Analysis of Frequency at Minimum Dynamic Stiffness for a Hydraulic Engine Mount with Floating Decoupler under high frequency excitation

The primary functions of mounts include providing structural support, sound insulation, and vibration damping. Dynamic stiffness and phase angle are critical metrics for evaluating their NVH (Noise, Vibration, and Harshness) performance. This paper examines a floating decoupler hydraulic mount featuring a long decoupling membrane channel. A nonlinear lumped parameter model is developed to calculate the dynamic stiffness and phase angle. The model incorporates fluid flow in the lower chamber and variations in the support reaction force of the decoupling membrane under switching conditions. Parameters of the nonlinear lumped parameter model, including rubber stiffness, equivalent piston area, and volumetric compliance of the fluid chamber, were analyzed and calculated using the finite element method. The influence of different decoupling membrane channel structures on the frequency corresponding to the minimum high-frequency dynamic stiffness was investigated based on the established model. The results demonstrate that, under high-frequency and small-amplitude conditions, increasing the decoupling membrane channel length and decreasing its cross-sectional area result in a lower frequency at which the minimum high-frequency dynamic stiffness occurs. Conversely, under low-frequency large-amplitude conditions, alterations in the decoupling membrane channel structure have negligible impact on the dynamic characteristics. A comparison between simulation and experimental results confirms that the developed lumped parameter model accurately represents the dynamic behavior of the hydraulic mount.