Dynamic Identification of a Solid Rocket Motor From Firing Test Using Operational Modal Analysis

The main objective of this paper is the identification of the dynamic properties of a solid rocket motor using data recorded during a firing test, characterized by a mass variation due to the burning propeller. The dynamic identification of the motor is provided by applying Operational Modal Analysis (OMA) methodologies able to estimate the modal parameters of the structure undergoing its operative conditions. The sensitivity of the OMA approaches to deal with structures characterized by time-dependent parameters is evaluated through a numerical simulation. Moreover, a comparison between the estimates from different state-of-the-art approaches in OMA (operating in both time and frequency domain) are provided. The capabilities of the OMA methods to track the changes in the natural frequencies, damping ratios and mode shapes of the first stage of the Vega lunch vehicle will be investigated in order to asses the overall efficiency of such approaches. Copyright © 2011 by G. Coppotelli, C. Grappasonni, C. Di Trapani.