United States Department of Transportation
i
Propagation Analysis of Transverse Defects Originating at the Lower Gage Corner of Rail
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1998-12-01
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[PDF-2.68 MB]
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Abstract:This report describes analyses performed to examine the growth rate of a particular transverse defect that forms in the rail head. The most common transverse defect found in rail, known as the detail fracture, has been studied in previous work. The present analyses, however, focuses on another internal transverse defect which originates at the lower gage corner of the rail head and has not been examined previously. This defect has been provisionally named "reverse detail fracture" because its origin is in the lower gage corner rather than the upper gage corner where detail fractures have been known to occur. The growth rate of reverse detail fractures is examined by modifying a model previously developed to analyze detail fractures. These modifications and other details of the analyses are described in this report. Using this model, sensitivity studies were conducted to examine the effect of various service conditions on the propagation life of reverse detail fractures. In addition, an approximate method to examine the effect of wear on rail stresses is described in this report. Wear is assumed to occur by a uniform loss of material from either the top of the rail or from the gage-side face. The approximate method is used to examine the effect of wear on propagation life. The results of the analyses indicate that the safe crack-growth life of reverse detail fractures is about 20% shorter than that for ordinary detail fractures under the same conditions. This suggests that the inspection interval should be reduced for rails where reverse detail fractures are expected to occur. The results also indicate that residual stress, thermal tension, and wear have a relatively strong influence on reducing the safe crack-growth life of reverse detail fractures.
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