DESIGN OF EXCITATION SIGNALS FOR THE RESTORING FORCE SURFACE METHOD

In the classical Restoring Force method the non-linear force, acting on a mechanical system, is fitted to a series of standard functions. In order to guarantee the quality of the fit a sufficiently uniform distribution of the state trajectory sample points over the state plane is needed. In this paper, it is shown that a uniform covering of the state plane can be obtained using a periodic kinematic signal (i.e. displacement, velocity and acceleration) with a user specified amplitude spectrum by making a proper choice for the associated phases. These periodic kinematic signals can be imposed on the mechanical structure by implementing a software feedback which corrects the excitation force spectrum iteratively. In this paper it will be shown how to optimise the phase spectrum so that a uniform coverage is obtained.