Numerical Modelling of Nonlinear Vibration Isolation System Free Oscillations

The article deals with numerical analysis of nonlinear vibration isolation system free oscillations. According to the latest recommendations [1], vibration isolation of precision equipment should be effective over the 1 – 100 Hz range [2]. This fact sets a challenge to develop a sub-herz vibration isolator. Such vibration isolators with 0.5 Hz natural frequency have been developed in latest works [3,4]. For mathematical representation of such a dynamical system, elastic characteristic should be approximated with a polynomial. In this paper, we consider the approximation of elastic characteristic by means of 5th and 7th order polynomials. This leads to numerical solution of nonlinear dynamic equations. We construct the solution of such equation on the phase plane and determine equilibrium points. The stability of the equilibrium points is investigated using linearization technique. The law of the isolated mass oscillations is derived from numerical solution of the dynamic equation by means of Dorman – Prince 4(5) and 8(7) solver and the system’s natural frequencies are calculated using the FFT technique.