This study presents an innovative hermetic squeeze film damper (HSFD), designed to provide superior damping in high-power equipment bearing systems. A comprehensive investigation is conducted to elucidate its nonlinear dynamic characteristics. A theoretical model incorporating the laminar entrance effect in the fluid annulus clearance is developed and validated through experimental excitation tests. The hysteretic behavior of the pressure differential force is systematically examined across key parameters, including annulus geometry, fluid film thickness, excitation frequency, and silicone oil properties, and the evolutionary mechanisms of the resulting nonlinear elastic and damping forces are revealed. Results show that considering the laminar entrance effect significantly enhances the pressure differential and elastic forces. Furthermore, the nonlinear elastic and damping forces exhibit clearly distinct and parameter-dependent variation trends.
Zhang et al. (2026) studied this question.