• Journal of the Korean Society for Precision Engineering
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• v.17 no.11
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• pp.176-184
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• 2000

Recently, it becomes a very important issue to consider the mechanical systems such as high-speed vehicle and railway train moving on a flexible beam structure. Using general approach proposed in the first part of this paper, it tis possible to predict planar motion of constrained mechanical system and elastic structure with various kinds of foundation supporting condition. Combined differential-algebraic equations of motion derived from both multibody dynamics theory and Finite Element Method can be analyzed numerically using generalized coordinate partitioning algorithm. To verify the validity of this approach, results from simply supported elastic beam subjected to a moving load are compared with exact solution from a reference. Finally, parameter study is conducted for a moving vehicle model on a simply supported 3-span bridge.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.11
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• pp.165-175
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• 2000

In recent years, it becomes a very important issue to consider the mechanical systems such as high-speed vehicles and railway trains moving on elastic beam structures. In this paper, a general approach, which can predict the dynamic behavior of constrained mechanical system and elastic beam structure, is proposed. Also, various supporting conditions of a foundation support are considered for the elastic beam structures. The elastic structure is assumed to be a nonuniform and linear Bernoulli-Euler beam with proportional damping effect. Combined Differential-Algebraic Equations of motion are derived using multibody dynamics theory and Finite Element Method. The proposed equations of motion can be solved numerically using generalizd coordinate partitioning method and Predictor-Corrector algorithm, which is an implicit multi-step integration method.

• Journal of Aerospace System Engineering
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• v.14 no.6
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• pp.18-25
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• 2020

This study investigated the structural behaviors and safety of an electro-mechanical linear actuator and a load simulator with a plate spring. The material and dimensions of the plate spring were determined by theoretically calculating the stress and torsional angle for the rating load of the actuator. Thereafter, a flexible multibody dynamics (FMBD) analysis was conducted on the linear actuator and load simulator to confirm the performance of the load simulator and acquire the reaction forces acting on the actuator and simulator. The structural safety of the linear actuator and load simulator was evaluated via finite element analysis using the aforementioned reaction forces. Consequently, the proposed linear actuator and load simulator were determined to be structurally safe; however, the safety factors for the actuation rod and the housing on the actuator were excessively high. Therefore, the weight and cost must be reduced to improve their design parameters in the future.

• Transactions of the KSME C: Technology and Education
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• v.1 no.1
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• pp.1-6
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• 2013

A SIM card socket is used for a cell phone to fix an USIM card and a push-push mechanism is typically employed in the SIM card socket for a user convenience. A SIM card is inserted with locking when a user pushes the card once and a SIM card is removed with unlocking when a user pushes the card again. A push-push mechanism is operated by a heart-cam structure and a main spring. A cam slider and a cam stick consisting a push-push mechanism may be broken because of the main spring. So, dynamic stress at a cam slider and a cam stick which is generated by a main spring during operating should be analyzed and considered in the push-push mechanism design. In this paper, a flexible multibody model of a push-push mechanism was developed to analyze dynamic stress at a cam slider and a cam stick.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.26 no.4
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• pp.233-239
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• 2013

Recently, a number of wind turbines are being installed due to the increase of interest in renewable, environment-friendly energy. Especially, an offshore wind turbine is being watched with keen interest in that it has no difficulty in securing a site and can get high quality of wind, as compared with a wind turbine on land. The offshore wind turbine is transferred to and installed on the site by an offshore floating crane after it was made in a factory on land such as shipyard. At this time, it is important to secure the safety of the turbine because of its huge size and expensive cost. Thus, a dynamic analysis of the offshore wind turbine which is connedted with the offshore floating crane was performed based on the multibody systems dynamics in this study. As a result. it is shown that the analysis can be applied to verify the safety of a method for the transportation and installation of the offshore wind turbine suspended by the crane.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.26 no.4
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• pp.247-254
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• 2013

In this paper, dynamic response analysis of a heave compensation system is performed for offshore drilling operations based on multibody dynamics. With this simulation, the efficiency of the heave compensation system can be virtually confirmed before it is applied to drilling operations. The heave compensation system installed on a semi-submersible platform consists of a passive and an active heave compensator. The passive and active heave compensator are composed of several bodies that are connected to each other with various types of joints. Therefore, to carry out the dynamic response analysis, the dynamics kernel was developed based on mutibody dynamics. To construct the equations of motion of the multibody system and to determine the unknown accelerations and constraint forces, the recursive Newton-Euler formulation was adapted. Functions of the developed dynamics kernel were verified by comparing them with other commercial dynamics kernels. The hydrostatic force with nonlinear effects, the linearized hydrodynamic force, and the pneumatic and hydraulic control forces were considered as the external forces that act on the platform of the semi-submersible rig and the heave compensation system. The dynamic simulation of the heave compensation system of the semi-submersible rig, which is available for drilling operations with a 3,600m water depth, was carried out. From the results of the simulation, the efficiency of the heave compensation system were evaluated before they were applied to the offshore drilling operations. Moreover, the calculated constraint forces could serve as reference data for the design of the mechanical system.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2004.04a
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• pp.9-16
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• 2004

This paper deals with the development of computational schemes for the dynamic analysis of flexible and nonlinear multibody systems. Different from the existing method, this paper introduces the quaternion algebra to develop the equation of the conservation of energy. Simultaneously, Rodrigues parameters are used to express the finite rotation for the proposed scheme. The proposed energy scheme is derived such that it provides unconditionally stable conditions for the nonlinear problems. Several examples of dynamic systems are presented which illustrate the efficiency and accuracy of the developed energy schemes.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.8
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• pp.1974-1984
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• 1994

This paper presents a relative coordinate formulation for constrained mechanical systems. Relative coordinates are defined along degrees of freedom of a joint. Graph theoretic analyses are performed to identify topological paths in mechanical systems. Cut constraints are generated to handle closed loop systems. Equations of motion are derived in the Cartesian space and transformed to the joint space. Relative generalized coordinates are corrected to satisfy the cut constraints by a parametrizatiom method.

• Transactions of the Korean Society of Mechanical Engineers
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• v.10 no.4
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• pp.450-455
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• 1986

본 연구에서는 직교좌표계 및 Euler-Lagrange 방법을 이용하여 유도된 기본 방정식을 사용하여 앞창닦기기구(windshield wiper mechanism)의 동력학적 해석을 하 였다.모우터가 일정한 각속도로 회전하고 있는 경우와, 토오크가 각속도의 크기에 따라 변화하는 경우 각각에 대해서 강체로 해석할 때와 탄성체로 가정할 때의 해석결 과를 비교하였다.

• Journal of the Korean Society for Railway
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• v.2 no.3
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• pp.1-8
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• 1999

In this paper, descibed was the derived algorithm for calculating contact point between wheel and rail and the developed method for rail modeling. The proposed methods use travelling distance to represent rail center line position vector and rail orientation with respect to Newtonian reference frame. The methods call be easily used ill multibody dynamic analysis. Two numerical examples are shown to verify the validity of the proposed methods.