A Parameter Optimization for Mode Shapes Estimation Using Kriging Interpolation

2014 ◽  
pp. 287-293
Author(s):  
Minwoo Chang ◽  
Shamim N. Pakzad
Keyword(s):  
Parameter Optimization ◽  
Mode Shapes ◽  
Kriging Interpolation

Numerical Investigation of the Effect of Operating Point on the Aerodynamic Excitation in a Radial Turbine Stage

2020 ◽  
Author(s):  
Nikola Kovachev ◽  
Damian M. Vogt
Keyword(s):  
Rotational Speed ◽  
Adaptive Sampling ◽  
Expansion Ratio ◽  
Forced Response ◽  
Operating Point ◽  
Mode Shapes ◽  
Kriging Interpolation ◽  
Computational Time ◽  
Turbine Stage ◽  
Radial Turbine

Abstract The effect of operating point on the aerodynamic excitation that causes forced response vibrations in turbomachinery blading is studied numerically. For this purpose, a novel method for rapid assessment of large operating point variations on the mode excitability is introduced. This method includes a surrogate modeling approach based on Kriging interpolation in combination with an adaptive sampling technique. The data for the model is predicted by means of unsteady Computational Fluid Dynamics (CFD) simulations with the Nonlinear Harmonic (NLH) method in the frequency domain. The concept of an excitation map describing the excitation as a function of rotational speed and expansion ratio is introduced. Excitation maps for the blade passing frequency are obtained for ten mode shapes and two total inlet temperatures in a radial turbine stage. The analysis of the excitation maps has shown that the aerodynamic excitation can be reduced similarly to a performance map and used for different inlet conditions. The effect of the rotational speed appears largely mode dependent and without a clear trend. On the other hand, an increase of the expansion ratio leads to higher excitation for all mode shapes. A study of the harmonic pressure field causing the aerodynamic excitation showed that these dependencies are driven by changes in the velocity triangle and pressure at the rotor inlet. Considering the relatively short computational time to obtain multiple excitation maps, the presented approach is considered suitable to be used for optimizing turbine designs with respect to minimizing the aerodynamic excitation.

Tire Vibrations

1977 ◽  
Vol 5 (4) ◽  
pp. 202-225 ◽  
Author(s):  
G. R. Potts ◽  
C. A. Bell ◽  
L. T. Charek ◽  
T. K. Roy
Keyword(s):  
Natural Frequencies ◽  
Standing Waves ◽  
Resonant Mode ◽  
Mode Shapes ◽  
Resonant Vibrations ◽  
Resonant Frequencies ◽  
Radial Tire ◽  
Analysis Techniques ◽  
Thin Ring ◽  
Good Agreement

Abstract Natural frequencies and vibrating motions are determined in terms of the material and geometric properties of a radial tire modeled as a thin ring on an elastic foundation. Experimental checks of resonant frequencies show good agreement. Forced vibration solutions obtained are shown to consist of a superposition of resonant vibrations, each rotating around the tire at a rate depending on the mode number and the tire rotational speed. Theoretical rolling speeds that are upper bounds at which standing waves occur are determined and checked experimentally. Digital Fourier transform, transfer function, and modal analysis techniques used to determine the resonant mode shapes of a radial tire reveal that antiresonances are the primary transmitters of vibration to the tire axle.

Effect of Bass Bar Tension on Modal Parameters of a Violin's Top Plate

2015 ◽  
Vol 39 (1) ◽  
pp. 145-149 ◽  
Author(s):  
Ewa B. Skrodzka ◽  
Bogumił B.J. Linde ◽  
Antoni Krupa
Keyword(s):  
Modal Analysis ◽  
Experimental Modal Analysis ◽  
Mode Shapes ◽  
Modal Parameters ◽  
Normal Value ◽  
Modal Damping

Abstract Experimental modal analysis of a violin with three different tensions of a bass bar has been performed. The bass bar tension is the only intentionally introduced modification of the instrument. The aim of the study was to find differences and similarities between top plate modal parameters determined by a bass bar perfectly fitting the shape of the top plate, the bass bar with a tension usually applied by luthiers (normal), and the tension higher than the normal value. In the modal analysis four signature modes are taken into account. Bass bar tension does not change the sequence of mode shapes. Changes in modal damping are insignificant. An increase in bass bar tension causes an increase in modal frequencies A0 and B(1+) and does not change the frequencies of modes CBR and B(1-).

Оптимизация параметров машины для уборки лука-репки с укладкой в валок

2018 ◽  
Author(s):  
I.I. Irkov ◽  
V.G. Selivanov ◽  
N.V. Romanovskiy
Keyword(s):  
Soil Moisture ◽  
Operating Procedure ◽  
Parameter Optimization ◽  
Stable Operating

Изложены результаты оптимизации параметров машины для уборки лука-репки с укладкой в валок. Установлено, что покрытие фторопластом подкапывающих ножей, выполненных по криволинейной поверхности, и опорного катка обеспечивает стабильный технологический процесс машины при влажности почвы до 26%.The results of parameter optimization for onion harvesting machine with swath emplacement are stated. Teflon (fluoroplastic) coating of curvilinear digging shares and track roller provides stable operating procedure up to 26% soil moisture.

Comparative Analysis on Parameter Optimization for ARPT

2018 ◽  
Vol 6 (12) ◽  
pp. 349-354
Author(s):  
K. Devika Rani Dhivya ◽  
V.S. Meenakshi
Keyword(s):  
Comparative Analysis ◽  
Parameter Optimization

Machining Parameter Optimization of Bidirectional CFRP Composite Pipe by Genetic Algorithm

2014 ◽  
Vol 56 (9) ◽  
pp. 728-736 ◽  
Author(s):  
Krishnasamy Vijaykumar ◽  
Kavan Panneerselvam ◽  
Abdullah Naveen Sait
Keyword(s):  
Genetic Algorithm ◽  
Parameter Optimization ◽  
Composite Pipe ◽  
Cfrp Composite ◽  
Machining Parameter
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