Comparative analysis of calculation methods for dynamic characteristics of hydraulic dampers

Dynamic stiffness and dynamic damping are the core performance indicators of hydraulic dampers, and their accurate characterization highly depends on the precise calculation of the phase angle between damping force and excitation displacement. Aiming at the problem that multiple phase angle calculation methods coexist in engineering practice with unclear applicability, six mainstream phase angle calculation methods based on the Maxwell model, namely, the EN method, DIN method, FFT method, TB displacement method, TB force method, and Mean method, are systematically reviewed and compared. According to the TB/T 1491—2015 standard, dynamic characteristic tests of single-circuit and double-circuit hydraulic dampers are carried out on a suspension element performance test bench, and the corresponding data are collected. The adaptability of different methods under damper unloading conditions, computational stability and applicability to different types of dampers are mainly investigated. The results show that the DIN method and TB force method are not suitable for damper unloading conditions due to their heavy dependence on the ideal elliptical shape of the force-displacement diagram; the EN method, TB displacement method, and Mean method rely only on a small number of characteristic point data and are susceptible to noise interference and the amplification effect of the arcsine function at low frequencies, resulting in large fluctuations in dynamic characteristic results. In contrast, the FFT method and DIN method use full-cycle data and exhibit excellent computational stability and noise immunity; the EN method requires good symmetry of the indicator diagram and is more suitable for double-circuit dampers; the FFT method cannot reflect the unloading state of double-circuit dampers and is more suitable for single-circuit dampers. In summary, the Mean method and TB displacement method should be preferentially adopted for double-circuit hydraulic dampers, while the FFT method is recommended for single-circuit hydraulic dampers.