Experimental investigation of the vibration transmissibility of a magnet-spring vibration isolator under random excitation

A magnet-spring vibration isolator comprised of several magnets and mechanical springs has been proved to be highly effective for overcoming the major limitation of a conventional linear vibration isolator in such a way that the stiffness of the isolator is sufficiently large to hold the weight of a load, but becomes much softer under dynamic motion. The vibration transmissibility of this magnet-spring vibration isolator is usually examined using a sinusoidal excitation with a specific frequency because the system is nonlinear. In this paper, the isolation performance of the magnet-spring vibration isolator is further investigated experimentally for the case of random base excitation. The experimental results are compared with the cases of sinusoidal excitation obtained by computer simulations considering both jump-up and jump-down transmissibility curves. The results are interesting: the vibration isolation performance improves as the RMS (Root Mean Square) amplitude of the random base excitation increases; the experimental vibration transmissibility curve of the random excitation is bounded by the jump-up transmissibility curve of the corresponding sinusoidal excitation case.