Curve squeal of urban rolling stock—Part 3: Theoretical model

After a brief literature review on friction-induced vibrations and rolling contact, a model of curve squeal generation is presented. Both tangential and normal wheel–rail contact forces as well as axial and radial wheel dynamics are taken into account. For initial conditions close to the quasi-static equilibrium, the squeal occurrence is predicted through the stability analysis of wheel modes (linear analysis). In unstable cases, the squeal level and spectrum are determined through the numerical study of limit cycles in the time-domain (nonlinear analysis). The model is used to study the effect of the friction–velocity relationship and the coupling between tangential and normal dynamics on the stability of the system, especially for large lateral offsets of the wheel–rail contact point. A parameter study is also performed. Results on critical angles of attack, critical wheel damping factors, excited wheel modes and vibration levels are presented. Finally, the results are compared with laboratory and field measurements and the validity of the model is discussed.