Developments of the indirect method for measuring the high frequency dynamic stiffness of resilient elements

The complex stiffness of resilient elements is an important parameter required in order to model vibration isolation for many applications. Measurement methods are being standardized which allow such a stiffness to be measured as a function of excitation frequency for known loading conditions. This paper describes one such method, the direct method, in which the resilient element is placed between two large blocks, the vibrations of which are measured. A number of refinements to this method are proposed here. These aspects of the method are then illustrated by using example results of measurements on a resilient rail pad for use in railway track. It is shown how the frequency range of the measurements can be extended and how rotational and lateral components can be separated reliably.