Mathematical Modeling and Dynamic Optimization of Liquid-Damped Mounts for High-Frequency Vibration Isolation

Traditional liquid-resistive mounts are widely used in vehicle powertrain vibration isolation because of their favorable low-frequency damping characteristics. However, they usually suffer from pronounced high-frequency dynamic stiffening, which significantly degrades their vibration-isolation performance in the high-frequency range and remains a critical limitation in passive mount design. To address this problem, this study presents the systematic modeling, comparative analysis, and structural optimization of liquid-resistive mounts with different internal configurations. Three representative mount structures, namely the decoupler-membrane type, the conventional bell-plate type, and a novel bell-plate configuration, are first described in terms of their structural characteristics and working mechanisms. Based on the lumped-parameter method, mathematical models of the three mounts are established, and their low- and high-frequency dynamic characteristics are comparatively investigated. The vibration isolation performance of the mounts is further evaluated under various excitation conditions to clarify the influence of structural modifications on the dynamic response and transmitted force. In addition, sensitivity analysis is performed using the ISIGHT software platform (ISIGHT 5.6 Design Gateway) to identify the key parameters governing high-frequency performance. Subsequently, structural optimization is conducted using nonlinear programming under the quadratic Lagrangian algorithm and the Six Sigma method. The results indicate that the introduction of a bell plate has little influence on the low-frequency dynamic characteristics, while it effectively suppresses high-frequency hardening and improves high-frequency vibration isolation. Moreover, the Six Sigma optimization method achieves better performance improvement than the NLPQL approach, providing a useful reference for the design and optimization of passive liquid-resistive mounts.