• Title/Summary/Keyword: starting velocity curve

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Modeling and Simulation of the Linear Density Variation by Repetitive MD-Impacts in a Winding/Unwinding Control Process (Winding/Unwinding 제어공정에서 반복 충격에 기인한 MD-밀도 변동의 모델링과 시뮬레이션)

  • Huh You;Kim Hyung-J.;Kim Jong-S.;Chun Doo-H.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2006.05a
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    • pp.321-322
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    • 2006
  • In many manufacturing processes such as web formation, manufacturing of paper and nonwoven, fabric weaving, etc., planar sheets are transported and at the same time appropriate tension is imposed. The input material rolled up on beams is fed by unwinding the beam and the processed is then taken up on beams by winding it. While processed, the planar sheets are thrown under the processing load of impulse form, which causes irregular thickness of the processed sheet. To improve the quality of the product, a dynamic model is needed and the dynamic characteristics is to be analyzed by simulation. This study shows that density variation dynamics of the in-process-sheet in the machine direction can be described at each moment of disturbing impacts in forms of difference equations, while the impacts and tension, the time-dependency of the material properties were taken into account. Simulation showed the most serious variation of the density occurred in the process starting phase. The starting velocity curve with step form showed the least variation of the density. As the time order of the function of the starting velocity cure becomes higher, the density variation gets greater.

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Antisymmetric S-curve Profile for Fast and Vibrationless Motion (고속 저진동 운동을 위한 비대칭 S-커브 프로파일)

  • Rew Keun-Ho;Kwon Jeong-Tae;Park Kyoung-Woo
    • Journal of Institute of Control, Robotics and Systems
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    • v.12 no.10
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    • pp.1012-1017
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    • 2006
  • By breaking the symmetry of the velocity profile in the S-curve, we developed a fast starting and smooth ending motion profile, named asymmetric S-curve(AS-curve). The problem for generating motion profile is formulated, and the algorithm for the AS-curve is derived and the flow chart of the AS-curve is illustrated. By various simulations, the derived algorithm is tested and shows the validity. This AS-curve can be applied to the high precision machines where fast and vibrationless motion is required in the near future.

An Experimental Study on Performance and Flow Characteristics of Automotive Sirocco Fan (자동차용 시로코팬의 성능 및 유동특성에 관한 실험적 연구)

  • 유성연;이대웅
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.14 no.11
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    • pp.954-963
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    • 2002
  • For the optimal design of an automotive blower system, effects of the scroll cut-off starting angle, the clearance between blade tip and bellmouth, and the scroll expansion angle on the performance of sirocco fan are investigated experimentally. Best performance is achieved at fan exposure ratio $\Deltae/r_c$,/TEX> =1.0, and clearance ratio $\DeltaeC/C=0.62. Flow characteristics inside sirocco fan are also studied by using LDV. Flow patterns in the inside of fan can be classified into three regions. Velocity vector has the same direction as rotational direction of fan at 0~$120^{\circ}$, toward the fan blades at 150~$180^{\circ}$, and opposite direction at 210~$330^{\circ}$. Turbulent intensity is relatively high near the cut-off edge in the scroll housing.

Application of the Taguchi Method to the Analysis of the Numerical Parameters Influencing Springback Characteristics (스프링백 특성에 영향을 미치는 수치변수의 분석을 위한 다구치 실험계획법의 응용)

  • Kim, Hyung-Jong;Jeon, Tae-Bo
    • Journal of Industrial Technology
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    • v.20 no.A
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    • pp.211-218
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    • 2000
  • It is desirable but difficult to predict springback quantitatively and accurately for successful tool and process design in sheet stamping operations. The result of springback analysis by the finite element method (FEM) is sensitively influenced by numerical factors such as blank element size, number of integration points, punch velocity, contact algorithm, etc. In the present work, a parametric study by Taguchi method is performed in order to evaluate the influence of numerical factors on the result of springback analysis quantitatively and to obtain the combination of numerical factors which gives the best approximation to experimental data. Since springback is determined by the residual stress after forming process, it is important to evaluate stress distribution accurately. The oscillation in the time history curve of stress obtained by the dynamic-explicit finite element method says that the stress solution at termination time is in very unstable state. Therefore, a variability study is also carried out in this study in order to assess the stability of implicit springback analysis starting from the stress solution by explicit forming simulation. The U-draw bending process, one of the NUMISHEET '93 benchmark problems, is adopted as an application model because it is most popular one for evaluating the springback characteristic.

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A Parametric Study on the Springback Considering the Stress Variability in Explicit Finite Element Analysis (외연적 유한요소해석에서의 응력 변동성을 고려한 스프링백 영향 인자 연구)

  • Lee K. D.;Kwon J. W.;Jun B. H.;Kim S. J.;Kim H. J.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2000.10a
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    • pp.136-140
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    • 2000
  • It is desirable to predict springback quantitatively and accurately for the tool and process design in sheet stamping operations, however, it is blown very difficult. The result of springback analysis by the finite element method is sensitively influenced by numerical factors such as blank element size, number of integration point, punch velocity, contact algorithm etc. In the present work, a parametric study by Taguchi method is performed in order to evaluate the influence of numerical factors on springback Quantitatively and to obtain the combination of numerical factors which yields the best approximation to experimental data. Since springback is determined by the residual stress after forming process, it is important to evaluate stress distribution accurately. The oscillation in the time history curve of stress obtained by explicit FEM says that the stress solution at termination time is in very unstable state. Therefore, a variability study is also carried out in this study in order to assess the stability of implicit springback analysis starting from the stress solution by explicit forming simulation. The 2D draw bending process, one of the NUMISHEET '93 benchmark problems, is adopted as an application model.

