Determining the angles of squat cracks via CT scanning and metallographic observations

Research output: Contribution to journalArticleScientificpeer-review

23 Downloads (Pure)

Abstract

This study investigates the angles θ1, θ2, and θ3 that squat crack faces form with respect to three orthogonal planes: the rail top, the longitudinal-vertical cross-section and the lateral-vertical cross-section. Rail samples with squats of various severities are obtained from the field. Their three-dimensional crack networks are reconstructed using CT (computed tomography) scanning and serial cutting. A 3D visualization method, together with the necessary geometric definitions, is developed for enabling effective measurement and characterization of the squat cracks. It is found that the cracks can be characterized by four orientations (T1 – T4). The variation ranges of the crack angles are determined for each orientation that satisfies 132° ≤θ1 ≤ 150°, 6° ≤θ2 ≤ 36° and 67° ≤θ3 ≤ 81°. By investigating the occurrence frequency of the orientations, it is found that T4 and T1 together form the primary V-shaped cracks of the squats, and T2 and T3 together form the secondary V-shaped cracks. A finite element modelling of the wheel-track system, in combination with contact mechanics and multi-axial fatigue analysis, successfully relates the stress state to the RCF cracks.

Original languageEnglish
Article number107016
Number of pages19
JournalEngineering Fracture Mechanics
Volume230
DOIs
Publication statusPublished - 2020

Keywords

  • Crack angle
  • Crack orientation
  • CT scan
  • Primary crack
  • Secondary crack
  • Serial cutting
  • Squat

Fingerprint Dive into the research topics of 'Determining the angles of squat cracks via CT scanning and metallographic observations'. Together they form a unique fingerprint.

Cite this