Reflector vibroacoustic response to launch acoustic excitation

In the context of an ARTES 5 ESTEC/ESA programme, EADS CASA Espacio (ECE) has performed a development able to meet and excel the demanding requirements for the telecommunications reflector antenna. The 2.4 m diameter deployable reflector manufactured and tested in the frame of the program is used as reference data for the paper. The crucial requirement for the large size deployable reflectors is often the survival of the acoustic vibration test, and can be defined as the design driver load case. In addition, the telecommunication market demands lighter structures as an objective to reduce costs. For an efficient optimisation of the product it is very important to have powerful structural analysis tools in order to obtain knowledge of the structural needs and to refine existing methods for the prediction of structural loads experienced by an antenna reflector during acoustic testing. This paper describes the modelling, analysis and correlation of the dynamic response of these large composite spacecraft antenna structures subjected to a diffuse acoustic field excitation. Due to the dynamic behaviour of the deployable reflectors and based on the heritage of the ECE products, the analysis is centred in the low frequency regime up to 300 Hz; therefore FEM-BEM coupled analysis has been used as adequate approach for the acoustic response simulation. As verification exercise the correlation of the acoustic vibration test of the 2.4m diameter deployable reflector is presented. In the frame of this program a new analysis methodology has been used and verified, as design and test control guide. The vibro-acoustic analysis tool VA-ONE has been calibrated as a future application for the ECE commercial reflectors. One of the main goals intended with this new analysis methodology has been to provide an efficient dimensioning of margin and good support during the reflector test. It allows obtaining the frequency response data of the reflector´s behaviour not only in terms of accel- - eration but also in terms of stress and force response. In summary, the extra data drives to the more accurate optimization of the structure by covering local strength reinforcements and global lightening.