Dynamic Performances of a Double-Layer Vibration Isolation System: Nonlinear Modeling and Experimental Validation

This work aims to identify ways to achieve dynamic performances of a novel double-layer vibration isolation system (DL-VIS) capable of achieving multi-directional isolation and extreme environmental adaptability. A forward modeling approach applicable to complex systems has been developed and analyses of nonlinear dynamic characteristics under different working conditions are performed. First, by integrating with constitutive models in terms of individual elastic elements and the connective relationships within the structure, multidirectional constitutive models for isolation devices are established. Further, the decomposition of linear and nonlinear stiffness components in different directions is performed using the Taylor expansion method. Subsequently, the dynamic response under sinusoidal sweep frequency loading is obtained using the related stiffnesses in the dynamic model and adopting the extended harmonic balance method. The effects of stiffness, damping, and a nonlinear stiffness gradient on the DL-VIS response are thoroughly evaluated. Finally, the vibration isolation performance and nonlinear dynamics under different working conditions are examined, and the proposed dynamic model is experimentally validated. The results indicate that the response of DL-VIS varies significantly under different working conditions, particularly under overload conditions. The nonlinear characteristics lead to wide-band instability near the natural frequency and excellent vibration attenuation performance in multiple directions. The theoretical model agrees well with the experimental results in the nonresonant region and near the first resonant peak, which proves the prediction accuracy in the low-frequency range. These findings provide robust theoretical and technical support for the design and performance optimization of isolation systems. © 2024 The Author(s). International Journal of Mechanical System Dynamics published by John Wiley & Sons Australia, Ltd on behalf of Nanjing University of Science and Technology.