Using transmissibility measurements for nonlinear identification

Abstract

In order to improve the predictive capability of the mathematical or numerical models of engineering structures, there is a need to capture their physical behaviour based on experimental measurements. In dynamics, this is accomplished with specific vibration tests, such as the Ground Vibration Test (GVT) used in aerospace applications. Currently, it seems that the engineering community lacks appropriate tools for the detection and quantification of dynamic nonlinearities during vibration tests. Of the nonlinear identification methods developed during the past 30 years, only a few are suitable for application on practical engineering structures. One of these has the particular advantage of requiring standard measurement techniques and sensors and is based on the analysis of Frequency Response Function (FRF) data. However, in many practical applications, structures are required to be tested by excitation of the base, so that transmissibilities are measured in place of FRFs. In this paper an existing identification method based on FRF data is shown to be applicable also when transmissibility is measured. Numerical simulations are used to demonstrate the applicability of the method.