Calcul du rayonnement acoustique de structures par décomposition sur des fonctions radiatives

Abstract
In this paper, a superposition method is presented that allows the computation of acoustic fields radiated by vibrating structures. Basically, the method of superposition applied to sound radiation consists in modelizing the vibrating structure by fictitious acoustic sources located inside it. The sources used can be punctual ones such as monopoles or dipoles ; we have developped surfaciq sources which have the advantage of a large spatial bandpass. By a numerical procedure, complex amplitudes of these sources are determined so as to satisfy the boundary conditions, usually normal velocity which is either calculated or measured. Usually authors try to minimize the difference between the known velocity and the approximated one in the least mean square sense. This method implies numerical peculiarities since it leads to ill-conditionned linear equations system. The convergence criterium in terms of velocity is very hard to achieve and it does not take into account radiation efficiency. We present a method in which we add the acoustic strength of the structure as an auxiliary condition.