Tie-Plate Cracking on Wood/Composite Ties: A Parametric Study

Abstract

Composite ties are commonly used as a replacement for wood ties because of many advantages. For example, composite ties show higher decay and corrosion resistance, greater compatibility with available fastening methods, and the ability to be inter-mixed with wood ties. However, recently, premature fatigue failures of tie plates installed on composite ties have been found at the TTCI test facility, while no failures had been found in tie plates installed on wood ties. This paper presents an investigation of tie plate failures using finite element analysis. A full-scale finite element model of the involved components—consisting of axle, wheel, rail, tie plate, and tie—is developed with an application of vertical and lateral loads on the axle. Three contact interfaces—between wheel-rail, rail-tie plate, and tie plate-tie, are defined to simulate actual operational configuration. To investigate the bending stresses in tie plates as a result of wheel-rail rolling contact, a parametric study of the elastic modulus of the ties, and the applied vertical and lateral wheel loads is examined. Results show that 1) given typical vertical and lateral loads, the decrease of tie’s elastic modulus increases transverse (bending) stresses at the base of the tie plate; thus, promoting high-cycle fatigue failures, and 2) in addition to the vertical load, the lateral loads also have a significant effect on the bending stress in the tie plate, 3) spike-hole cracking is the dominant mode of failure in composite ties operated under all simulated load cases, while edge failure is dominant in wood ties operated under a large lateral load.

On Hogging Bending Test Specifications of Railway Composite Sleepers and Bearers

“…When considering the deflected shapes, it is evident that none of standardized test methods can completely mimic in situ behaviors. This new finding is aligned well with other studies (Reiff et al, 2007;McHenry et al, 2008;Davis et al, 2009;Tangtragulwong et al, 2011;Kaewunruen et al, 2018;McHenry and Gao, 2018;Qian et al, 2019). When considering the purpose of performance benchmarking, it is apparent that the Australian test setup condition (AS1085.14) can better represent the hogging deformations at the mid span than the test provision of ISO standard (ISO 12856).…”

Fatigue analysis of railway wheel using a multiaxial strain‐based critical‐plane index

“…Due to heavy axle loads in locomotive industry, localized plastic deformation occurs at the wheel‐rail contact interface . Such a compressive deformation at running surface is balanced by tensile residual stresses at subsurface, which are found to play an important role in fatigue crack nucleation . The stress‐strain relationship for all the components in the FE model is defined using a plasticity model with both isotropic and kinematic hardening …”

“…Using stress‐strain plots of specific loading cycles, Ringsberg et al later used this optimization results to determine Chaboche model parameters and implemented it into ABAQUS material library to study FEA of rolling contact. Due to less complexity of the Chaboche plasticity model, it is more suitable for studying FEA of computationally intensive full‐scale wheel rail contact …”

“…On the other hand, the experimental determination of the wheel's material properties in terms of the utilized plasticity model is beyond the objectives of this study. Accordingly, the material properties and hardening parameters for pearlitic rail steel used in this study are given below:…”

“…The rolling of the wheel is performed in a distance of 70 mm with 1‐mm increments. A previously carried‐out FE study on the RCF of rails that uses the same wheel and rail profiles determined that this rolling distance was sufficient to capture the “full” stress/strain response that takes place during rolling at any component cross section. Therefore, in this study, the evaluation of the stress/strain response and of the modeled wheel is performed at a cross section located in the middle of the rolling trajectory of the wheel; that is, the wheel cross section that is most directly in contact with the rail once the wheel has been rolled a distance of 35 mm.…”