Tracking the Evolution of Modal Properties of a Solid Propellant Launcher During Static Firing Test

Abstract

During actual operating conditions, mechanical systems, such as aerospace structures, may exhibit variations in their dynamic properties. Those variations need to be carefully tracked and identified to avoid interaction with excitation sources, leading to unstable behavior or even structural failures. In this paper, signals acquired during a static firing test on a Solid Rocket Motor will be analyzed and processed using Operational modal Analysis. To analyze the evolution of natural frequencies and modal damping as the propellant is burnt, time-histories are cut into shorter segments, which are then analyzed separately. Operational PolyMAX method is applied to identify structural properties of the system and correlation techniques are implemented to track the evolution of the modes. Finally, comparison and correlation with a numerical Finite Element model is also performed to evaluate the analysis.KeywordsSolid rocketOperational modal analysisPolyMAXTime-varying system