Qualification to Shock Environment in VEGA Program, by full scale tests, models and similarity
- Paper number
IAC-06-C2.1.04
- Author
Dr. Marino Fragnito, ELV S.p.A, Italy
- Coauthor
Mr. Josè Luis Leofanti, ELV S.p.A., Italy
- Coauthor
Mr. Roberto Mancini, ELV S.p.A., Italy
- Coauthor
Mr. Michel Bonnet, European Space Agency/ESRIN, Italy
- Coauthor
Mr. Jean-Luc Parquet, European Space Agency/ESRIN, Italy
- Year
2006
- Abstract
Stage separation events are crucial phases for the VEGA launch vehicle mission and therefore high reliability is required to the activation and functionality of the pyrozip cutting system. Nevertheless the associated shock environment is really harsh and the generated levels may be critical especially for the electronic equipments installed in near areas. In order to characterise the Launch Vehicle shock environment, tests have been performed, first on flat samples, then at full scale on the InterStage 2/3, which links the 2nd and 3rd stage Solid Rocket Motors. The full scale test was successfully carried out in Colleferro in February 2006. The InterStage 2/3 is a stiffened cylindrical structure, about 2 m height per 2 m diameter, and includes a pyrozip able to cut a 3 mm thick flange to separate and free the launch vehicle of the expended stage. Several equipments are located in the InterStage, with the related harness, in particular the 3rd stage Thrust Vector Control components. Boundary conditions were simulated with a mock-up of the bottom part of the 3rd stage motor and nozzle in order to provide representative interfaces to the TVC Electro-Mechanical Actuators. The distancing of the two separated parts is ensured by eight springs. In the test, the upper part (3rd stage) was fixed to a hard mounted stand, while the separated lower part was accelerated down, on a recovery damping system by the action of the springs. In order to limit the development cost it was decided not to test all VEGA stage separations and in particular, since the same pyrozip system is used for 1/2 stage and 2/3 stage separation, with the same thickness to be cut, the 1/2 stage separation will be qualified by similarity making wide use of models correlated on the base of the 2/3 stage test performed. The simple shock prediction tool, based on source characterisation and equipment supports modal identification in a low-medium frequency range will be described in this paper together with the results of the correlation of the 2/3 separation test. In order to achieve modal characterisation relevant to InterStage 1/2 layout, to correctly predict the associated shock levels, a modal identification test is going to be performed in order to acquire the structure modes as far as possible in high frequencies, in particular at equipment location.
- Abstract document