Noise-related roughness of railway wheel treads-full-scale testing of brake blocks

2000 ◽  
Vol 214 (2) ◽  
pp. 63-77 ◽  
Author(s):  
M Petersson
Keyword(s):  
Cast Iron ◽  
Hot Spots ◽  
Testing Machine ◽  
Full Scale ◽  
Spatial Distributions ◽  
Material Transfer ◽  
Railway Wheel ◽  
Rolling Noise ◽  
Brake Block ◽  
Abrasive Property

Results from full-scale tread braking experiments on an inertia dynamometer (brake testing machine) are presented. Eighteen prototypes of brake blocks are investigated. Two braking characteristics relating to the influence of the blocks on the wheel tread are studied: generation of hot spots and generation of roughness (corrugation, waviness). Wheel tread temperatures are measured during braking using an infrared (IR) technique. The wheel roughness is measured after each brake cycle when the wheel has cooled down. A roughness indicator, RλCA, relates measured roughness to expected rolling noise as generated by the wheel in operation. A correlation between the spatial distributions of temperatures and roughnesses is normally found: stronger for cast iron blocks and composition blocks and weaker for sinter blocks. The cast iron blocks are found to produce high tread roughness levels, partly owing to material transfer from brake block to wheel tread. The composition blocks are found to result in lower roughness levels than the cast iron blocks. Finally, the sinter metal blocks are found to lead to the lowest roughness levels, a fact which is probably due to the abrasive property of these blocks. Friction coefficients during braking are also measured.

A STUDY ON THE FAILURE ANALYSIS OF CAST IRON BRAKE BLOCKS THAT ARE USED FOR RAILWAY APPLICATIONS

2006 ◽  
Vol 20 (25n27) ◽  
pp. 4535-4540
Author(s):  
CHANG-MIN SUH ◽  
BYUNG-WON HWANG ◽  
WOO-HO BAE
Keyword(s):  
Cast Iron ◽  
Hot Spots ◽  
Hot Spot ◽  
Frictional Heat ◽  
Failure Behavior ◽  
Surface Cracks ◽  
Element Analysis ◽  
Actual Application ◽  
The Matrix ◽  
Brake Block

In order to clarify the cracking and failure behavior of gray cast iron brake blocks that are used for the railway applications, macro- and micro observations regarding the cracks and the micro-structure of the used brake blocks were examined. Three brake blocks, which have different degrees of hot spots and cracking during the actual application, were selected for testing. In addition, a thermal-mechanical coupled finite element analysis (FEA) was applied to calculate the temperature and the stress field in the brake blocks during braking. As a result, it was observed that surface cracks were initiated at the hot spots and propagated into the matrix. From the observation of dispersed graphites close to the crack path, it can be said that the deterioration of materials due to the frictional heat of braking made it easy to initiate cracks at the hot spot. The hardness of the brake block was recommended to be under 85 by the Rockwell B scale in order to prevent hot spots and crack initiation. From the FEA, the procedure for the occurrence of hot spots and cracks was successfully simulated by assuming the surface roughness on the slid surface of the brake block.

scholarly journals The Roseville Bomb Disaster Simulated Train Braking System Tests and Boxcar Wood Floor Ignition Experiments

1991 ◽  
Vol 113 (1) ◽  
pp. 91-99
Author(s):  
B. Ross ◽  
P. G. Parikh
Keyword(s):  
Heat Flux ◽  
Cast Iron ◽  
Ignition Time ◽  
Thermal Response ◽  
Radiant Heat ◽  
Full Scale ◽  
Test Facility ◽  
Shield Effectiveness ◽  
Wood Floor ◽  
Wood Surfaces

