• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2008년도 춘계학술대회 논문집
• /
• pp.981-982
• /
• 2008

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2005년도 추계학술대회 논문집
• /
• pp.20-23
• /
• 2005

The service demands of railway vehicles have become severe in recent years due to a general increase in operating speeds. It is very important to evaluate the fracture mechanics characteristics with respect to high-speed train wheel. In the present study, fracture mechanics characterization tests were carried out in accordance with various wheel materials. The result shows that fracture mechanics characteristic should be considered in the design code of the wheel materials.

• Tribology and Lubricants
• /
• 제30권6호
• /
• pp.364-369
• /
• 2014

To assess the wear behavior of rails against subway rail car wheels, we investigate the sliding wear behavior of pins derived from two types of rails (normal rails and heat-treated rails) against a disc derived from a subway rail car wheel, using a pin-on-disc-type tribometer. We base the sliding wear test conditions on the sliding conditions for wheel flange-rail gauge corner contact. We demonstrate the remarkable transition in the wear behavior of the pins derived from the rails, from severe wear to mild wear, as a function of the sliding distance. The wear rate of the heat-treated rail material in the running-in wear region is much lower than that of the normal rail material. Furthermore, the wear rates of the pins in the running-in wear region decrease with increasing hardness and with decreasing sliding speed. However, there is little difference between the heat-treated rail pin and the normal rail pin in the wear rate in the steady-state wear region. Stricter controls on the decarburized layer beneath the surface of rails are required to reduce the wear rate in the running-in wear region.

• 한국안전학회지
• /
• 제27권2호
• /
• pp.1-6
• /
• 2012

Uniaxial and biaxial torsional fatigue tests were conducted on the samples extracted from urban railway wheel steel. Ultimate and yield strengths of the steel were 1027.7 MPa and 626 MPa, respectively. The uniaxial fatigue limit was 422.5 MPa, corresponding 67% of the ultimate tensile strength. The ratio of ${\tau}_e/{\sigma}_e$ was 0.63. Fatigue strength coefficient and exponent were 1319.5 MPa and 0.339, respectively. Maximum principal and equivalent strain were found to be adequate parameter to predict fatigue lifetime of the steel under multiaixal fatigue condition.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
• /
• pp.621-629
• /
• 2011

Uniaxial and biaxial torsional fatigue tests were conducted on the samples extracted from urban railway wheel steel. Ultimate and yield strengths of the steel were 1027.7 MPa and 626 MPa, respectively. The uniaxial fatigue limit was 422.5 MPa, corresponding 67% of the ultimate tensile strength. The ratio of ${\tau}_e/{\sigma}_e$ was 0.63. Fatigue strength coefficient and exponent were 1319.5 MPa and 0.339, respectively. Maximum principal and equivalent strain were found to be adequate parameter to predict fatigue lifetime of the steel under multiaixal fatigue condition.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2004년도 추계학술대회 논문집
• /
• pp.601-605
• /
• 2004

Railway wheel is the important element of rolling-stock in the viewpoint of running safety. Thus, the material properties of strength, fatigue crack, durability are needed, and the standards for test and criteria of whee] are established to guarantee quality of wheel. In the meantime, the suppliers for wheel in domestic are varied from domestic monopolization to diverse company of China, Russia, Czech Republic, etc. The uniform quality of wheel is important from a maintenance point of view. We collected wheel samples of diverse vendors to analyze the uniformity of wheel on the basis of korea national standard. We tested material properties and analyzed the test data statistically.

• 한국산림과학회지
• /
• 제108권3호
• /
• pp.322-328
• /
• 2019

본 연구는 임도 유지관리 및 보수를 위한 기초자료를 제공하기 위하여 경상북도 영양군 임도를 대상으로 동평판재하시험(light drop weight test), 들밀도 시험 및 입도분석을 이용하여 개설시기 및 횡단위치별(성토부 차륜부(T0), 노면 중앙부(C), 절토부 차륜부(T1))에 따른 임도노반 지지력 분석을 실시하였다. 들밀도 및 입도분석결과, 들밀도는 2011년 개설임도가 $2.0694g/cm^3$으로 가장 높은 값을 나타냈으며, 2017년 개설임도가 $1.7443g/cm^3$으로 가장 낮은 값을 나타내었다. 입도분석은 2017년 개설임도에서 큰 골재의 비율이 가장 높게 나타났으며, 시기가 늦어질수록 큰 골재의 비율이 줄어드는 경향을 나타냈다. 동평판재하시험결과, 2011년 개설임도 $E_{vd}$가 평균 $35.9MN/m^2$, 2014년은 평균 $31.1MN/m^2$, 2016년은 평균 $26.7MN/m^2$, 2017년은 평균 $23.7MN/m^2$로 2011년 개설임도가 가장 높은 $E_{vd}$를 나타냈다. 또한 성토 차륜부는 평균 $21.2MN/m^2$, 절토 차륜부는 평균 $36.71MN/m^2$ 그리고 중앙부는 평균 $29.8MN/m^2$로 절토 차륜부가 가장 높은 $E_{vd}$를 나타냈다.

• 한국안전학회지
• /
• 제28권4호
• /
• pp.8-13
• /
• 2013

Fatigue crack growth tests were conducted on urban railway wheel steel under mode I and mixed-mode conditions. Fatigue crack growth rates were evaluated in terms of equivalent stress intensity factor ranges, using both the extended and projected crack lengths. The equivalent stress intensity factor range with the growth rate results obtained under mode I loading conditions can be used to predict the crack growth rate under mixed-mode loading conditions. Extended crack length rather than projected crack length is appropriate for the prediction of the crack growth rate under the mixed-mode loading conditions.

• 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.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2010년도 춘계학술대회 논문집
• /
• pp.583-589
• /
• 2010

This paper describes the design process and the test of split wheel-mounted brake discs for high speed train with maximum speed 180km/h. A disc set composed 2 disc rings and individual rings are partitioned into 3 pieces with the same circumferential angle. Because partitioned disc rigs are exposed to severe centrifugal force as the vehicle speed increase, finite element analyses used in the design process to ensure mechanical safety. A prototype was verified its mechanical safety through the spin test up to 250km/h. 2 prototypes for 1 wheelset are mounted to Korean Tilting Train(TTX) and have been running over 15,000km