Modal characterisation of an Ariane 5 booster using vibration response data of a firing test

Abstract

A firing test of a solid propellant booster, being under development for the European ARIANE 5 launcher, was used to acquire vibration response data suitable to characterise the booster’s lowest bending modes. The objective of this activity was to qualify and to validate the mathematical models of the booster and to complete the studies of the flight control systems. This paper gives an overview of the analytical preparation and selection of suitable nozzle activation sequences that should provide sufficient excitation of the lateral booster modes, and it reports on the prediction of the booster responses needed to avoid the violation of security requirements of the firing test. Some specific details of the test installations, the processing of the response data and the procedures utilised in the modal characterisation task are presented. Finally, the test results are correlated with a refined and an updated mathematical model of the booster.