A massive chain of property damaging explosions involving an ammunition train occurred at the railroad yard, Roseville, California. The train had pulled into the yard after a night trip of some 100 miles across Donner Summit and down the extended Norden-Roseville grade. Physical evidence confirmed that first explosions were centered at a DODX type boxcar loaded with 250 lb. bombs. Further, bomb cook-off detonation tests established that the triggering bomb blast was not a result of shock loads but rather derived from an engulfing fire initiated in the boxcar wood plank floor under influence of extended heavy braking action on the mountain grade. It was also suspected that high friction composition brake shoes were fitted on the car as replacements for cast iron shoes but the brake mechanical linkage lever ratios had not been modified as required. Results of a comprehensive research program are presented within context of the explosion event, and include analytical computer simulation of train descent profiles on mountain grades through full scale dynamometer tests with actual rail wheels and ultimately more scientific scaled wood floor ignition experiments in the laboratory. The thermal response of a simulated DODX boxcar wood floor was studied through experiments, full scale at a rail wheel dynamometer test facility, and in the laboratory. Certain input data for the wood floor ignition test program were measured on an actual boxcar joined with a freight train consist in transit down the Norden-Roseville grade. Two series of scaled wood ignition experiments were conducted on simulated DODX boxcar floors. Objectives of these tests were to determine: Influence of a cooling air stream on the ignition behavior of radiantly heated wood surfaces, and effectiveness of DODX (stand-off) and AAR (flush) type spark shields in preventing ignition of wood surfaces under radiant heating. It was found that for radiant heat flux levels representative of high friction composition shoes under severe train braking conditions, low speed airflow (wind) exerts a dramatic influence on the wood ignition time. For example, average ignition time for a simulated boxcar floor at a heat flux level of 0.4 cal/cm2sec was determined to be 15.6 min. with a 5 mph wind as compared to 3.6 min. with no wind. In the spark shield effectiveness tests, conducted at heat flux levels representative of cast iron shoes under severe braking conditions, the DODX (stand-off) type spark shield failed to prevent spontaneous flaming ignition of a wood surface directly above it. Under identical conditions, no flaming ignition was encountered with the AAR (flush) type spark shield.

Rail Vehicles Brake Components Test Bench Utilisation

2013 ◽  
Vol 486 ◽  
pp. 379-386 ◽  
Author(s):  
Juraj Gerlici ◽  
Tomáš Lack
Keyword(s):  
Cast Iron ◽  
Friction Coefficient ◽  
Test Bench ◽  
Rolling Contact ◽  
Friction Materials ◽  
Braking System ◽  
Rail Vehicles ◽  
Type K ◽  
Technical Solutions ◽  
Brake Block

Reduction of noise due to rolling contact of wheel and rail for fright cars is one of the principal tasks of the European railways to be solved. Experts of railways, industries and universities were engaged during the last about ten years to search for technical solutions. An important noise reduction of fright cars can be achieved by replacing the cast iron brake shoes by composite brake shoes. Doing that, two directions have been taken into consideration. This is due to the fact, that at that time most composite brake shoes were based on friction coefficients were far away from that ones of the cast iron brake shoes. Applying such friction materials on existing vehicles would have as a consequence the change of braking forces acting on the wheels. These types of brake shoes (K-block) show a friction coefficient which is higher than that one of cast iron. As a consequence the application of the silent composite brake blocks of type K affords the adaptation of the braking system of the vehicle, what is cost intensive. For these reason, the application of K-brake block was proposed for new built vehicles. For existing vehicles solutions having the same friction coefficient as the cast iron brake shoes were requested (LL-Brake doing in this way, the modification of the braking equipment of existing fright cars could be avoided.

Simulation of Cylinder Bore Surface Finish Parameters to Improve Laboratory-Scale Friction Tests in New and Used Diesel Oil

2001 ◽  
Author(s):  
Peter J. Blau
Keyword(s):  
Cast Iron ◽  
Surface Finish ◽  
Testing Machine ◽  
Cylinder Liner ◽  
Laboratory Scale ◽  
Engine Oil ◽  
Wear Testing ◽  
Average Roughness ◽  
Arithmetic Average ◽  
Cylinder Bore

Abstract The development of alloys, coatings, surface treatments, and lubricants for improved cylinder liners and rings has historically included friction and wear testing. The correlation of results from motored engines or laboratory-scale tribotests with those from full-scale, fired engines remains a subject of contention. Attempts to develop valid engine wear simulators have met with varying degrees of success. Complexities in understanding and duplicating the relevant contact conditions in fired engines have challenged the designers of sub-scale, simulative laboratory tests. The current paper describes one aspect of this problem; namely, simulating the cylinder bore surface finish for use in bench tests. A rapid method to prepare cast iron test specimens that have similar surface roughness parameters to a production cast iron cylinder liner has been developed. To compare the sliding response of simulated liners with actual liners, cast iron specimens were friction-tested in both new and used 15W40 commercial diesel engine oil, in mineral oil, and without liquid lubrication. A reciprocating, ball-on-flat testing machine was used with test lengths that ranged from 100 to 20,000 cycles. Kinetic friction coefficient data compared favorably between the simulated cylinder liner specimens and actual cylinder liner segments. The friction coefficients obtained in tests with different lubricants on the simulated surfaces were related through a second-degree polynomial to the change in arithmetic average roughness that occurred during running-in. Additional elements of the fired engine environment will be added in the next stages of this research to determine the degree of complexity that is needed to obtain increasingly better simulations.

