Observatorio de I+D+i UPM

Memorias de investigación
Research Project:
RANDOM VIBRATION ENVIRONMENT DERIVATION BY VIBRO-ACOUSTIC SIMULATION RANDERIV - ECE-PO-B-07-480.
Year:2008
Research Areas
  • Naval engineering
Information
Abstract
It is of enormous importance to have reliable and feasible tools to help engineers in derivation of the Random Vibration Environment at equipment interface due to the launch acoustic load. Typically, two different degrees of complexity exist. In general simple discrete models of two or three degrees of freedom are available. These methods are useful in very preliminary design phases, and retain only few parameters of the system. On the other hand, numerical methods (FEM, BEM, SEA) require detailed information of the systems, which in general is not available during design phases. Besides although these mature numerical tools and the associated software capabilities allow the user to predict the acceleration levels at the equipment/panels interfaces, it has not been demonstrated yet the accuracy of the results for all possible combinations of parameters which can appear in current satellites, showing in some cases an excessive degree of uncertainty. Hence, the influence of parameters as the location of equipment in the panels, sensitivity to equipment/panels interface design, modeling of cavities, introduction of damping (loss factors and coupling loss factors) and frequency range of applicability, for example, needs to be evaluated. Some simplified analytical methodology exits, as the Joint Acceptance Analysis, Impedance/Mobility techniques and Mile¿s-like methods, which can be useful for the definition of vibration levels in the first steps of the preliminary designs. These analytical tools still need to be improved and validated in order to be able to establish the limits of their applicability. In order to obtain a reliable validation procedure, apart from updating the analytical methods with the numerical tools outputs it is needed a final validation by means of comparison with experimental results. The current ESA and NASA standard specifications for equipment random tests are based on a statistical analysis of data corresponding to several satellite projects. They are general rules with few parameters (mainly the equipment mass) in order to determine the equipment qualification test levels. Some parameters that could be important as the equipment position, interface stiffness or the acoustic scattering of the panels are not taken into account for this evaluation. The use of parametric evaluations of the numerical and analytical tools outputs and the verification by tests can improve the current existing methods of obtaining the equipment load levels. Finally, another important point of this program is that the predicted levels on satellite equipment not only must be kept in acceleration predictions, but in terms of Interface forces. Influence of boundary conditions and frequencies coupling should be numerically studied.
International
Si
Project type
Proyectos y convenios de financiación privada
Company
esa
Entity Nationality
HOLANDA-PAISES BAJOS
Entity size
Gran Empresa (>250)
Granting date
07/01/2008
Participants
  • Director: Jesus Lopez Diez (UPM)
Research Group, Departaments and Institutes related
  • Creador: Grupo de Investigación: Proyectos de Ingeniería Aeronáutica e Investigación
  • Departamento: Vehículos Aeroespaciales
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