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Fatigue Analysis of Reduction Gears Unit in Rolling Stock Considering Operating Characteristics (운행특성을 고려한 철도차량 감속기의 피로해석)

  • Kim, Chul-Su;Kang, Gil-Hyun
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.12 no.3
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    • pp.1085-1090
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    • 2011
  • To assure the safety of rolling stock, it is important to perform the fatigue analysis of reduction gear unit in rolling stock considering a variation of velocity and traction motor capability. This paper presents fatigue analysis of the damage of reduction gear unit of railway vehicle under variable amplitude loading(VAL) based on quasi-static fatigue analysis using finite element model and linear Miner's rule. The VAL for the simulation was constructed from the tractive effort curve and train run curves of railway vehicle under commercial operation condition using MSC.ADAMS dynamic analysis. The finite element model for evaluating the carburizing effect on the gear surface was used for predicting the fatigue life of the middle gear based on strain-life based approach. The results showed that the frequent high starting torque due to a quick start as well as increasing numbers of stops at station would decrease the fatigue life of reduction gear unit.

A Study on the Goal Setting Method for Increasing the Holed Probability in Slope Putting Stroke on an Artificial Putting Surface

  • Park, Jin;Kim, Ji Hyeon;Jung, Jong Min
    • Korean Journal of Applied Biomechanics
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    • v.27 no.4
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    • pp.269-278
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    • 2017
  • Objective: The purpose of this study was to develop a goal setting method for increasing the probability of a holed in a side inclined putting stroke. Method: Three-dimensional video data was recorded at a frequency of 120 hz per second after synchronizing 19 infrared motion capture systems (Qualisys, Gothenburg, Sweden). Putting green used a polycarbonate plate ($1.2{\times}2.4{\times}0.01meter$) with coefficient of friction (${\mu}=0.062$) and a real curve of the actual hole. Results: The velocity ratio between the club and the ball was 1:1.6 under various ball speed conditions in this study. The overall position of the break is 1 m to 1.4 m from the point where the ball leaves. If there is a slope, the ball follows the target line by the straightening force, and when it reaches 1 m position, the straightening force decreases by 30~50% and reaches to the deviation (break) point which is severely influenced by the slope. From here, the ball is aimed in a direction other than the target, and the size is affected by the slope. Conclusion: If there is a side slope, the ball moves away from the straight line, and the larger the slope, the closer the break point is to the starting point of the ball. Therefore, it is necessary to calculate the degree of departure according to the slope carefully, and it is preferable that the slower the speed is, the more the influence of the slope becomes. It is preferable to use the center of the hole as a reference when calculating the departure.

Study on the Behavior of Curved Track in Honam High-Speed Line considering the Running Performanace for HEMU 430-X (HEMU 430-X 주행특성을 고려한 호남고속철도 곡선궤도구조의 거동연구)

  • Kang, Yun-Suk;Um, Ki-Young;Kim, Seog-Won
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.14 no.8
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    • pp.4068-4076
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    • 2013
  • The wheel-rail interaction forces are influenced by the velocity of vehicle, wheel load, alignment (curve radius, cant etc). For the safety of track structure, it is required to evaluate the influences for track and influential factors. Recently, the HEMU 430-X, which was developed by Next Generation High-Speed Rail Development R&D Project, achieved 421.4km/h in a test run of Daegu.Busan section of the Gyeongbu high speed rail on March in 2013. In the case of additional speed-up test on Test-Bed Section(Gongju.Jeongeup: KP 100~128km Osong starting point), the analysis of track forces is required for outer rail by the increase of dynamic force and centrifugal force of vehicle. In this paper, the vehicle speed variation on HSL line is evaluated by TPS analysis considering the tractive effort of HEMU 430-X, tested running resistance and alignment of Honam HSR. And the track forces are evaluated by centrifugal force and impact factor on curved track.

Morphometrical characteristics of River Meandering (하천 사행의 계량형태학적 특성)

  • 이재우;이원환
    • Water for future
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    • v.14 no.1
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    • pp.39-49
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    • 1981
  • The purpose of this study is to examine the meander charactericstics for the rivers in Korea..In this study, the new characteristics factors of meander are proposed, and the relationships among the factors proposed in this study and the existing factors are derived. An attempt is made to find considerable relation among meander characteristics, but width and meander belt did not show any defined trend and considerable scatter of points was observed. Relationships among the meander length, belt and flowrate, etc., which are factors of meander characteristics, are analyzed the 67 rivers above 30km in length. Channel shape factor which is the ratio of the length from the starting point to the end to the channel lenght, tortuosity which is the ratio of the curved channel length against the channel length are suggested for a new characteristics factor of meander. They are well correlated with channel length, Horton's shape facotr and meander gradient, consequently have to be important measures of river meander. The result of the detailed comparison and the analysis of degree of sinuosity, velocity and water surface slop are brought light on the fact show that the curved reach is morestable than the straight one. The ratio of the meander length to the meander belt and its accumulative frequency showed excellent correlationship when plotted on the semi-log paper. The results of regression analysis of meander belt and meander length show linear for the South Han river branches and power curve for the Geum river and the Nakdong river branches.

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