• Advances in aircraft and spacecraft science
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• 제1권4호
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• pp.379-398
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• 2014

This article discusses the microvibration analysis of a cantilever configured reaction wheel assembly. Disturbances induced by the reaction wheel assembly were measured using a previously designed platform. Modelling strategies for the effect of damping are presented. Sine-sweep tests are performed and a method is developed to model harmonic excitations based on the corresponding test results. The often ignored broadband noise is modelled by removing spikes identified in the raw signal including a method of identifying spikes from energy variation and band-stop filter design. The validation of the reaction wheel disturbance model with full excitations (harmonics and broadband noise) is presented and flaws due to missing broadband noise in conventional reaction wheel assembly microvibration analysis are discussed.

• 제어로봇시스템학회논문지
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• 제17권9호
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• pp.882-887
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• 2011

A spiral electrodynamic wheel is proposed as an actuator for the contactless conveyance of a conductive rod. When rotating the wheel around the rod, a radial force, a tangential force, and an axial force are generated on the rod and cause a screw motion of the rod. The rotation of the rod is the inevitable result due to traction torque of the wheel and the unintended motion to be excluded. However, the rotating speed of the rod should be measured without mechanical contact to be cancelled out through the controller, so the electrodynamic wheel is used as a sensor measuring the rotating speed of the rod indirectly as well as an actuator. In this paper, we model the magnetic forces by the proposed wheel theoretically and compare the derived model with simulation result by Maxwell, and analyze influences on the magnetic forces by key parameters constituting the wheel. The feasibility of the conveyance system is verified experimentally.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2012년도 춘계학술대회 논문집
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• pp.31-32
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• 2012

• 소성∙가공
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• 제23권2호
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• pp.116-121
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• 2014

Low pressure die casting and flow forming have been successfully used to produce sound road wheels from magnesium alloy AM80. In the current study, high speed compression testing was initially conducted to simulate the flow forming of a Mg wheel. Subsequently the flow forming was simulated with "Forge$^{TM}$", an FEM software package. On the basis of flow forming simulations, the flow forming of the Mg wheel was performed under different conditions. For the flow forming experiments, the preform castings were made by low pressure die casting from AM80, a commercial magnesium alloy. In flow forming of the magnesium preform wheel, the flow forming of the Mg wheel was successfully accomplished when the feed rate was less than half that for the forming of an aluminum road wheel. The reduction in feed rate was 52%. Finally, a comparison with the flow forming simulations was made.

• 한국기계가공학회지
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• 제13권2호
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• pp.117-123
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• 2014

In order to provide a mobile robot with omnidirectionality, various types of omnidirectional wheels have been developed. This paper deals with an improved design and structural analysis of a Mecanum wheel, which is the type of omnidirectional wheels most commonly used in industrial fields. A geometric formulation for manufacturingthe Mecanum wheel is presented and two types of Mecanum wheels are designed and fabricated in this research. While conventional assembled-type Mecanum wheels have a complicated structure and the high possibility of mutual interference between sub-components, a unified type of Mecanum wheel reduces the number of sub-components and increases the degree of structural rigidity. The stress and strain properties of the two designs are compared to confirm the quantitative improvement of the new design by a commercial structural analysis tool. The analysis results show that the unified type of Mecanum wheel has properties superior to the assembled type of Mecanum wheel in terms of its ability to reduce interference.

• 한국정밀공학회지
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• 제3권2호
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• pp.55-61
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• 1986

The study is concerned with the investigation of grinding factor affecting the AE Source by means of the relation between the amplitude level of AE signal and the depth of wheel engagement in surface grinding by AE method. As the result, work velocity was confirmed that the amplitude of AE signal had almost constant value in comparison with the depth of wheel engagement. But the depth of wheel engagement and the width of wheel engagement were proportional to the amplitude of AE signal. Therefore, when the AE Source was classified by 3-zone, Ws and Wf were affected by the depth of wheel engagement and that Wr was affected by the width of wheel engagement. Also, the adaptability of the AE method was studied about the detection of tool life of grinding wheel, sparkout and initial contact point.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2010년도 추계학술대회
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• pp.323-324
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• 2010

In this paper, outer rotor type of in-wheel switched reluctance motor(SRM) has been design and analyzed for Welfare Neighborhood Electric Vehicle(WNEV). Designed outer rotor type of in-wheel SRM is set to 4-wheel of WNEV. the motor is 6/8 and outer rotor type. and the driving load and motor characteristics are determined and designed.

• 한국정밀공학회지
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• 제29권12호
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• pp.1296-1303
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• 2012

There is a certain limit to reproduce phenomena between the real vehicle and road, since the existing methods to verify durability of the wheel are mostly uni-axial tests. And the change of durability of the wheel can't be predicted since these tests don't consider the camber angle and lateral force as important factors. In this paper, the FE models of the wheel-tire and drum are created. Then, the vertical and lateral loads are applied to wheel-tire assembly and the camber angle is applied by inclining the wheel-tire assembly to the drum. Based on the analysis result, the crack position is predicted to be created in the body of the wheel. The variation of the stress according to the camber angle is verified and the maximum spot of the stress changes continually.

• 대한기계학회논문집A
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• 제21권9호
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• pp.1507-1519
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• 1997

This paper aims to clarify the effects of grinding conditions on bending strength in surface grinding of various ferrites with the resin bond diamond wheel. The main conclusions obtained were as follows. At a constant material removal rate, the strength improves with increased wheel depth of cut and decreased workpiece speed. It is desirable to grind at higher peripheral wheel speed and under the critical workpiece speed presented in this paper. Grinding the ferrite of higher brittleness, the wheel depth of cut limited to hold 50% of their inherent strength becomes lower. The effect of various grinding conditions on bending strength becomes more larger in the order of Sr, Mn-Zn and Cu-Ni-Zn. When using the diamond grain of the lower toughness, the bending strength becomes higher, and the wheel wear occurs faster. Considering both bending strength and wheel wear rate, the best concentration of wheel is 100. The ground surfaces exhibit that the fracture process during grinding becomes more brittle in the order of Sr, Mn-Zn and Cu-Ni-Zn.

• 한국안전학회지
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• 제30권5호
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• pp.92-99
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• 2015

The diameter of a new wheel in EMUs is 860mm and it can be used up to 773mm. To obtain an predefined acceleration despite wheel diameter changes, the tractive efforts of the vehicles must be properly controlled. In the commencement of this study, acceleration tests were performed for empty EMUs when the wheel diameter was changed to 860mm, 820mm and 780mm, respectively. In order to deal with more complicated running conditions, we developed dynamic simulation models of the EMUs using VI-Rail, and simulated the models in empty and full passenger loads, respectively. Using the simulation results, we analyzed the gradient of time-velocity graphs by considering the changes of the total weight vehicles and moment of inertia of the wheelsets as well as tractive effort according to the wheel diameter changes. As the results, it was found that there are significant differences in acceleration performances according to the wheel diameters and the payloads of EMUs. In case of 860mm which is the maximum wheel diameter, the test & simulation results show that the vehicle couldn't reach the predefined acceleration, 3.0km/h/s, due to lack of tractive effort.