• International Journal of Automotive Technology
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• v.7 no.1
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• pp.101-107
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• 2006

The force and moment simulation of a steady-state rolling tire taking the effect of tread pattern into account is described using a steady-state transport method with ABAQUS. Tread meshes can not fully consider a tread pattern because detailed tread meshes are not allowed in the steady-state transport method. Therefore, the tread elements are modeled to have orthotropic property instead of isotropic property. The force and moment simulation has been carried out for the cases of both isotropic and orthotropic properties of tread elements. Both cases of simulation results are then compared with the experimental results. It is verified that the orthotropic case is in a better agreement with the experimental result than the isotropic case. Angle effects of tread pattern have been studied by changing the orientation angle of orthotropic property of tread. It is shown that the groove angle in the tread shoulder region has a more effect on force and moment of a tire than that in the tread center region.

• IE interfaces
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• v.10 no.2
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• pp.109-114
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• 1997

The tread pattern of tire is represented by a great number of design factors, such as groove breadth of circumference direction, breadth direction, rib breadth, block length, kerfs, tread breadth and tread radius, etc. It is not efficient in time and cost to analyze the rolling resistance for a great number of real tread pattern, because It requires lots of pattern forming handwork. In order to optimize tread pattern for rolling resistance, the experiment is planed and analyzed by Taguchi's robust design methods. We identified the important design factors for Rolling Resistance, determined the optimal condition and calculated prediction value which is related. Using the experiment data and the analyzed data, we developed the program which could predict Rolling Resistance. It is expected that time and cost may be reduced in designing and developing new tire tread pattern.

• Proceedings of the KSR Conference
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• 2002.05a
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• pp.423-430
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• 2002

This study was started to develop maintenance technology for wheel tread suitable domestic railway environment. As a pre-study to develop optima] wheel tread, we analyzed the wear characteristics of wheel tread that is being applied to railway rolling-stock in KNR. To analyze wheel wear characteristics. we have conducted the simulation and experiment for passenger rolling-stock and obtained useful datum. Here, we describe some results.

• Proceedings of the KSR Conference
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• 2003.05a
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• pp.641-644
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• 2003

The running safety of the rolling stock depends on the design characteristics and the contact condition between wheel and railway. In this study, it is analyzed how equivalent conicity of wheel tread or its characteristics has influence on the running safety.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.6
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• pp.164-170
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• 2003

The finite element analysis of tires has been conventionally performed by either neglecting tread pattern or modeling only circumferential grooves. Besides, the tire analysis has been mainly limited to static or steady state rolling analysis. In this paper, a transient dynamic analysis of a patterned tire rolling over a cleat with an explicit finite element program is presented. The patterned tire with detailed tread blocks is modeled by a systematic mesh generation procedure, in which tire body and tread pattern meshes are separately generated in the beginning and then both meshes are combined by the tie constraint method. The cleat impact analysis is conducted by using both the patterned tire and the smooth tire models to predict the cleat enveloping characteristics. It is seen that the analysis results of the patterned tire model are in a good agreement with the experimental results.

• Journal of Biosystems Engineering
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• v.21 no.3
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• pp.293-305
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• 1996

Effects on the tractor vibrations of tread, wheelbase and axle load distribution were analyzed by using mathematical models of tractor and random road surface. A 4 degrees of freedom tractor model was developed to predict the bounce, pitch and roll motions of tractor. The front axle which is constrained to roll with respect to tractor body was also included in the model. A random road profile was generated and used as an excitation input to the tractor. Output vibrations of the model were predicted and analyzed by a computer simulation method. In general, longer tread tends to reduce rolling and longer wheelbase does bouncing and pitching motions. Tractor vibrations were minimum when the ratio of front to rear axle loads was in the range of 30:70-35:65. Sensitivity analysis showed that rolling and pitching motions most sensitively varied with changes in tread and wheelbase while bouncing motion did with the location of mass center.

• Transactions of Materials Processing
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• v.15 no.8 s.89
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• pp.562-567
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• 2006

Micro-alloyed steel or heat-treatment-free used in clean technology have been replacing for conventional quenched-and-tempered structural steels since the micro-alloyed forging steel was developed in early 1970s in Germany for saving money of heat treatment, simplified process, short delivery and good productivity. In this paper, ball stud assembled in steering system for automobile was selected to compare conventional process making heat treatment with new process using high strength micro-alloyed steel without heat treatment. The conventional process for ball stud was composed of a total of 6 steps including upsetting, forward extrusion, machining, burnishing and tread rolling with heat treatment and shot blasting. As opposed to conventional process, newly proposed process for ball stud using the clean technology without heat treatment is simplified such as forward extrusion, heading, upsetting, forming having a flange shape and tread rolling. Also net shape forming process to achieve specified process not to include machined step fur manufacturing the ball stud was applied to newly simplified process since micro-alloyed steel is difficult to be formed.

• International Journal of Automotive Technology
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• v.1 no.1
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• pp.26-34
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• 2000

The new numerical procedure for hydroplaning has been developed by considering the following three important factors; fluid/structure interaction, tire rolling, and practical tread pattern. The tire was analyzed by FEM with Lagrangian formulation and the fluid is analyzed by FVM with Eulerian formulation. Since the tire and the fluid are modeled separately and their coupling is automatically computed by the coupling element, the fluid/structure interaction of the complex geometry such as the tire with the tread pattern can be analyzed practically. We verified the predictability of the hydroplaning simulation in the different parameters such as the water flow, the velocity dependence of hydroplaning, and the effect of the tread pattern on hydroplaning. In order to predict the streamline in the contact patch, the procedure of the global-local analysis was developed. Since the streamline could be predicted by this technology, we could develop the new pattern in a short period based on the principle; "make the stream line smooth".

• Journal of Institute of Control, Robotics and Systems
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• v.14 no.10
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• pp.1022-1028
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• 2008

This article presents an omni-tread snake robot that designed to locomote on narrow space and rough terrain. The omni-tread snake robot comprises three segment, which are linked to each other by 2 degrees of freedom joints for the pitch and yaw motion. Moving tracks on all four sides of each segment guarantee propulsion even when the robot rolls over. The 2 DOF joint are actuated by 2 servo motors which produce sufficient torque to lift the one leading or trailing segments up and overcome obstacles. This paper applies articulated steering technique to get omni-tread snake robot's kinematics model.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.966-970
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• 2011

The thermo-mechanical interaction between brake block and wheel tread during braking has been found to cause thermal crack on the wheel tread. Due to thermal expansion of the rim material, the thermal cracks will protrude from the wheel tread and be more exposed to wear during the wheel/block contact than the rest of the tread surface. The wheel rim is in residual compression stress when is new. After service running, the region in the tread has reversed to tension. This condition can lead to the formation and growth of thermal cracks in the rim which can ultimately lead to premature failure of wheel. In the present paper, the thermal cracks of railway wheel, one of severe damages on the wheel tread, were evaluated to understand the safety of railway wheel in running condition. The residual stresses for damaged wheel which are applied to tread brake are investigated. Mainly X-ray diffusion method is used. Under the condition of concurrent loading of continuous rolling contact with rails and cyclic frictional heat from brake blocks, the reduction of residual stress is found to correlate well with the thermal crack initiation.