• 한국정밀공학회지
• /
• 제28권5호
• /
• pp.572-577
• /
• 2011

Curve squealing of inter-city railway vehicle is a noise with high acoustic pressure and rather narrow frequency spectra. This noise turns out to be very annoying for the people living in the neighborhood of locations and the passenger in railway vehicle where this phenomenon occurs. Squealing is caused by a self-exited stick-slip oscillation in the wheel-rail contact. Curve squeal noise of railway vehicles that passed by a factor of the speed limit, so to overcome in order to improve running performance is one of the largest technology. In the present paper, characteristic of squeal noise behavior at the Hanvit-200 tilting train test-site. Curve squealing of railway wheels/rail contact occurs in R400~ R800 curves with a frequency range of about 4~11 kHz. If the curve is less than the radius of wheel frail contact due to |left-right| noise level difference (dBA) shows a significant effect of squeal noise were more likely.

• 한국정밀공학회지
• /
• 제29권6호
• /
• pp.600-606
• /
• 2012

Upon investigation of the damaged wheels for high speed train it was determined that the damage was caused by rolling contact fatigue during operation of train. The major problems that railway vehicle system using wheel-rail has to face during operation of railway vehicle are rolling contact fatigue, cracks in wheels, cracks in rails and wheel-rail profile wear. If these deficiencies are not controlled at early stages the huge economical problems due to unexpected maintenance cost in railway vehicle can be happened. Also, If the accurate knowledge of contact conditions between wheel and rail can be evaluated, the damage of wheel can be prevented and the maintenance operation can save money. This paper presents the applicability of electro-magnetic technique to the detection and sizing of defects in wheel. Under the condition of continuous rolling contact fatigue the damage of wheel has continuously monitored using the applied sensor. It was shown that the usefulness of the applied sensor was verified by twin disc test and the measured damaged sizes showed good agreement with the damaged sizes estimated by electro-magnetic technique.

• 한국철도학회논문집
• /
• 제12권3호
• /
• pp.396-404
• /
• 2009

고속열차의 개발과 함께 구름접촉피로에 의한 레일의 피로균열 및 피로파괴에 대한 연구를 통해 주행안정성을 확보할 수 있는 방안 마련이 필요하다. 따라서 본 연구에서는 Eisenmann의 근사계산식(실용식)을 이용하여 속도, 차륜반경, 궤도지지강성, 침목간격, 축중, 궤도품질에 따른 레일내부 발생응력을 검토하였다. 또한, 유한요소해석을 통해 초기균열의 길이 및 각도, 온도에 따라 레일두부에서 발생하는 전단응력을 검토하여 모드별 응력확대계수를 도출하였다. 이로써 고속철도 레일의 피로수명에 영향을 미치는 주요인자들을 확인하였다.

• Structural Engineering and Mechanics
• /
• 제69권5호
• /
• pp.499-509
• /
• 2019

While the wheel flat is an asymmetrical phenomenon in the railway, majority of researches have used two-dimensional models in the investigation of the effect of wheel flat on the wheel rail forces. This is due to the considerably low computational costs of two dimensional (2D) models although their reliability is questionable. This leaves us with the question of "what is the optimum modeling technique?". It is addressed in this research. For this purpose, two and three dimensional numerical models of railway vehicle/track interaction were developed. The three dimensional (3D) model was validated by comparisons of its results with those obtained from a comprehensive field tests carried out in this research and then, the results obtained from the 2D and 3D models were compared. The results obtained indicate that there are considerable differences between wheel/rail forces obtained from the 2D and 3D models in the conditions of medium to large wheel-flats. On the other hand, it was shown that the results of the 2D models are reliable for particular ranges of vehicle speed, railway track stiffness and wheel-fats lengths and depths. The results were used to draw a diagram, which presents the optimum modeling technique, compromising between the costs and accuracy of the obtained results.

