Modelling of High-Frequency Dynamic Stiffness of Double-Isolation Rubber Isolators

For traditional rubber isolators, the dynamic stiffness increases significantly with the increase of excitation frequency and will have a peak value, which is called "internal resonance" phenomenon. This paper investigates a double-isolation rubber isolator, which consist of two rubber bushings and additional mass. It can be applied to improve the NVH (Noise, Vibration and Harshness) performance at high frequency of electric vehicles. The equivalent mechanical model and mathematical model of the double-isolation rubber isolator are established. Then, the finite element analysis (FEA) model is established, and we calculate the drive point dynamic stiffness and cross point dynamic stiffness of the inner bushing, outer bushing and the entire double-isolation rubber isolator. The dynamic stiffness and additional mass of the inner and outer bushings are substituted into the mathematical model, and the derived dynamic stiffness of the double-isolation rubber isolator is consistent with the finite element result, which verifies the correctness of the equivalent mechanical model and mathematical model.