Development of a Technique to Determine the Modal Characteristics of Structures Using Response Data

This article describes a technique which has been developed recently to analyse response data measured from structures in order to be able to determine the modal characteristics. Previously, this technique, which was developed from so-called Dat and Meurzec approach for analysing response signals, has been successfully applied to data measured from aircraft during flight tests, the modal characteristics of the structure being required for the prediction of the onset of flutter. To further explore the potential applications of this apparently robust modal curvefitting technique, a case study has been performed using data measured from a car undergoing tests on a 4-poster road simulation rig. Different physical factors such as the friction in the shock absorbers make the vehicle suspensions significantly non-linear. By curvefitting to data measured during tests designed to simulate different road surfaces, the objective was to monitor the dynamic characteristics of the vehicle and determine the dependence on the level of excitation.