On the use of mesh morphing techniques in reduced order models for the structural dynamics of geometrically mistuned blisks

Abstract

A technique is proposed to overcome computational issues caused by the use of multiple meshes in reduced order models (ROMs) for the structural dynamics of mistuned blisks. Due to the need for repairs (blends) or geometric changes during design iterations, models often require the use of distinct meshes for the same component. Most ROMs for such cases start from pristine modal information, which must be obtained for every mesh involved. Due to the nature of normal modes in cyclic structures, a first challenge arises with respect to their correct clocking, or alignment. Modes have arbitrary clocking for cyclic symmetric systems, and hence modes are potentially different for different meshes. In addition to this, imperfect clocking and cyclic interface compatibility can strongly affect the accuracy of the predicted response. This paper presents a method to preserve the accuracy of ROMs and at the same time reduce the computational overhead associated with the presence of multiple morphed meshes. Numerical issues associated with the presence of multiple meshes and sets of modes are investigated.