True symmetric formulations for fluid-structure interaction in bounded domains. Finite element results
Résumé
It is proposed to establish, in a systematic way, symmetric variational formulations for the problem of transient and modal analysis of bounded coupled fluid-structure linear systems, taking into account gravity and compressibility effects. The discretization of such variational principles by fjnite element procedures leads therefore to convenient symmetric matrix systems. This question of symmetry arises from the choice of displacement type for the structure and of stress (pressure) type for the fluid. If those types of variables are simultaneously used, then modified complementary type variational procedures must be introduced in order to exhibit an adequate fluid structure coupling. This can be done by using two new variables, namely the free surface
displacement (for gravity effects) and the displacement potential of the fluid (for compressibility effects), together with the displacement field in the structure and the pressure field in the fluid. In those cases, generalized added mass operators - independent of time and circular frequency - are introduced. A link with boundary integral equation is established. Numerical fjnite element results are presented in three cases:
- incompressible hydroelastic modal analysis of a liquid propelled launch vehicle,
- elasto-acoustic modal analysis of an incompressible structure containing a compressible gas
- elastic cylinder partially fjlled with liquid under gravity efgects (comparison with experiments).
Domaines
Mécanique [physics]
Origine : Fichiers produits par l'(les) auteur(s)