This report presents the bending modes study conducted on a heavy launcher. The controller of the launcher takes as inputs the attitude and attitude rate measurements given by the Inertial Measurement Unit (IMU). Since the bending modes generate measurement errors at the IMU location, the study of deformations due to these bending modes is critical to assess the stability of the launcher during the atmospheric flight phase. The goal of this master thesis project is to detect and then select the most excitable bending modes among the large number of modes provided by a detailed structural analysis of the launcher. Only these relevant modes will be later used to generate reduced dynamical models of the launcher in order to efficiently design an appropriate controller. Indeed, considering all the bending modes will dramatically increase the calculation time and will not significantly improve the representativeness of the model at the control law frequency range of interest. To reach this objective, an extended excitability (the maximum of the module of the transfer function between the effective deflection and the considered mode generalized coordinate transported at the IMU location) is defined and computed for each mode. A criterion has been implemented to choose only the relevant modes. The sensitivity study conducted during this master thesis project has shown that with around 20 modes over 200, one can reproduce the dynamic behavior of the complete system. ; Denna rapport presenterar studien för böjningslägen som utförts på en bärraket. Eftersom böjningslägen genererar mätfel vid IMU-platsen är studien av deformationer på grund av dessa böjningslägen avgörande för att bedöma stabiliteten under den atmosfäriska flygfasen. Målet med detta examensarbete är att upptäcka och sedan välja de mest spännande böjningslägena bland det stora antalet lägen som tillhandahålls av en detaljerad strukturanalys av bärraketen. Endast dessa relevanta lägen kommer senare att användas för att generera reducerade dynamiska modeller ...
Bending modes analysis in atmospheric flight for heavy launcher
2019-01-01
Theses
Electronic Resource
English
DDC: | 629 |
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