Research on the influence of passenger flexibility on carbody vibration of high-speed vehicles

Carbody vibration in high-speed vehicles significantly impacts ride comfort and operational safety. Conventional dynamic analyses often simplify passengers as rigid masses, neglecting the influence of body flexibility on carbody dynamics. This study systematically investigates the effect of passenger flexibility on carbody vibration through numerical simulation, mechanistic modeling, and laboratory tests. A validated multi-body dynamics model of a human-vehicle coupling system is established to evaluate vibration responses under various speeds. A simplified analytical model is further developed to reveal the underlying mechanism. Experimental tests are conducted to corroborate the theoretical and simulation results. The results show that passenger flexibility consistently attenuates vertical vibration across all speeds, whereas laterally, it suppresses vibration at low speeds but amplifies it at high speeds. Mechanism analysis reveals that the passenger acts as an additional mass functioning like a dynamic vibration absorber. The difference in modal frequencies between lateral and vertical directions defines distinct vibration absorption bands. While vertical excitation remains within this band, ensuring continuous attenuation, lateral excitation at high speeds exceeds it, reducing the equivalent carbody mass and amplifying vibration. This study enhances the understanding of passenger dynamics in railway vehicles and refines the comprehension of human-vehicle interaction mechanisms.