Modèle probabiliste des incertitudes en dynamique des structures pour le désaccordage des roues aubagées

Abstract

The mistuning of blades is frequently the cause of spatial localizations for the dynamic forced response in turbomachinery industry. The random character of mistuning requires the construction of probabilistic models of random uncertainties. A usual parametric probabilistic description considers the mistuning through the Young modulus of each blade. This model consists in mistuning blade eigenfrequencies, assuming the blade modal shapes unchanged. Recently a new approach known as a non-parametric model of random uncertainties has been introduced for modelling random uncertainties in elastodynamics. This paper proposes the construction of a non-parametric model which is coherent with all the uncertainties which characterize mistuning. As mistuning is a phenomenon which is independent from one blade to another one, the structure is considered as an assemblage of substructures. The mean reduced matrix model required by the non-parametric approach is thus constructed by dynamic substructuring. A comparative approach is also needed to study the influence of the non-parametric approach for a usual parametric model adapted to mistuning. A numerical example is presented.