• Geomechanics and Engineering
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• v.36 no.1
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• pp.71-81
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• 2024

This study analyzes the pull-out behavior of tunnel-type anchorage under various joint conditions, including joint direction, spacing, and position, using a finite element analysis. The validity of the numerical model was evaluated by comparing the results with a small-scaled model test, and the results of the numerical analysis and the small-scaled model test agree very well. The parametric study evaluated the quantitative effects of each influencing factor, such as joint direction, spacing, and position, on the behavior of tunnel-type anchorage using pull-out resistance-displacement curves. The study found that joint direction had a significant effect on the behavior of tunnel-type anchorage, and the pull-out resistance decreased as the displacement level increased from 0.002L to 0.006L (L: anchorage length). It was confirmed that the reduction in pull-out resistance increased as the number of joints in contact with the anchorage body increased and the spacing between the joints decreased. The pull-out behavior of tunnel-type anchorage was thus shown to be significantly influenced by the position and spacing of the rock joints. In addition, it is found that the number of joints through which the anchorage passes, the wider the area where the plastic point occurs, which leads to a decrease in the resistance of the anchorage.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.10a
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• pp.202-205
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• 2009

Tubular torsion beam of high strength steel is going about in an automotive rear axle due to the advantages of light weight and efficient rear packaging capability. High strength tubular beam can be manufactured by the hydroforming in order to ensure dimensional accuracy, while a conventional stamping has been used for steel tubular beam. Internal pressure, feeding and their combination are the key factors of controlling the process. Based on the numerical simulation and try-outs, the optimized hydroforming process conditions for the high strength tubular beam were suggested.

• Transactions of Materials Processing
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• v.23 no.2
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• pp.110-115
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• 2014

Low cycle fatigue characteristics are very important in the development of automobile suspension parts. Fatigue properties using the strain life approach are usually obtained from low cycle fatigue tests. However, low cycle fatigue testing requires a lot of time and cost. In the current study, an attempt to estimate low cycle fatigue properties of high strength steel sheet from tensile test and tensile simulations is performed. In addition, low cycle fatigue testing was conducted to compare the fatigue properties obtained from tensile testing and simulations. In conclusion, the results effectively predict the low cycle fatigue properties. However, some deviations still exist.

• International Journal of Automotive Technology
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• v.8 no.4
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• pp.455-465
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• 2007

The bushing element shows nonlinear characteristics in both displacements and frequencies, also with hysteretic responses for repeated vibrational excitations. Since the characteristics of the rubber bushing significantly affects the accuracy of the vehicle dynamic simulation result, it should be accurately modeled in the vehicle suspension model. To develop an accurate bushing model for vehicle dynamics analysis, the bushing characteristics under several excitation inputs must be known. In this paper, a 3-axis tester was used to capture the bushing characteristics. The random inputs, sine inputs, and step inputs were imposed on each axis of the bushing. Also, two-axis inputs, the radial-axial and radial-normal inputs, were simultaneously imposed on the tester. Three-axis inputs including the radial-axial-normal direction were supplied to the tester. Bushing characteristics of each case were precisely analyzed. These results could be available for dynamic modeling of bushing.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2001.10a
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• pp.91-96
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• 2001

When it is considered that many vehicle rides on the road and ride quality is an important method to evaluate vehicle performance with handling, running-over-bump manoeuvre may be suitable for testing ride quality. In this paper, a computed model has roughly steering system and lumped mass, connected by joint each rigid body, and suspension that has beam elements and has shock absorber as force element to represent nonlinear characteristics. A computer simulations for passing over a bump were made with two velocities. One side of vehicle passed over bump in due consideration of driver's habit that driver is subject to avoid a bad ride quality. On simulation, vertical acceleration, pitch angle and roll angle were measured at the mass center of chassis each case.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.3
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• pp.138-144
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• 2003

Recently, the weight reduction of vehicle influences its environment problems and performances. It is a trend that a lot of parts have been currently changed to an aluminum alloy from steel materials. In this study, the shape optimization using an orthogonal array is performed to determine the design of the knuckle which is a part of suspension system. With the material of the weight reduction was achieved by satisfying the constraints of a strength requirement. The orthogonal array of $L_{18}$ is introduced to find the optimum design variables that considers the shape of the knuckle. The characteristic function composed of the objective and the construct is defined to the feasibility. Comparing to the weight of the initial design with steel materials that of optimum design with aluminum alloy material is reduced by 60%.

• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.5
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• pp.48-55
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• 2007

A bushing component of a vehicle suspension system is tested to capture the nonlinear behavior of rubber bushing element using the MTS 3-axes rubber test machine. The results of the tests are used to model the artificial neural network bushing model. The performances from the neural network model usually are dependent on the structure of the neural network. In this paper, maximum error, peak error, root mean square error, and error-to-signal ratio are employed to evaluate the performances of the neural network bushing model. A simple simulation is carried out to show the usefulness of the developed procedure.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.1
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• pp.112-120
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• 2003

In this paper, dynamic track tension fur high mobility tracked vehicle is investigated by multibody dynamic simulation techniques. This research focuses on a heavy military tracked vehicle which has sophisticated suspension and rubber bushed rack systems. In order to obtain accurate dynamic track tension of track subsystems, each track link is modeled as a body which has six degrees of freedom. A compliant bushing element is used to connect track links. Various virtual proving ground models are developed to observe dynamic changes of the track tension. Numerical studies of the dynamic track tension are validated against the experimental measurements. The effects of pre-tensions, traction forces, fuming resistances, sprocket torques, ground profiles, and vehicle speeds, for dynamic responses of track tensions are explored, respectively.

• Proceedings of the KSR Conference
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• 2004.06a
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• pp.726-731
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• 2004

Bogie is the connection device between carbody and wheel in railway vehicles. It is the core part that exert a important effect on the passenger safety and running safety. Bogie largely consists of bogie frame, suspension, brake, wheel set. Static and Dynamic load have acted on it complexly. When the bogie is designed, finite element method, static load test, fatigue test, running test should be considered. Some bogie frame of high speed railway freight car have the problem. It's end beam was cracked. The crack of the end beam have a bad effect on brake system. In that case, the cars would be in danger of derailment.

• Proceedings of the KSR Conference
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• 2004.06a
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• pp.903-908
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• 2004

Among welded structure bogies in use for high speed freight car, a part of bogies manufactured in 1999 and 2000 have found problems that crack occurs in its end beam. In case of a freight car the difference of weight between empty and loading conditions are worse than in case of a passenger car. Moreover its brake system is tread brake without second suspension system. Cracks of end beam is supposed to be due to loading by brake system rather than vertical loading by freight. These cracks can make brake system useless and may be a cause of derailment in the worst case. In this study, we have proposed a simple torsion-free brake shoe holder hanger to remove torsion of hanger bracket which was supposed to be one of causes of cracks and performed finite element analyses. Also static load test was applied in torsion free brake shoe holder.