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Numerical analysis of multiple friction contacts in bladed disks
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.ORCID iD: 0000-0003-4237-2630
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL. Eindhoven University of Technology.ORCID iD: 0000-0002-3609-3005
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.ORCID iD: 0000-0001-5760-3919
(English)In: International Journal of Mechanical Sciences, ISSN 0020-7403, E-ISSN 1879-2162Article in journal (Other academic) Submitted
Abstract [en]

The damping potential of multiple friction contacts in a bladed disk, tip shroud and strip damper is investigated, showing that friction damping effectiveness can be potentially increased by using multiple friction contact interfaces. Friction damping depends on many parameters such as rotational speed, engine excitation order and mode family and therefore it is not possible to damp all the critical resonances using a single friction contact interface. For example, a strip damper is more effective for the low nodal diameters, where blade/disk coupling is strong. The equations of motion of the bladed disk with multiple friction contacts are derived in the frequency domain for a cyclic structure with rotating excitations and a highly accurate method is used to generate the frequency response function (FRF) matrix. Furthermore, a finite element contact analysis is performed to compute the normal contact load and the contact area of the shroud interface at operating rotational speed. The multiharmonic balance method is employed in combination with the alternate frequency time domain method to find the approximate steady state periodic solution. A low-pressure turbine bladed disk is considered and the effect of the engine excitation level, strip mass, thickness and the accuracy of FRF matrix on the nonlinear response curve are investigated in detail.

Keyword [en]
Friction damping, Shroud contact, Strip damper, Cyclic symmetry, Alternate frequency time domain method, Multiharmonic balance method.
National Category
Applied Mechanics
Research subject
Engineering Mechanics
Identifiers
URN: urn:nbn:se:kth:diva-202994OAI: oai:DiVA.org:kth-202994DiVA: diva2:1080749
Projects
TurboPower
Funder
Swedish Energy Agency, 26159
Note

QC 20170313

Available from: 2017-03-10 Created: 2017-03-10 Last updated: 2017-03-13Bibliographically approved
In thesis
1. On efficient and adaptive modelling of friction damping in bladed disks
Open this publication in new window or tab >>On efficient and adaptive modelling of friction damping in bladed disks
2017 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This work focuses on efficient modelling and adaptive control of friction damping in bladed disks. To efficiently simulate the friction contact, a full-3D time-discrete contact model is reformulated and an analytical expression for the Jacobian matrix is derived that reduces the computation time drastically with respect to the classical finite difference method. The developed numerical solver is applied on bladed disks with shroud contact and the advantage of full-3D contact model compared to a quasi-3D contact model is presented. The developed numerical solver is also applied on bladed disks with strip damper and multiple friction contacts and obtained results are discussed. Furthermore, presence of higher harmonics in the nonlinear contact forces is analyzed and their effect on the excitation of the different nodal diameters of the bladed disk are systematically presented. The main parameters that influence the effectiveness of friction damping in bladed disks are engine excitation order,  contact stiffnesses,  friction coefficient, relative motion at the friction interface and the normal contact load. Due to variation in these parameters during operation, the obtained friction damping in practice may differ from the optimum value. Therefore, to control the normal load adaptively that will lead to an optimum damping in the system despite these variations, use of magnetostrictive actuator is proposed. The magnetostrictive material that develops an internal strain under the influence of an external magnetic field is employed to increase and decrease the normal contact load. A linearized model of the magnetostrictive actuator is used to characterize the magnetoelastic behavior of the actuator.  A nonlinear static contact analysis of the bladed disk reveals that a change of normal load more than 700 N can be achieved using a reasonable size of the actuator. This will give a very good control on friction damping once applied in practice.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2017. 70 p.
Series
TRITA-AVE, ISSN 1651-7660 ; 2017:10
Keyword
High cycle fatigue, Friction contact, Jacobian matrix, Shroud contact, Strip damper, Multiharmonic balance method, Contact stiffness, Cyclic symmetry, Nodal diameter, Magnetostrictive actuator, Magnetic field
National Category
Applied Mechanics Energy Engineering
Research subject
Engineering Mechanics
Identifiers
urn:nbn:se:kth:diva-202978 (URN)978-91-7729-292-0 (ISBN)
Public defence
2017-04-12, F3, Lindstedtsvägen 26, Stockholm, 10:00 (English)
Opponent
Supervisors
Projects
TurboPower
Funder
Swedish Energy Agency, 26159
Note

QC 20170310

Available from: 2017-03-13 Created: 2017-03-10 Last updated: 2017-03-13Bibliographically approved

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