00300668

Component

http://onlinepubs.trb.org...s/trr/1978/694/694-001.pdf

https://scholar.google.co...EELE&publication_year=1978

The objective of this study was the development of a computational model for the prediction of fatigue-crack propagation in rails under train-service loading. Constant-amplitude fatigue-crack-growth properties were determined for 66 rail steels. The effects of mean stress, temperature, and crack orientation were investigated. Variable-amplitude tests showed almost no load-interaction effects in fatigue crack growth in rail steels. Thus a linear integration scheme could be used for crack-growth prediction. Service-simulation tests were performed on the basis of four measured load spectra. The specimens were subjected to random loading, train-by-train loading, loading that used a sequence associated with 170 trains of six different types, and unit-train loading. The load sequence represented 0.9 million gross metric tons (1 million gross tons) of traffic and was repeated until failure of the specimens. Crack growth in the service-simulation tests could be reproduced by using the computational prediction model within a factor of 2 and within a factor of 1.5 in most cases. Discrepancies between predictions and tests results are partially due to the variability of crack-growth properties of rail steels. The way in which the prediction model can be used in a reliability analysis for failure-rate prediction is discussed. Such an analysis would allow management decisions with regard to the most cost-effective means to reduce failure rates of a given track. This is possible because the relative accuracy of the crack-growth prediction is expected to be better than its absolute accuracy.

Publication of this paper sponsored by Committee on Track Structure System Design. Distribution, posting, or copying of this PDF is strictly prohibited without written permission of the Transportation Research Board of the National Academy of Sciences. Unless otherwise indicated, all materials in this PDF are copyrighted by the National Academy of Sciences. Copyright © National Academy of Sciences. All rights reserved.

01411530

pp 2-10

1978

Transportation Research Record

030902840X

Print

Figures (17) ; References (4) ; Tables (2)

Cracking; Defects; Forecasting; Mathematical models; Rail steel; Railroad rails; Service life; Traffic density

Crack propagation

Bridges and other structures; Design; Highways; Railroads

TRIS, TRB

Sep 29 1979 12:00AM

• ANALYTICAL AND EXPERIMENTAL STUDY OF RESIDUAL STRESS IN RAILS
• BALLAST AND SUBGRADE RESPONSE TO TRAIN LOADS
• DEVELOPMENT OF MULTILAYER ANALYSIS MODEL FOR TIE-BALLAST TRACK STRUCTURES
• EFFECTS OF ENERGY-COST VARIATION ON FEASIBILITY OF ELECTRIFYING THE CINCINNATI-ATLANTA MAIN LINE OF THE SOUTHERN RAILWAY SYSTEM
• INTRODUCTION TO STRESSES IN RAILS: STRESSES IN MIDRAIL REGIONS
• MATHEMATICAL MODEL FOR LATERAL THERMAL BUCKLING AND DISPLACEMENT OF CURVED TRACK
• PERMANENT-DEFORMATION BEHAVIOR OF RAILWAY BALLAST
• STATISTICAL DESCRIPTION OF SERVICE LOADS FOR CONCRETE CROSSTIE TRACK
• TECHNIQUES FOR EVALUATING EFFECTS OF TRACK AND VEHICLE WEAR ON FREIGHT-CAR PERFORMANCE