Comparison of evaluation methods for the dynamic characteristics of railway hydraulic dampers

The EN and Area methods are commonly reported procedures for evaluating dynamic damper characteristics, both predominantly relying on time-domain data of damper force and displacement, with the EN method established as a standard in EN13802. However, these time-domain approaches do not fully utilize all experimental data and have inherent limitations that can impact the accuracy of the results. To address this challenge, this study introduces a calculation method based on the Fast Fourier Transform (FFT), which shifts the analysis from the time domain to the frequency domain, allowing for more reliable determination of phase angle, dynamic stiffness, and damping. Comparative analysis of dynamic test results on typical hydraulic dampers reveals that traditional time-domain methods lead to abnormal fluctuations in dynamic stiffness at low frequencies due to inaccuracies in phase angle calculations. In contrast, the frequency-domain method delivers more reliable results. Among the tested methods (EN, Area, and FFT), the FFT method aligns most closely with the standard EN method, showing discrepancies of less than 10%, and demonstrates greater robustness under noisy conditions. In comparison, the Area method exhibits higher sensitivity to sampling frequency variations, resulting in less reliable outcomes. This study provides practical insights for enhancing damper performance evaluation and recommends the frequency-domain method as a reliable tool for dynamic characteristic analysis, particularly in applications where noise resilience is required, while the EN method remains suitable for low-noise conditions.