Equivalent conicity for asymmetric wheel wear: a shift-based method for enhanced railway vehicle dynamics prediction

Conventional equivalent conicity methods, including the harmonic method and UIC 519, calculate the wheelset equilibrium position separately for each lateral displacement amplitude when determining equivalent conicity for asymmetric wheel profiles, resulting in amplitude-dependent integration ranges. This study proposes a shift-based equivalent conicity method in which the wheelset centre position is fixed directly based on the left-right wheel diameter difference. Equivalent conicity curves are then obtained by integrating the rolling radius difference over displacement ranges corresponding to different amplitudes while keeping this centre position fixed. To evaluate the proposed method, two sets of symmetric wheel profiles are inversely reconstructed from equivalent conicity curves obtained using the conventional and shift-based methods. Vehicle dynamics simulations, including bogie lateral acceleration, Sperling ride index and critical hunting speed, compare the dynamic behaviour of the reconstructed profiles with that of the original asymmetric wheel profile. The results indicate that both methods reproduce the dynamic characteristics under low wear, while at higher wear the shift-based method shows slightly closer agreement. The proposed approach also improves computational efficiency, reducing calculation time from approximately 2 s to 0.4 s, providing an efficient alternative for rapid equivalent conicity evaluation..