• 한국자동차공학회논문집
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• 제5권1호
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• pp.101-109
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• 1997

A tool for the dynamic simulation and design technique of the excavator plays an important role in the prediction of dynamic behavior of the excavator in the initial design stage. In this paper, a flexible multibody dynamic analysis model including track of the crawler type excavator is developed using DADS and ANSYS. Through the driving simulation of the excavator travelling over rough road track, frequency characteristics of the upper frame and cabin are obtained, and the reaction forces acting on the track rollers are also presented for the fatigue life estimation. The effect of boom vibration modes on the joint reaction forces and accelerations is presented from the swing simulation.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.699-704
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• 2003

A Internet-based dynamic simulation system, called P-DYN, for multibody dynamic systems is developed. All the interfaces of the system are accessible via Web browsers, such as Netscape or Explorer. The system uses a template type P-DYN/Modeler as a preprocessor. The P-DYN postprocessor composed of P-DYN/Plotter and P-DYN/Animator is developed in JAVA. The P-DYN/Solver for predicting the dynamic behavior is run on the server. Anyone who wants to simulate the dynamics of multibody systems or share results data can access the analysis system over the Internet regardless of their OS, platform, or location.

• International Journal of Precision Engineering and Manufacturing
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• 제4권6호
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• pp.50-60
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• 2003

A web-based dynamic simulation system, called O-DYN, for multibody systems is developed. All the interfaces of the system are accessible via web browsers, such as Netscape or Explorer. The system uses a block-diagram type O-DYN/Modeler developed in JAVA Applet as a preprocessor. The O-DYN postprocessor composed of O-DYN/Plotter and O-DYN/Animator is developed in JAVA Applet. The O-DYN/Solver for predicting the dynamic behavior is run on the web server. Anyone who wants to simulate the dynamics of multibody systems or share results data can access the analysis system over the internet regardless of their OS, platform, or location.

• 소음진동
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• 제8권1호
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• pp.203-211
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• 1998

In order to find out relationship between hit probability and gun firing of a moving tank, a turret and flexible gun system model has been developed using a recursive flexible multibody dynamics. For a firing simulation model, nodal coordinates for a finite element model of a flexible gun have been employed to include transverse loads to the gun tube due to moving bullet and ballistic pressure. Modal coordinates are also used to represent the motion induced gun vibration before a firing occurs. An efficient switching technique from modal equations to nodal equation has been introduced for an entire gun firing simulation with a rotating turret.

• Journal of Mechanical Science and Technology
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• 제19권spc1호
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• pp.395-402
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• 2005

This paper deals with modeling and computer simulation of a full multibody vehicle model for a driving simulator. The multibody vehicle model is based on the recursive formulation and a corresponding simulation code is generated automatically from AUTOCODE, which is a symbolic computation package developed by the authors using MAPLE. The paper describes a procedure for automatically generating a highly efficient simulation code for the full vehicle model, while incorporating realistically modeled components. The following issues have been accounted for in the procedure, including software design for representing a mechanical system in symbolic form as a set of computer data objects, a multibody formulation for systems with various types of connections between bodies, automatic manipulation of symbolic expressions in the multibody formulation, interface design for allowing users to describe unconventional force-and torque-producing components, and a method for accommodating external computer subroutines that may have already been developed. The effectiveness and efficiency of the proposed method have been demonstrated by the simulation code developed and implemented for driving simulation.

• 한국철도학회논문집
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• 제5권3호
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• pp.187-195
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• 2002

It is important to predict the crash behavior of trains to improve their crashworthiness. This paper investigates the simulation of high-speed train crashes in three dimensions using multibody dynamics. At present, little is known about three-dimensional crash simulations. This study shows that it is possible to simulate overriding and lateral buckling, including results from one- or two-dimensional simulations. Several parameters, however, such as computational time and large deformation of structures, need further investigation.

