A Lumped Parameter Model Concerning the Amplitude-Dependent Characteristics for the Hydraulic Engine Mount with a Suspended Decoupler

This paper presents a novel lumped parameter model(LPM) and its parameter identification method for the hydraulic engine mount(HEM) with a suspended decoupler. In the new model the decoupler membrane’s variable stiffness caused by being contact with the metallic cage is considered. Therefore, the decoupler membrane in the model can be taken as a spring. As a result, two parameters of the decoupler’s variable stiffness and the equivalent piston area are added. Then the finite element method is employed to analyze the suspended decoupler membrane’s variable stiffness characteristics under the contact state with the metallic cage. A piecewise polynomial is used to fit the decoupler membrane’s variable stiffness. To guarantee the symmetry of the stiffness, the polynomial only keeps the odd power coefficients. The other lumped parameters of the HEM, such as the elastic stiffness and equivalent piston area of the rubber spring, volumetric compliance of the fluid chamber, the fluid inertia and resistance of the inertia track are also identified with the finite element method for further numerical simulations. Finally a computer simulation under sinusoidal excitations of various amplitudes is carried out with the identified lumped parameters to obtain the dynamic characteristics of the HEM. The validity of the LPM is also experimentally verified with the same configuration. The results show that with the identified lumped parameters, the proposed LPM can accurately predict the amplitude-dependent dynamic stiffness and loss angle of HEM with a suspended decoupler, while the conventional LPM, by not considering decoupler membrane’s variable stiffness characteristics, cannot accurately reflect the dynamic characteristic this kind of HEM.