An investigation into the causes of squats—Correlation analysis and numerical modeling

• Published in: Wear 2008-10, Vol.265 (9), p.1349-1355
• Main Authors: Li, Zili, Zhao, Xin, Esveld, Coenraad, Dollevoet, Rolf, Molodova, Marija
• Format: Article
• Language: English
• Subjects: Applied sciences; Exact sciences and technology; Finite element analysis; Friction, wear, lubrication; Fundamental areas of phenomenology (including applications); Impact; Machine components; Mechanical contact (friction...); Mechanical engineering. Machine design; Physics; Rolling contact fatigue; Solid mechanics; Squat; Structural and continuum mechanics; Track irregularities; Vehicle–track interaction
• ISSN: 0043-1648; 1873-2577
• DOI: 10.1016/j.wear.2008.02.037

Nowadays squats are a severe rolling contact problem on some railways. The root causes of it are not yet clear. From railway operation and maintenance points of view, root causes have to be known so that effective maintenance policies and plans can be made based on measurements and prediction. In the present work first a correlation analysis is performed based on measured data and field observations, and then a relation between squat occurrence and some parameters of the vehicle–track system is identified. Subsequently a transient finite element model of vehicle–track interaction is built up to analyze the contact forces and the resulting stresses and strains. The numerical results show good correspondence with observed phenomena at squats, and suggest certain relation between squat development and some eigen frequencies of the coupled vehicle–track system. A squat growth process is accordingly postulated.