Fine interrelation between track irregularities and vehicle responses: multi-scale time-dependent correlation analysis

Abstract

Track irregularities are perhaps the main excitations of vehicle–track systems and cause dynamic wheel–rail responses, but track irregularities and vehicle responses do not always correspond to each other. In this study, the interrelations between track irregularities and vehicle responses in a multi-scale framework were investigated using measured data. Firstly, the track irregularity and vehicle response data were separated into modes on different time scales using multivariate empirical mode decomposition, and the energy distribution of each wavelength component was determined. Then, the local correlations between irregularity–response mode pairs were examined via time-dependent intrinsic correlation (TDIC) analysis. The irregularity–response interrelation was not always unique, but rather varied in both time scale and time domain, and positive–negative correlation reversals frequently occurred, causing a low overall correlation and coherence. TDIC analysis can elucidate the wavelengths and positions of track irregularities that affect vehicle responses.