Comparative study of experimental assessment methodologies for the dynamic characterization of elastic elements

In this paper, four distinct methods for the experimental assessment of the dynamic stiffness of elastic elements in a laboratory environment are compared. The comparison has been done experimentally in a simple mass-element-mass-isolator test rig based on the proposals presented in ISO 10846 by testing an elastomeric mat specimen. The four existing experimental approaches compared are the direct and indirect methods proposed by ISO 10846, a frequency-independent characterization method based on the transmissibility peak, and an existing methodology for in situ applications that in this work has been proposed to be used for laboratory assessments. In order to compare these methodologies, the vertical stiffness of the under-ballast mat sample has been obtained through the four methods proposed. The application of the approach also showed that the rotational degrees of freedom test rig massive elements must be considered in the characterization of elastic elements using this particular test rig configuration, especially when their rotational stiffness is low. Results show that the in situ method applied to laboratory-based setups allows for obtaining accurate results for a wide range of frequencies with a simple experimental setup.