Forced Response Analysis of High-Mode Vibrations for Mistuned Bladed Disks With Effective Reduced-Order Models

Abstract

This paper is focused on the analysis of effects of mistuning on the forced response of gas turbine engine bladed disks vibrating in the frequency ranges corresponding to higher modes. For high modes considered here, the blade aerofoils are deformed during vibrations and the blade mode shapes differ significantly from beam mode shapes. A model reduction technique is developed for the computationally efficient and accurate analysis of forced response for bladed disks vibrating in high-frequency ranges. The high-fidelity finite element (FE) model of a tuned bladed disk sector is used to provide primary information about dynamic properties of a bladed disk, and the blade mistuning is modeled by specially defined mistuning matrices. The forced response displacement and stress amplitude levels are studied. The effects of different types of mistuning are examined, and the existence of high amplifications of mistuned forced response levels is shown for high-mode vibrations: in some cases, the resonance peak response of a tuned structure can be lower than out-of-resonance amplitudes of its mistuned counterpart.

Mistuning sensitivity and optimization for bladed disks using high-fidelity models

“…Because of this, we use in this paper the effective reduced-order method for determination of mistuned bladed disk modal properties which is proposed in Ref. [21]. The forced response of a mistuned structure can be effectively calculated by using the concept of modal excitation forces:…”

“…see Refs. [21] and [22]); (ii) blade material anisotropy orientation mistuning for bladed made of monocrystalline material (see. Ref.…”

“…The distribution of the lumped masses are kept the same for all mistuned blades (as it is done in Refs. [21] and [22]) and in order to obtain j -th blade with the required mistuning the reference mistuning matrix is multiplied by a coefficient…”

“…It should be noted that owing to the fact that matrix S δM is diagonal with sparsely-spaced non-zero entries and the matrix products T S j δ Φ M are calculated once and then used in all expressions in Eqs. (21) and (22) the forced response sensitivities can be calculated sufficiently fast.…”

Nodal diameter vibration identification of coated blisk under traveling wave excitation

“…Much of the theoretical work about vibration characteristics have been done. For example, Duan et al 3 created a high-fidelity finite element (FE) model of bladed disk and analyzed the forced response under the higher engine order excitation. Bladh et al 4 studied Craig-Bampton (C-B) method of CMS for mistuned blisk and considered engine order excitation as the external excitation force vector.…”