RECENT EVOLUTIONS OF METHODOLOGY IN THE ARIANE 5 LOW FREQUENCY DYNAMIC ENVIRONMENTS PREDICTIONS AND QUALIFICATION PROCESS

摘要

During the development of the Ariane 5 Evolution/Plus program, some evolutions of the launcher led to changes of methodology in the frame of the low frequency environment.For the calculation aspects, introduction of non-linear elements imposed to develop new methods of analysis. The coupled load analyses have to integrate these new methods.The flight data gathered on twenty Ariane 5 flights allows an evolution of the selection of the load-cases that are considered for these coupled load analyses: the evolution are based on direct measurement of flight or from tests performed during the development of the new version of Ariane 5.The flight measurement allows validating also the predictions. For example, in the prediction of the loads associated to the thrust oscillations of the boosters, the flight measurement led to deep analysis to correlate the models with the flight observations.In the field of qualification of the stages under the specified low frequency environment (secondary structures), the new stages and structures were submitted to qualification by test. The final process of qualification using both test and calculation was improved for the last version of the launcher.This paper deals with these recent evolutions of methodologies that were necessary to take benefice of the flight assessment or to introduce improvement of approaches necessary to take into account non linear device introduced to limit the low frequency environment of payloads.