Estimation of amplitude and frequency dependent parameters of hydraulic engine mount given limited dynamic stiffness measurements

New procedures have been proposed to estimate frequency- and amplitude-sensitive parameters of hydraulic engine mounts that typically exhibit several nonlinearities. The estimation scheme utilizes refined modeling methods and is based on the premise that only limited measurements of the steady state dynamic stiffness (at the frequency of excitation) are available. Analogous mechanical models are constructed corresponding to the inertia track and decoupler induced resonances in the lower and higher frequency regimes respectively. By first implementing the estimation algorithm to fixed and free decoupler mounts (up to 50 Hz), key parameters (such as inertia-augmented fluid damping and decoupler gap length) are approximated and the effects of several system nonlinearities (such as vacuum-induced asymmetric chamber compliance and damping introduced by the decoupler switching action) are quantified. The dimension of the system is then increased to describe the dominant inertia effect at higher frequencies (from 50 to 300 Hz). Decoupler resonance related parameters such as its damping are estimated. Finally, the quasi-linear mount model with estimated parameters (on broad band basis) is efficiently and successfully used to predict the transient response to a realistic displacement excitation. Limitations of the proposed estimation method are also discussed.