Crack Inspection of Railroad Wheel Treads by EMATs

Catastrophic bearing failure is a major concern for the railroad industry because it can lead to costly train stoppages and even derailments. Excessive heat buildup within the bearing is one of the main factors that can warn of impending failure. A question is often raised regarding the transfer of heat from a wheel during braking and whether this can lead to false setouts. Therefore, this work was motivated by the need to understand and quantify the heat transfer paths to the tapered roller bearing within the railroad wheel assembly when wheel heating occurs. A series of experiments and finite element (FE) analyses were conducted in order to identify the different heat transfer mechanisms, with emphasis on radiation. The experimental setup consisted of a train axle with two wheels and bearings pressed onto their respective journals. One of the wheels was heated using an electric tape placed around the outside of the rim. A total of 32 thermocouples scattered throughout the heated wheel, the axle, and the bearing circumference measured the temperature distribution within the assembly. In order to quantify the heat radiated to the bearing, a second set of experiments was developed; these included, in addition to the axle and the wheel pair, a parabolic reflector that blocked body-to-body radiation to the bearing. The appropriate boundary conditions including ambient temperature, emissivity, and convection coefficient estimates were measured or calculated from the aforementioned experiments. The FE thermal analysis of the wheel assembly was performed using the ALGOR™ software. Experimental temperature data along the radius of the heated wheel, the bearing circumference, and at selected locations on the axle were compared to the results of the FE model to verify its accuracy. The results indicate that the effect of thermal radiation from a hot wheel on the cup temperature of the adjacent bearing is minimal when the wheel tread temperature is at 135°C (275°F), and does not exceed 17°C (31°F) when the wheel tread is at 315°C (600°F).

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Fundamental Evaluation of Thermal Crack Resistance for Wheel Fracture Prevention

Design Engineering ◽

10.1115/imece2002-39604 ◽

2002 ◽

Author(s):

Haruo Sakamoto

Keyword(s):

Crack Resistance ◽

Low Cycle Fatigue ◽

Fatigue Behavior ◽

Railroad Wheel ◽

Special Device ◽

Cycle Fatigue ◽

Thermal Crack ◽

Critical Crack Length ◽

New Device ◽

Railroad Wheels

This paper presents a method for the thermal crack evaluation of railroad wheel materials and the results. The research investigated the basic thermal crack resistance as a low cycle fatigue behavior in terms of Δεt-Ni and da/dN-ΔK. In order to be able to evaluate such material characteristics in service by experimentation, reproducible conditions such as similar stress-strain, temperature rise, and damage morphology are required. The methods proposed in the past for high temperature low cycle fatigue or thermal shock such as Coffin’s and Manson’s methods do not provide the above conditions at the same time for thermal cracks in railroad wheels. The material design to avoid such thermal damages has not yet been established. Therefore, a simple brake tester with a special device for measuring radial deflection converted into strain was designed and manufactured. The relations of Δεt-Ni and da/dN-ΔK, which have not been clarified for thermal crack behavior in railroad wheels, were obtained for wheel materials by experiment using this new device. To predict the life of a wheel, one must know the real service conditions from field measurements. Once the histogram of the initial brake speed, intensity of brake application, and number of brakings from the initial speed is obtained, the histogram can be converted into the relation of strain range and number of cycles. The calculation of cycles for crack origination and propagation is possible based on the experimental results on Δεt-Ni and da/dN-ΔK. From the material data of fracture toughness and possible residual stress value in the field, the critical crack length for wheel fracture can be then estimated, and the life from the cycles to the critical length is estimated. This method will provide the appropriate maintenance schedule to prevent wheel fracture.

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Recognition of defects from impact generated surface waves on the rim of a railroad wheel

The Journal of the Acoustical Society of America ◽

10.1121/1.2019492 ◽

1982 ◽

Vol 71 (S1) ◽

pp. S63-S63

Author(s):

M. Fahmy

Keyword(s):

Surface Waves ◽

Railroad Wheel

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Forging and Heat Treating Process Upgrades for a Wrought Railroad Wheel Manufacturing Facility

IEEE/ASME/ASCE 2008 Joint Rail Conference ◽

10.1115/jrc2008-63046 ◽

2008 ◽

Author(s):

George Ames ◽

Cameron Lonsdale ◽

John Leghorn

Keyword(s):

Heat Treating ◽

Rolling Process ◽

Railroad Wheel ◽

Hydraulic Systems ◽

Controlled Cooling ◽

Element Analysis ◽

Manufacturing Facility ◽

Computer Controlled ◽

Forging Press ◽

Quenching And Tempering

This paper describes a major capital project that was recently completed at a North American wrought railroad wheel manufacturing facility. The overall goals and concept of the project are outlined. Upgrades and improvements to band saws, the 10,000 ton forging press, rolling mill, and associated hydraulic systems, are described with emphasis on improvements in process speed. Installation of new wheel handling robots, which replaced an additional number of older, less robust wheel handling robots, is reviewed. Further, a new in-line wheel heat treating process, which provides for rim quenching and tempering of the wheel shortly after the forging and rolling process is completed, is described in detail. The new computer-controlled heat treating process features a rotary heating furnace to austenitize the wheels, several rim spray stations for quenching, a slot-in-the roof tempering furnace, controlled cooling operations, and automated Brinell testing. Important equipment maintenance concerns that were addressed are also reviewed. Finite element analysis (FEA) results for the new wheel heat treating process are discussed, along with other process considerations.

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