Transient Responses of Hydraulic Engine Mounts Using Linear and Nonlinear Models

Copyright © 2007 SAE International Competing linear, quasi-linear and non-linear hydraulic mount formulations of fixed and free decoupler types are comparatively evaluated for transient responses. First, features of the realistic excitation conditions are addressed. For instance, the mean load itself may vary with time, and several sinusoidal or transient excitations may be simultaneously present. Second, a multi-staged top chamber compliance model is proposed to capture asymmetric transient responses given step-up (-down) excitations. Third, implicit excitations introduced by the decoupler switching mechanism are identified at the odd harmonics of the explicit excitation frequency. Fourth, discontinuous model of bottom chamber compliance is proposed depending on the operating point(s) and/or dynamic loading. Some of the discrepancies observed between prior models and measurements can be explained using new models