• 한국철도학회논문집
• /
• 제18권4호
• /
• pp.289-300
• /
• 2015

철도 전동 소음은 철도에서 발생하는 대표적인 소음으로서 차륜과 레일의 음향 조도에 의해 가진 된 차륜 및 레일의 진동으로부터 발생한다. 철도 전동 소음 해석 시 레일 방사 소음은 자유 공간에 놓인 레일의 음향 방사 파워를 이용해 원거리에서 계산하므로, 일반적으로 소음원 모델에 지면 반사를 고려하지 않는다. 그러나 레일 주위의 근접 음장을 해석하고 저감 대책을 적용하기 위해서는 지면에 의한 음파의 반사를 고려해야 한다. 본 논문에서는 파수유한요소/경계요소법을 이용해 지면에 의해 발생하는 레일 소음의 변화와 그 특성을 살펴보았다. 해석은 먼저 레일이 강체 지면에 부착된 경우와 레일 패드 높이만큼 강체 지면에서 이격된 경우에 대해 방사효율을 구하고 그 결과를 비교하였다. 이를 통해 레일과 강체 지면의 이격 여부에 따라 레일 방사 소음에 크게 변화함을 확인하였다. 둘째로는 지면에 임피던스 경계조건을 부여하고 레일에서 방사되는 음향 파워 및 지향 특성의 변화를 살펴보았다.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2002년도 춘계학술대회 논문집
• /
• pp.411-416
• /
• 2002

The strength evaluation of a wheel is becoming very important due to the high speed of railway system and the reduction of wheel weight. Therefore, in this study, the influence of thermal stress at tread breaking in Korean High Speed Train wheel was investigated using FEM. During FEM analysis, the mechanical load or wheel-rail contract load and braking load were considered. When 300% of the block force was applied, the maximum von Mises stress of 61.0 ㎫ was found at the outside plate around 400mm far away from the wheel center.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2002년도 춘계학술대회 논문집
• /
• pp.220-227
• /
• 2002

Now, Korea National Railroad is planning many ways to increase the maximum operating speed of train up to 200km/h by 2010. Among those ways, connecting conventional line with the KTX is the strongest alternative. Mostly, conventional lines are consisting of both KS50N and KS6O rail. However, the excessive abrasion might be occurred between wheel and rail when the KTX designed to operate on UIC60 is operating on the conventional line. On this study, new standard of 60kg-class rail considered suitability for both KTX and wheel used in conventional line is presented. It seems to be an effective solution for increasing maintenance costs expected when commercial speed of conventional line is increasing.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2007년도 추계학술대회 논문집
• /
• pp.927-939
• /
• 2007

This paper concerns dynamics of a wheel-axle set on a tangent track which was already published in a book titled "Dynamics of Railway Vehicle Systems" authored by Garg and Dukkipati [1], pointing out several missing terms and erroneous parts in the derived expressions on the conventional governing equations of motion. It is indicated that the x-direction components of normal forces at left and right wheel-rail contact points in the equilibrium axis were missed. Another point is that in deriving the creepages the disturbed velocity components in both x and y directions in the equilibrium axis should not be disregarded in the first term of the numerators. When considering the creepage in the y direction in the body coordinate system, the second term of lateral velocity at the contact point also cannot be neglected. Besides, the hyper-assumptions in the final expressions of vertical components of normal forces at left and right wheel-rail contact points have been recovered in reaching the final stage of analytical model development. Finally it is noteworthy that the process of applying creep theory is deemed to contain a little bit inconsistencies and ambiguities to be clear.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2006년도 춘계학술대회 논문집
• /
• pp.41-42
• /
• 2006

The important factor to evaluate the running safety of a railway vehicle would be the interaction force between wheel and rail(derailment coefficient), for which is one of important factors to check the running safety of a railway vehicle that may cause a tragic accident. In this paper, analysis of coupling term between vertical load and lateral load for install load cell to wheel-set. This result is going to be utilized in formality that verify running safety of tilting vehicles.

• 한국철도학회논문집
• /
• 제6권4호
• /
• pp.239-245
• /
• 2003

In this paper, the track impact factor of conventional line was evaluated using the data for wheel load measured in field and the properties of current operating trains. The equation for track impact factor was presented through the statistical analysis of variational ratio in wheel load and compared with other design equations in domestic and foreign countries. A review on the safety of track system in conventional line was made from the relationship between the velocity and the corresponding impact factor. It was found that the impact factor from the proposed equation is a little less than the values from the equations adopted in both AREA and domestic railway, while it is same as the equation for continuous welded rail(CWR) in Japan. Therefore it could be said that the track satisfies a criteria for dynamic load caused by the train and the corresponding level of safety is guaranteed for dynamic load of the train