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Rotating Structure Modeling and Damping Measurements
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
2011 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

The structural damping is of importance to suppress the vibration amplitude of compressor blades rotating at high angular velocity under a high cycle impact. To avoid the appearance of the high cycle fatigue (HCF), damping materials may be applied to the compressor blades. To quantify the effect while using damping materials, a numerical tool needs to be developed for the damping prediction of a dynamic rotating blade. This thesis is divided into two parts: Paper A develops a dynamic model of a rotating blade and Paper B a damping structure model including measurements.

In Paper A, a dynamic rotating blade model is developed by using a plate model at an arbitrary stagger angle. Hamilton’s principle is applied to derive a system of equations of motion and the corresponding boundary conditions. Numerical simulation is implemented to perform eigenfrequency analysis by the Extended Galerkin method. In addition, parametric analysis is performed with respect to rotation speed and stagger angle, respectively. Results show a good agreement with those of the finite element method. Finally, forced response analysis is determined for two cases; a point force and a distribution force, using a proportional damping model.

In Paper B, unconstrained and constrained damping techniques are applied to increase the structural damping of the blades, including measurement and modeling results. Two specimens, titanium and stainless steel, are treated by aluminum oxide and epoxy coating material. Measurement results show that both treatments give damping increase, where aluminum oxide is more effective for damping improvement than the corresponding epoxy treatment. The unconstrained damping layer model is used to predict the total material damping of the combined structure as well as the material damping of coating layer. Furthermore, the constrained-layer model is used to optimize the damping configuration. Two compressor blades in titanium and stainless steel are tested in air and vacuum. One reason is being that the radiation loss factor increases the total damping comparing with that under vacuum condition. The calculation of radiation loss factor is performed to match the measurement data. Finally, increased material damping decreases peak stress and therefore increases the life time of the compressor blades.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology , 2011. , 40 p.
Series
Trita-AVE, ISSN 1651-7660 ; 2011:19
National Category
Fluid Mechanics and Acoustics Vehicle Engineering
Research subject
Järnvägsgruppen - Ljud och vibrationer
Identifiers
URN: urn:nbn:se:kth:diva-31161ISBN: 978-91-7415-916-5OAI: oai:DiVA.org:kth-31161DiVA: diva2:402973
Presentation
2011-03-30, MWL 74, Teknikringen 8, KTH, Stockholm, 10:00 (English)
Opponent
Supervisors
Funder
TrenOp, Transport Research Environment with Novel Perspectives
Note

QC 20110311

Available from: 2011-03-11 Created: 2011-03-10 Last updated: 2013-02-15Bibliographically approved
List of papers
1. A dynamic rotating blade model at an arbitrary stagger angle based on classical plate theory and the Hamilton's principle
Open this publication in new window or tab >>A dynamic rotating blade model at an arbitrary stagger angle based on classical plate theory and the Hamilton's principle
2013 (English)In: Journal of Sound and Vibration, ISSN 0022-460X, E-ISSN 1095-8568, Vol. 332, no 5, 1355-1371 p.Article in journal (Refereed) Published
Abstract [en]

A dynamic model based on classical plate theory is presented to investigate the vibration behavior of a rotating blade at an arbitrary stagger angle and rotation speed. The Hamilton's principle is applied to derive the equations of motion, which are discretised by a novel implementation of the fast and efficient collocation method for rotating structures and by the traditional Extended Galerkin method. The results obtained with these methods are compared and validated with results found in the literature and from commercial finite element software. The proposed collocation method leads to a significantly lower computation time than the Extended Galerkin method for the same accuracy. The results show a good agreement with those of the finite element method. Finally, the forced response analysis is determined for two cases; a point force and a distribution force, using a proportional damping model.

Keyword
Classical plate theory, Collocation method, Computation time, Damping model, Finite element software, Forced response analysis, Hamilton's principle, Point force, Rotating blades, Rotating structures, Rotation speed, Stagger angle, Vibration behavior
National Category
Applied Mechanics
Identifiers
urn:nbn:se:kth:diva-31158 (URN)10.1016/j.jsv.2012.10.030 (DOI)000313919800013 ()2-s2.0-84871220052 (ScopusID)
Funder
Swedish Energy Agency
Note

QC 20130215. Updated from accepted to published.

Ingår i avhandling, något modifierad

Available from: 2011-03-10 Created: 2011-03-10 Last updated: 2013-08-07Bibliographically approved
2. Coating methods to increase material damping of compressor blades: measurements and modeling
Open this publication in new window or tab >>Coating methods to increase material damping of compressor blades: measurements and modeling
2010 (English)In: Proceedings of ASME Turbo Expo 2010: Vol 6, Pts A and B, ASME Press, 2010, 1157-1165 p.Conference paper (Refereed)
Abstract [en]

Methods are developed to improve damping of compressor blades, where unconstrained and constrained damping techniques are applied to the blades to increase material damping, displaying both measurement and modeling results. Two specimens, titanium and stainless steel, are treated by aluminum oxide and epoxy coating material. Measurements of material damping of simple beam specimens without and with treatments are carried out and results show that both treatments give damping increase, where aluminum treatment is more effective for damping improvement than the corresponding epoxy treatment. The unconstrained damping layer model is used to predict the total material damping of the combined structure as well as the material damping of coating layer. Comparisons with measured results are made. The constrained-layer model is also used to optimize the damping configuration and parametric analyses are performed. Two compressor blades in titanium and stainless steel are tested in air and vacuum conditions to measure material damping and results show that difference between air and vacuum situations exists. One reason is being that the radiation loss factor produced in air condition increases damping comparing with the damping in vacuum condition. The calculation of the radiation loss factor is performed to match the measurement data and results demonstrate that the radiation loss factor is one factor and air friction is another strong factor in this case. Finally, increasing material damping gives a contribution to decrease peak stress values and therefore increase the life time of compressor blades.

Place, publisher, year, edition, pages
ASME Press, 2010
Keyword
Air conditions, Air friction, Aluminum oxides, Coating layer, Coating methods, Combined structure, Compressor blades, Damping layers, Epoxy coatings, In-vacuum, Life-times, Material damping, Measured results, Measurement data, Modeling results, One-factor, Parametric analysis, Peak stress, Radiation loss, Vacuum condition
National Category
Applied Mechanics
Identifiers
urn:nbn:se:kth:diva-31159 (URN)10.1115/GT2010-23790 (DOI)000290927800117 ()2-s2.0-82055184855 (ScopusID)978-079184401-4 (ISBN)
Conference
ASME Turbo Expo 2010: Power for Land, Sea, and Air, GT 2010; Glasgow; United Kingdom; 14 June 2010 through 18 June 2010
Note

QC 20110311

Available from: 2011-03-10 Created: 2011-03-10 Last updated: 2014-09-03Bibliographically approved

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