Development of experimental test setups for bladed disks and non-linear vibration

Download

index.pdf

Date

2019

Author

Öney, Eren

Metadata

Show full item record

This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Item Usage Stats

133
views

69
downloads

High-cycle fatigue is one of the most frequent reason of failure for turbomachines and in early design process, so it is crucial to predict the vibration levels. Various finite element modelling techniques for bladed-disk systems appear in the literature, including both reducing large size FEM and describing the frictional contact interface. However, not only having a large size FEM but also including the nonlinear friction to models makes the task very struggling and time consuming. In order to enhance the working life, resonances should be avoided but, it is not easy to avoid all critical resonances on turbomachinery due to the broad spectrum of aerodynamic excitation. Thus, decreasing the vibration amplitudes become necessary. The vibration amplitudes of the system can be reduced by the initial gap and friction between the shroud contact interface which is a nonlinear contact phenomenon. Therefore, calculating the dynamic properties of system is a major problem. This study is conducted in order to understand the nonlinear frictional contact behavior and gap nonlinearity which affects the damping characteristics of the shrouded blades. To do so, two experimental test setups are developed. First one consists of a shrouded blade to measure dynamic responses of stationary shrouded blade with gap nonlinearity. The effects of different shroud contact angle, shroud positions along radial direction, initial gap and different excitation forces are investigated on the first bending mode of the blade. In the second test, an under platform damper setup is prepared. The effect of friction and normal preload at the contact surface is investigated. During both tests, a modal shaker for excitation and a data acquisition system with accelerometers are used for measurement.

Subject Keywords

Blades., Gap Nonlinearity, Friction Nonlinearity, Bladed Disk, Experimental Nonlinear Vibration, Under Platform Damper.

URI

http://etd.lib.metu.edu.tr/upload/12624806/index.pdf
https://hdl.handle.net/11511/45402

Collections

Graduate School of Natural and Applied Sciences, Thesis

Suggestions

OpenMETU
Core

Design of an Experimental Setup for Periodic Forced Response Analysis of Shrouded Blades with Frictional Contacts Öney, Eren; Ciğeroğlu, Ender (null; 2019-11-02) High-cycle fatigue is one of the most frequent reasons of failure for turbomachinery and in early design process it is crucial to predict the vibration levels. Friction dampers or frictional contacts are commonly used in the design of gas turbine engines in order to decrease vibration levels and increase high-cycle fatigue lives of blades. However, due to the nonlinear behavior, dry friction complicates analysis of these systems. In this study, in order to understand the nonlinear frictional contact behavio...
Implementation of Dirlik’s damage model for the vibration fatigue analysis Demirel, Gürzap İ.; Kayran, Altan (2019) Mechanical fatigue is an important phenomenon when the structures are exposed to dynamic, fluctuating loadings. Especially aerospace structures are commonly exposed to random vibration loadings. In this paper, random vibration fatigue is studied both numerically and experimentally. For this purpose, a rectangular cross-section notched beam is designed in order to conduct the vibration fatigue analysis in the frequency domain by the Dirlik's damage model. Aluminum and steel notched beams are prepared in orde...
Determining the endurance limit of AISI 4340 steels in terms of different statistical approaches Caliskan, Salim; Gürbüz, Rıza (2021-10-01) In engineering applications, fatigue phenomenon is a key issue and needs to be analyzed in the beginning of design phase in case of any component exposed to alternating loading on operation otherwise catastrophic fatigue failure may cause. Component can be designed with safe life, fail-safe, and damage tolerant approach based on whether redundant load path and damage sensitive. Before starting analyzing the structure, material allowable data needs to be presented in a reliable way to predict fatigue life of...
Investigation of the effect of structural damping on wind turbine wind-induced fatigue loads Kocan, Cagri; Özgen, Gökhan Osman (2022-09-01) This paper presents a quantitative investigation of the effect of structural damping ratios of the tower and blade vibration modes of wind turbines on wind-induced fatigue loads at critical blade and tower sections. Fatigue loads are used as a relative measure of fatigue life in wind turbine design applications. By increasing the structural damping ratio of each one of the critical structural modes which highly contribute to the overall vibration response, short-term and lifetime fatigue loads at critical t...
Development of a passive vibration isolation analysis and optimization software for mechanical systems Baytemir, Ozan Yavuz; Ciğeroğlu, Ender; Özgen, Gökhan Osman; Department of Mechanical Engineering (2014) In the design stage of a mechanical structure, the effects of vibration are taken into consideration as important design criteria. In order to eliminate the adverse effects of vibration sources, a direct intervention to the vibration source, structural reinforcement or the use of vibration isolators are encountered as the most popular vibration control methods. Among all, being compact, low cost, reliable and maintenance free, elastomeric passive vibration isolators with linear properties are examined withi...

Citation Formats

E. Öney, “Development of experimental test setups for bladed disks and non-linear vibration,” Thesis (M.S.) -- Graduate School of Natural and Applied Sciences. Mechanical Engineering., Middle East Technical University, 2019.