Study on Tribology Characteristic of the Cast Iron Friction Pair in the Self-Repairing Additive and Mechanism Analyzing

2011 ◽  
Vol 239-242 ◽  
pp. 1896-1900
Author(s):  
Yan Hong Yan ◽  
Yu Lin Yang ◽  
Nan Wang
Keyword(s):  
Cast Iron ◽  
Friction Pair ◽  
Testing Machine ◽  
Great Influence ◽  
The Self ◽  
Wear Testing ◽  
Wear Characteristics ◽  
Remarkable Effect ◽  
Frictional Wear ◽  
Self Repair

Influence of frictional wear characteristics of the cast iron-cast iron friction pair were investigated in the Self-repairing Additive with different concentration by using MMU-5G end-face friction and wear testing machine. The capability of generating self-repair coatings on the cast iron tribo-surface was verified in the Self-repairing Additive. The surface images of friction pair and their chemical composition were detected by using SEM and EDS. The result indicates different concentration has a great influence on frictional wear characteristics of friction pair in the Self-repairing Additive. In the self-repairing Additive, the Self-repair coatings are not formed on the cast-iron worn surface; self-repairing Additive has remarkable effect on antifriction and wearing of cast iron.

3211 Brake Performance of Cast Iron Composite Brake Block Containing Carbon Nanotube Alumina Filters

2011 ◽  
Vol 2011.20 (0) ◽  
pp. 201-202
Author(s):  
Naoya FUJIWARA ◽  
Toru MIYAUCHI ◽  
Jun-ichi NAKAYAMA ◽  
Bunshi FUGETSU ◽  
Hiroyuki NISHIMURA
Keyword(s):  
Cast Iron ◽  
Carbon Nanotube ◽  
Brake Performance ◽  
Brake Block

scholarly journals Estimating Passive Stress Acting on a Grain Entrapment Victim’s Chest

2018 ◽  
Vol 24 (3) ◽  
pp. 113-126
Author(s):  
Salah F. Issa ◽  
Carl Wassgren ◽  
Charles V. Schwab ◽  
Richard Stroshine ◽  
William E. Field
Keyword(s):  
Stress State ◽  
Testing Machine ◽  
Full Scale ◽  
Experimental Results ◽  
Testing Device ◽  
Active Stress ◽  
Farm Safety ◽  
Passive Pressure ◽  
Criterion Testing ◽  
Passive Stress

Abstract. Grain entrapments remain a major concern in the grain industry, with 1,100 incidents documented since the 1970s. One particular concern is the ability of a victim to breathe while entrapped in grain. Anecdotal reports suggest that victims struggle to breathe when entrapped in grain to a depth that covers their chests, yet some evidence indicates that victims should be able to breathe normally as long as their airways are not blocked regardless of depth. The hypothesis for this discrepancy is that previously published experiments measured an active stress state in the grain, while a person breathing also experiences a passive stress state during inhalation. The passive stress is significantly larger than the active stress. The objective of this study was to measure the passive stress when pushing against grain, such as during inhalation, and compare it to active stress state measurements. An MTS Criterion testing machine, which is a force deformation testing device, was used to push a block horizontally against a column of grain and record the force and displacement during the movement. The measured passive stress was calculated from the force and displacement values and ranged from 9.4 to 11.0 kPa at a depth of 20 to 30 cm. These values are three to four times larger than previously published measurements of stresses at similar depths. This result indicates that the discrepancy between experimental results and anecdotal reports is most likely due to the type of stress state experienced in grain entrapment. Findings imply that the pressures on the victim’s chest during entrapment are sufficient to cause breathing difficulties or crush/positional asphyxiation in some cases. A full-scale study is recommended. Keywords: Active pressure, Corn pressure, Farm safety, Grain rescue, Passive pressure, Rib cage.

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