Optimum control of vibration and structure-borne noise for machinery on flexible foundation

Faced with the key problems of machinery-induced vibration and structure-borne noise when dynamic machines are mounted on flexible foundations such as upper floors of factory buildings, the vibration and noise transmission mechanism and optimal control for the flexible system are systematically studied by the novel approach of power flow. A more general system of machinery-isolators-flexible foundation is modelled. Based on substructure transfer matrix technique the power flow input and transmitted are formulated in closed forms, and the effects that the flexibility of foundation and the asymmetricity of system have upon the power flow transmission spectra are revealed. Also the inverse problems of isolation design are discussed by using an optimum method. Optimum design for a typical example about a force fan mounted on a concrete building floor is successfully performed to show that the model is practical, the theory and the optimization developed are reasonable and effective. Thereby, theoretical bases for accurate prediction of isolation effectiveness and an optimum method for practical design of a general flexible isolation system are provided.