Finite Element Analysis of the Effects of Bolt Condition on Bolted Rail Joint Stresses

Abstract

The rail joint is typically considered to be one of the weakest locations in the track superstructure. Defects and failures—including bolt hole cracks, head–web cracking or separation, broken or missing bolts, and joint bar cracking—have been found to start at rail joints and the area surrounding these joints. The initiation and propagation of these defects are primarily attributable to the discontinuities of both geometric and mechanical properties in the rail joint area and the high-impact loads induced by the discontinuities. Loosened or missing rail joint bolts can decrease the overall stiffness at the joint. A loosened rail joint can also accelerate certain types of defects, such as cracking around the bolt hole and the head–web fillet area (the upper fillet area) close to the rail end. These cracks present both economical and safety concerns as they can significantly reduce the service life of the rail or joint bar and even lead to breaks in the rail. However, the effect of bolt condition on stress propagation around bolted rail joints is not thoroughly understood. This study investigated the effects of bolt loading and missing-bolt configurations on the stress distribution at the bolt hole and the upper fillet area under static loading conditions. A comprehensive parametric analysis was performed with finite element modeling. Preliminary results showed that when bolt loading increased, the rail vertical displacement and stresses on the rail upper fillet decreased, but the stresses on bolt holes increased. The two center bolts, which were closest to the rail end, were the most sensitive bolts in terms of variation in stresses in response to changes in bolting and torqueing.

Fatigue Analysis of Rail-Head-to-Web Fillet at Bolted Rail Joint Under Various Impact Wheel Load Factors and Support Configurations

“…The static wheel load of 16,500 lb per wheel was provided by NYCTA as well. The wheel load position was determined based on previous research conducted at UIUC, which indicates that the rail end upper fillet stress reaches its maximum value when the wheel is at the rail end [13].…”

“…The key output for this parametric study is the estimated fatigue life at rail end upper fillet area. Details of the FE-based parametric analysis and parameters listed in Table 1 have been provided elsewhere [13].…”

“…The fatigue analysis procedure used in this study is illustrated in Figure 6. First, the stresses calculated from the FE-based parametric analysis [13] using Abaqus are required, and they play a key role on obtaining rational estimated fatigue life.…”

“…Loading history defines the stresses that the structure experiences during the fatigue analysis, which normally consists of the stresses calculated from FE analysis with a load factor function. The stresses applied in this fatigue parametric study have been obtained from previous study [13] and can be input directly into fe-safe. Those stresses would be utilized as the base load, and could be factored using a load factor function.…”

Effect of easement geometry on rail end fillet stress at bolted rail joints for transit track

“…A model designed specifically to study rail joints was previously developed by the research team to investigate the joint bar bolt condition, bar length, contact profile, and wheel speed. [8][9][10] The same model was utilized and tailored to investigate the effect easement profile in this study. 100-8 rail and AREMA standard joint bars (SB) 9 were selected to represent typical jointed track used in rail transit systems in the United States while the prototype joint bars (PB) provided another baseline.…”