
• /
• 제20권8호
• /
• pp.761-766
• /
• 2010

The goal of this study is to analysis natural frequency for different static postures of human leg. To perform this research human leg is modeled by multi-body modeling for the musculoskeletal system. This leg model has biarticular muscles which acting on two joints and the muscles represents some of the major muscles, such as hamstring, of the upper and lower limbs. To obtain each static equilibrium position energy method is employed and to analysis natural frequency linearization method for constrained mechanical system is employed. Static equilibrium position depends on some parameter or condition such as hamstring stiffness or external force. Making a change these parameter the aim of this research can be performed.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2004년도 추계학술대회 논문집
• /
• pp.1113-1118
• /
• 2004

This paper presents the dynamic analysis method for an electromechanical system. The engineer has at his disposal a variety of software simulation tools. However, difficulties arise when the study of the behavior of complex electromechanical systems in combination with coupling element is required. Typical examples of such systems are machines for factory automation, home automation, and office automation. Dynamic systems analysis packages or electronic systems analysis packages offer the restrictive to simulate these mixed systems such electromechanical product. Electronic circuit analysis algorithm is easily incorporated into a multi-body dynamics analysis algorithm. The governing equation of electronic circuit is formulated as a differential algebraic equation form including both electrical and mechanical variables and is simultaneously solved in every time step. This analysis method clearly demonstrates the application potential for mixed electromechanical simulation.