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res:
bibo_abstract:
- In turbomachinery, friction contacts are widely used to reduce dynamic stresses
in turbine blades in order to avoid expensive damages. As a result of energy dissipation
in the friction contacts the blade vibration amplitudes are reduced. In case of
so-called friction dampers, which are pressed on the platforms of the blades by
centrifugal forces, the damping effect can be optimized by varying the damper
mass. This optimization can be done by means of a simulation model applying the
so-called component mode synthesis and the Harmonic Balance Method to reduce computation
time. It is based on the modal description of each substructure. In a real turbine
or compressor blading great differences in the magnitude of the individual blade
amplitudes occur caused by unavoidable mistuning of all system parameters like
contact parameters and natural frequencies of the blades. It may happen that most
of the blades experience only small stresses whereas a few blades experience critical
stresses. Therefore, it is necessary to consider mistuning for all system parameters
to simulate the forced response of bladed disk assemblies with friction contacts.
For a mistuned bladed disk the complete system has to be modeled to calculate
the dynamic response. In practice, usually the standard deviations instead of
the distributions of the system parameters are known. Therefore, Monte-Carlo simulations
are necessary to calculate the forced response of the blades for given mean values
and standard deviations of the system parameters. To reduce the computational
time, an approximate method has been developed and extended for small and moderate
standard deviations of the system parameters to calculate the distribution and
the envelopes of the frequency response functions for statistically varying system
parameters, in the following called statistical mistuning. The approximate method
is based on a sensitivity analysis and the assumption of a Weibull distribution
of the vibration amplitudes of the blades. Both, the approximate method and the
assumption of a Weibull distribution of the vibration amplitudes are validated
by Monte-Carlo simulations. By these investigations the influence of different
arrangements of the system parameters for given mean values and standard deviations
of the vibration amplitudes of the blades can be determined, too. For the present
investigations only a small influence of the arrangement of blades with respect
to their natural frequencies has been observed. On the other hand, an intentional
mistuning of the damper masses and the natural frequencies of the blades in a
systematic way, in the following called systematic mistuning, can be investigated
to reduce the amplitudes of the system. The simulation results of a systematic
mistuning has been validated by a test rig with a rotating bladed disk assembly
with friction dampers. The investigations show a good agreement between the simulations
and the measurements but only a slight decrease of the maximum amplitudes in case
of a systematic mistuning. Copyright {\copyright} 2004 by ASME@eng
bibo_authorlist:
- foaf_Person:
foaf_givenName: Florian
foaf_name: Götting, Florian
foaf_surname: Götting
- foaf_Person:
foaf_givenName: Walter
foaf_name: Sextro, Walter
foaf_surname: Sextro
foaf_workInfoHomepage: http://www.librecat.org/personId=21220
- foaf_Person:
foaf_givenName: Lars
foaf_name: Panning, Lars
foaf_surname: Panning
- foaf_Person:
foaf_givenName: Karl
foaf_name: Popp, Karl
foaf_surname: Popp
bibo_issue: GT2004-53310
bibo_volume: 6
dct_date: 2004^xs_gYear
dct_language: eng
dct_subject:
- Friction
- Disks
dct_title: Systematic mistuning of bladed disk assemblies with friction contacts@
...