Acoustic signature processing for railroad wheel flat spot detection

This thesis is a study of the feasibility of detecting flat spots on railroad wheels. The principal method used was acoustic signature analysis of the vibrating rail. For this purpose an automatic system monitored by a mini-computer was tested. The results of tests show that the design of a detection system can be based on the periodicity of the impact of the flat spot on the rail or on the spectral analysis of the rail vibrations, or on both. At the present stage a system using the combination of the two methods was found to be most reliable. Several resonance frequencies found in the spectrum of rail vibrations are in approximate agreement with Timoshenko’s theory. The spacing between the ties appears to determine which vibrational modes are preferentially excited.