Introduction of falling friction coefficients into curving calculations for studying curve squeal noise

In this paper, a method of introducing falling friction coefficients into curving simulations for studying curve squeal noise is presented. Generation of squeal at the wheel of a railway vehicle in a curve is caused by unstable vibration, caused in turn by a lateral wheel/rail force which reduces with increasing lateral creepage. To model vehicle curve squeal, the wheel/rail tangential force in the curving simulation is calculated by a modified version of FASTSIM, which uses a sliding velocity-dependent friction characteristic. Using the falling friction characteristics, a UK passenger vehicle is modelled with SIMPACK. Curving behaviour is simulated for a range of curve radii and cant deficiencies. The wheel/rail contact properties are then obtained to study the possibility of the occurrence of squeal using a frequency-domain method. The methodology in this paper allows various curves, wheel/rail profiles, vehicle speeds and friction characteristics to be taken into account.