Modeling of a stiffness-varying hydraulic bushing for enhancing hunting stability and curve-passing performance of railway vehicles

The hunting stability and curve-passing ability of railway vehicles are inherently contradictory problems, and hydraulic bushings can effectively improve these contradictions due to their strong nonlinear characteristics. This paper presents a refined nonlinear mechanical model for hydraulic bushings, incorporating both frequency-dependent and amplitude-dependent stiffness characteristics, based on their structural parameters and operating principles. The model is developed by combining a rubber spring model, an inertia channel model, and a volume flexibility model to capture the complex dynamic characteristics of the bushing. To validate the model’s accuracy, dynamic characteristic experiments are performed on hydraulic bushings using a suspension component performance test bench. The experimental results show good agreement between the simulated dynamic stiffness and equivalent damping values and the measured data. The proposed model is then integrated into vehicle dynamics simulations to evaluate the impact of hydraulic bushings on vehicle stability and curve-passing performance. Compared to traditional rubber bushings, vehicles equipped with hydraulic bushings demonstrate a significant increase in nonlinear critical speed on straight tracks and improvements in wheelset yaw angle and lateral wheel force when passing through curved tracks. These results highlight the ability of hydraulic bushings to effectively enhance both vehicle stability and curve-passing performance, offering potential advantages in vehicle suspension design.