The mechanisms of curve squeal

Existing curve squeal theory is often contradicted by field observations such as the generation of squeal from the outer wheel (including wheel flange contact), squeal occurring at various wheel natural frequencies, coupled rail vibrations when squealing wheels pass, and the obvious influence of trackform on squeal occurrence and severity. This paper discusses the deficiencies of existing theory and explores an alternative mechanism based on the concept of mode coupling instability which shows a better match with field observations from some sites.