• 동력기계공학회지
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• 제16권4호
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• pp.12-16
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• 2012

In this paper, the equations of motions for planar multibody dynamics are established for considering the parallel programming based on GPU. Cartesian coordinates are used to formulate the equations of motion and implicit integration method called HHT-alpha is employed. Open chain multibody system is considered for computer simulation. CUDA toolkit is employed for establishing the GPU parallel programming. The exactness of the analysis is verified from the comparison with ADAMS. The results from parallel computing based on GPU are compared with the results from the sequential programming based on CPU in terms of calculation time. The multiple pendulum with bodies and joints is employed for the computer simulation. In the pendulum system that has 290 bodies, the parallel program indicates an improved efficiency of about 25.5 second(15.5% improvement). It is noted that the larger the size of system is, the time efficiency is better.

• Journal of Mechanical Science and Technology
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• 제19권spc1호
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• pp.411-421
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• 2005

The development and implementation of an appropriate methodology for the accurate geometric description of track models is proposed in the framework of multibody dynamics and it includes the representation of the track spatial geometry and its irregularities. The wheel and rail surfaces are parameterized to represent any wheel and rail profiles obtained from direct measurements or design requirements. A fully generic methodology to determine, online during the dynamic simulation, the coordinates of the contact points, even when the most general three dimensional motion of the wheelset with respect to the rails is proposed. This methodology is applied to study specific issues in railway dynamics such as the flange contact problem and lead and lag contact configurations. A formulation for the description of the normal contact forces, which result from the wheel-rail interaction, is also presented. The tangential creep forces and moments that develop in the wheel-rail contact area are evaluated using : Kalker linear theory ; Heuristic force method ; Polach formulation. The methodology is implemented in a general multibody code. The discussion is supported through the application of the methodology to the railway vehicle ML95, used by the Lisbon metro company.

• International Journal of Aeronautical and Space Sciences
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• 제14권2호
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• pp.152-161
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• 2013

This paper presents a control effectiveness analysis of the hawkmoth Manduca sexta. A multibody dynamic model of the insect that considers the time-varying inertia of two flapping wings is established, based on measurement data from the real hawkmoth. A six-degree-of-freedom (6-DOF) multibody flight dynamics simulation environment is used to analyze the effectiveness of the control variables defined in a wing kinematics function. The aerodynamics from complex wing flapping motions is estimated by a blade element approach, including translational and rotational force coefficients derived from relevant experimental studies. Control characteristics of flight dynamics with respect to the changes of three angular degrees of freedom (stroke positional, feathering, and deviation angle) of the wing kinematics are investigated. Results show that the symmetric (asymmetric) wing kinematics change of each wing only affects the longitudinal (lateral) flight forces and moments, which implies that the longitudinal and lateral flight controls are decoupled. However, there are coupling effects within each plane of motion. In the longitudinal plane, pitch and forward/backward motion controls are coupled; in the lateral plane, roll and side-translation motion controls are coupled.

• International Journal of Precision Engineering and Manufacturing
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• 제5권4호
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• pp.50-60
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• 2004

A very flexible beam can be used to model various types of continuous mechanical parts such as cables and wires. In this paper, the dynamic properties of a very flexible beam, included in a multibody system, are analyzed using absolute nodal coordinates formulation, which is based on finite element procedures, and the general continuum mechanics theory to represent the elastic forces. In order to consider the dynamic interaction between a continuous large deformable beam and a rigid multibody system, a combined system equations of motion is derived by adopting absolute nodal coordinates and rigid body coordinates. Using the derived system equation, a computation method for the dynamic stress during flexible multibody simulation is presented based on Euler-Bernoulli beam theory, and its reliability is verified by a commercial program NASTRAN. This method is significant in that the structural and multibody dynamics models can be unified into one numerical system. In addition, to analyze a multibody system including a very flexible beam, formulations for the sliding joint between a very deformable beam and a rigid body are derived using a non-generalized coordinate, which has no inertia or forces associated with it. In particular, a very flexible catenary cable on which a multibody system moves along its length is presented as a numerical example.