Analysis of dynamic characteristics and their sensitivities for anisotropy mistuned bladed disks with friction contact interfaces

Koscso, Adam (2022) Analysis of dynamic characteristics and their sensitivities for anisotropy mistuned bladed disks with friction contact interfaces. Doctoral thesis (PhD), University of Sussex.

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In the modern jet engines single-crystal materials are used for turbine stages to withstand the high pressures, temperatures and to have sufficient creep resistance. Single crystal materials are inherently anisotropic, and their properties are dependent on the crystal orientation. The current technology of blade manufacturing by controlled solidification of the blades produces significant scatter in the crystal orientation. The mistuning introduced in bladed disks by blade material orientation scatter and by inevitable differences between blade-disk, shroud and dampers’ contact interfaces, can lead to the increase of vibratory amplitudes and stress localization. This work aims to quantify the effect blade-to-blade anisotropy orientation on the vibratory characteristics of bladed disks.

In the thesis the effects of the anisotropy mistuning on the modal properties and forced response have been studied using high-fidelity FE models together with detailed modelling of nonlinear interaction at friction contact interfaces at blade-disk root joints, blade-shroud and underplatform damper contacts.

For the analysis of the sensitivity of natural frequencies and mode shapes with respect to the material anisotropy orientation in blades, efficient methods have been developed and implemented.

The sensitivity calculations for the modal properties, linear and nonlinear forced response have been validated by finite difference method. The calculated nonlinear forced response functions have been validated against measurement data from rotating test rigs. The efficient modeling strategies were explored and studied to address the common issues that occur during the nonlinear forced response analysis of large mistuned bladed disk models.

The effects of the material anisotropy mistuning in bladed disks on natural frequencies, mode shapes and on linear and nonlinear forced response amplitudes for several modes have been studied. For the nonlinear forced response, the effect of anisotropy mistuning has been studied for varying excitation levels and damping levels. The characteristics of the sensitivities of modal properties and nonlinear forced response amplitudes to the anisotropy angles have been studied for several industrial mistuned bladed disks.

Item Type: Thesis (Doctoral)
Schools and Departments: School of Engineering and Informatics > Engineering and Design
Subjects: T Technology > TL Motor vehicles. Aeronautics. Astronautics > TL0500 Aeronautics. Aeronautical engineering
Depositing User: Library Cataloguing
Date Deposited: 07 Apr 2022 09:10
Last Modified: 13 Apr 2022 19:55

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