Self-excited yawing vibrations of railway cars

The site 1] presents a video recording of the motion of empty freight railway cars. The video demonstrates that some railway cars experience angular self-excited vibrations in the horizontal plane (i.e., yawing). In the same reference, the main causes of such a “negative dynamics” of railway cars are listed. All causes are related to some defects in railway car manufacturing. We show that such self-excited vibrations are possible even in the case of absolutely ideal railway car without any defects at all. It is shown that, for a certain combination of parameters, the rectilinear (unperturbed) motion of a railway car may experience flutter instability. This type of self-excited vibrations of railway cars has not been studied earlier 2, 3].