Reduced order modeling and vibration analysis of mistuned bladed disk assemblies with shrouds

This paper presents important improvements and extensions to a computationa lly efficient reduced order modeling technique for the vibration analysis o f mistuned bladed disks. In particular, this work shows how the existing mo deling technique is readily extended to turbomachinery rotors with shrouded blades. The modeling technique employs a component mode synthesis approach to systematically generate a reduced order model (ROM) using component mod es calculated from a finite element model (FEM) of the rotor. Based on the total number of degrees of freedom, the ROM is typically two or three order s of magnitude smaller than the FEM. This makes it feasible to predict the forced response statistics of mistuned bladed disks using Monte Carlo simul ations. In this work, particular attention is devoted to the introduction o f mistuning into the ROM of a shrouded assembly. Mistuning is modeled by pr ojecting the mistimed natural frequencies of a single, cantilever blade wit h free shrouds onto the harmonic modes of the shrouded blade assembly. Thus , the necessary mistuning information may be measured by testing individual blades.