• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.875-879
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• 2007

The effects of the statistical properties of the Coulomb friction coefficients on the dynamic responses of a galloping quadruped robot are investigated in this paper. In general, the Coulomb friction coefficients are assumed to be deterministic for a controller design to achieve required motion characteristics. However, the friction coefficients between the ground and the robot legs are not constant in reality. Therefore, statistical characteristics of the friction coefficients need to be considered for a multi-body modeling of the robot galloping on the ground. The effects of the statistical properties on the dynamic responses of the quadruped robots are investigated.

• Transactions of the Korean Society of Automotive Engineers
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• v.17 no.4
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• pp.63-71
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• 2009

The elastic effects of the valve train components are analyzed by using the finite element models of the rocker arm and valve. The whole equations of motion of the valvetrain of an internal combustion engine formulated by finite element techniques are solved by imposing the contact conditions with the augmented Lagrange multiplier method. The velocity and acceleration constraints as well as the displacement constraints are imposed on the contact points. The numerical simulations show that, even if the magnitude of the elastic deformation of the components is very small, it may have large effects on the valvetrain dynamics of a high-speed engine.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.874-880
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• 2003

Many mechanical systems are over-constrained if only rigid bodies are used to model the system. One example of such system is a satellite system with solar panels. To avoid this over-constrained problem, solar panels can be modeled as flexible bodies. The CMS(Component Mode Synthesis) method is widely used to analyze the flexible multi-body system because it can considerably approximate the deformation of the flexible bodies using small number of well-selected mode. However, it is very difficult to decide the boundary condition and the selection of modes. In this paper, the methods for mode synthesis and setting the boundary condition are presented to analyze the flexible multi-body system with over-constraints. Finally, the reliability of proposed method is verified by solar panel's deployment test.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.5
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• pp.1150-1157
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• 1994

This paper presents dynamic analysis of a hydraulic excavator based on experimental data. A three dimensional multibody model of a hydraulic excavator is modeled for the computer simulation. The hydraulic pressures acting on the cylinders are measured from experiments, and the forces exerting on the cylinders are calculated from the measured pressures. Using these forces, the dynamic analysis of the excavator is carried out to regenerate the motion in the computer simulation. A proper operation scheme is assumed to match the computational result and the experiment. The DADS program is used for the dynamic analysis.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.8
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• pp.1015-1019
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• 2013

To improve the energy efficiency and ride quality of an electric vehicle, it is highly desirable to develop a lightweight suspension system with high travel ratio. Air suspension systems with a rubber tube are often considered optimal for such requirements. In this study, a new lightweight air suspension system with high travel ratio was developed for use in electric vehicles. Furthermore, an FE-based multi-flexible-body dynamics (MFBD) model of the suspension system was developed as a tool for improving the design of an actual suspension system. The MFBD model includes the FE modeling of the rubber tube module as well as other essential parts of the air suspension system. The system parameters for the model were obtained from various experiments. The validity of the developed MFBD model was shown through a comparison between the experimental results and the simulation results.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.2
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• pp.145-152
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• 2018

This study deals with the method of determining the tip-over stability of a truck mounted on a high place operation car that is frequently used to carry out high-altitude work. Multibody Dynamics Program and Zero Moment Point (ZMP) theory are used to include dynamic effects during the car's high place operation. Through a combination of the Multibody Dynamics Program and ZMP, understanding the dynamic effects of the car's operating parts and building a detailed tip-over model of the car permitted a more precise prediction of the car's tipping-over behavior. It is also expected to help reduce the car's development time due to the time-effective simulation and provide safer work levels for the operating guide (in terms of working radius and lifting capability) with the dynamics effects.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.4
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• pp.389-395
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• 2016

Wheel loaders are utilized not only on construction sites, but also for general purposes, such as manufacturing and transportation. Therefore, during the basic design stage of this type of working device equipment, the designer should consider specifications as well as working performance. In this research, a characteristic analysis program was developed for use in the basic design stage of construction equipment using multibody dynamics analysis. In addition, through the optimization of its links, improvements to the lifting capability of a Z-bar-linkage-type wheel loader were suggested. Using the developed program and process, it is possible to reduce the time required for the basic design of the working device.

• Journal of Advanced Marine Engineering and Technology
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• v.41 no.3
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• pp.258-268
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• 2017

In this study, we aim to converge a technology for analyzing the hydraulic circuit of a loading arm with an- other one for analyzing multi-body dynamics by utilizing analysis software SimulationX. Further, this study intends to overcome the limitations of the existing technology for analyzing a hydraulic circuit with a variation at the rotation center of the moving mass and the difficulty of incorporating the behavior in a gravity field. First, the specifications of the hydraulic circuit components were reflected in an analysis model to secure reliability. Hydraulic circuit modeling was then performed using a single analysis model with a verified reliability. Subsequently, the multi-body system (MBS) model of the loading arm was formed. Finally, the analysis model of the hydraulic circuit and the MBS model were converged to check if the circuit analysis result was exactly reflected in the MBS model. The convergence analysis model has development cost-saving effect because it is capable of predicting the dynamic behavior of an object without the prototype.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.1
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• pp.25-30
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• 2014

The dynamic characteristics of a gas circuit breaker depend on the underlying high-speed operating mechanism with a spring-actuated latch system. Many studies have been carried out to reduce the breaking time of circuit breakers. In this study, the optimum latch contour design is determined for reducing the breaking time of a circuit breaker. A multi-body dynamic model of the latch is established for analyzing the dynamic behaviors of the circuit breaker by using the MSC/ADAMS program. Simulation results are matched against experimental data. VisualDoc is employed for determining the optimal latch contour. From the optimum design, the breaking time of a gas circuit breaker is improved by about 8.6%.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.9
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• pp.4142-4148
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• 2013

Because of effective fruit growing and management in the slope land, the use of orchard vehicle with lifting utilities has been increased. For this reason the study on the stability of that vehicle for worker's safety is needed. This study is investigated on the stability estimation of orchard vehicle with four wheels and dual rectangular-type lifting utilities which can be moved on the dirt sloping load. Through the multi-body dynamics analysis on the vehicle mechanism, overturning angles of 19.2 and $34.6^{\circ}$ in the right-left and front-rear direction can be calculated. It is determined tractive resistances and required powers of the wheels. And through the finite element analysis on the frame of lifting utility its maximum von-Mises stress is 146 MPa and it is structural stable. Therefore it is known that the orchard vehicle with wheels and lifting utilities has static and dynamic stability.