Modelling and dynamic properties of a novel solid and liquid mixture vibration isolator

Solid and Liquid Mixture (SALiM) vibration isolator is a new isolator which is designed for vibration isolation of heavy equipment with low frequency. The isolator contains liquid and elastic solid elements as working media. To get the stiffness property of the isolator, this paper establishes the mechanics model of elastic solid elements by introducing plate-shell model. Considering geometry nonlinearity, the stiffness of the element under outer liquid pressure and inner air pressure was obtained by perturbation method. Then the stiffness of isolator is derived. As a result, the stiffness is piecewise linear-nonlinear and determined by parameters of the elastic elements and elastic container. In addition, the equation of motion (EOM) of a single degree of freedom system supported by a SALiM isolator is given. The properties of the frequency response function (FRF) of the system are analysed using averaging method which is a classical approximation approach for estimating nonlinear system FRF. And it is found that the system with SALiM isolator shows softening stiffness behaviour. The jumping phenomenon clearly occurs under certain condition. Finally, the vibration isolation property is predicted based on energy transmissibility (ET) in different cases.