Application of the Failure Assessment Diagram approach for contact fatigue damage evaluation in railway wheel steels

Abstract

A Failure Assessment Diagram (FAD), developed for rolling contact, was specifically formulated for railway wheel steels. The FAD allows combining a multiaxial fatigue criterion with the linear elastic fracture mechanics concept; in particular, it was used to assess the fatigue failure in wet contact, related to the pressurization of the fluid entrapped in surface cracks. The approach was applied to the results of previous bi‐disc tests carried out on three railway wheel steels, subjected first to a dry rolling‐sliding contact step, then to a wet contact step. The crack size distribution after the dry contact step was evaluated by a statistical approach; subsequently, the stress intensity factor during the wet contact step was estimated by finite elements. The results of the FAD agreed with the damage observed on the cross section of the specimens at the end of the tests. Furthermore, the FAD was used to determine the maximum allowable crack to prevent rolling contact fatigue, this way showing its potential as a damage tolerant approach.

Interior crack initiation during the very‐high‐cycle fatigue of railway wheel steel under axial loading and rolling contact loading

“…1,2 With the increasing running speeds and axle loads in modern railways, a new challenge of shattered rims is posed to the wheel/rail pair. 3,4 Shattered rim is a form of rolling contact fatigue caused by subsurface and interior crack initiation. [5][6][7][8] In general, fatigue life of shattered rim was usually more than 10 7 cycles, indicating a typical VHCF under rolling contact loading.…”

“…The new research topic of very‐high‐cycle fatigue (VHCF) is drawing increased attention because many engineering components, such as high‐speed railway wheels, turbine blades, and automobile cylinders, require 10 8 or even more loading cycles for safe performance 1,2 . With the increasing running speeds and axle loads in modern railways, a new challenge of shattered rims is posed to the wheel/rail pair 3,4 . Shattered rim is a form of rolling contact fatigue caused by subsurface and interior crack initiation 5–8 .…”

Study of stress intensity factors in sliding and tearing modes for subsurface elliptical cracks in rolling train wheels

“…They found that these cracks can be approximated as an ellipse with a diameter ratio of 2.5 to 7. Donzella et al 13 used a specified failure assessment diagram approach for the railway wheel steel to assess fatigue life prediction in wet contact conditions. Their numerical results were in agreement with the observed damages in cross‐sections of the samples.…”

Influence of wheel out‐of‐roundness on the remaining life of railway wheels under mixed‐mode fatigue loading

“…Many studies on crack propagation and fatigue analysis have been conducted. [9][10][11][12][13][14][15][16][17] Sajjadi et al 18 put forward a new brittle fracture criterion to predict the fracture in sharp V-shaped notches considering the influence of tangential stress and shear stress, which can effectively describe the situation where mode II load is dominant. Peixoto and de Castro 9 established a two-dimensional, wheel-rail contact, finite element model and discovered that the crack growth mode of the wheel rim is II or I-II mixed crack propagation mode dominated by shear stress.…”

“…Nejad et al 13 analyzed the influence of mechanical loads and stress fields during heat treatments on rim crack growth by establishing a three-dimensional, wheel-rail contact, finite element model to be combined with stress history to calculate mode I, II, and III stress intensity factors at the crack tip, as well as the wheel fatigue life. Donzella et al 14 proposed a calculation procedure for assessing mixed mode crack propagation and applied the procedure to railway wheels.…”