Prediction of Turbomachinery Aeroelastic Behavior From a Set of Representative Modes

2011 ◽  
Author(s):  
Mari´a A. Mayorca ◽  
Damian M. Vogt ◽  
Hans Ma˚rtensson ◽  
Torsten H. Fransson
Keyword(s):  
Wide Frequency Range ◽  
Least Square ◽  
Mode Shapes ◽  
Frequency Range ◽  
Reduced Order ◽  
Transonic Compressor ◽  
Unsteady Aerodynamic ◽  
Shape Perturbation ◽  
Selection Of

A method is proposed for the determination of the aeroelastic behavior of a system responding to mode-shapes different to the tuned in-vacuo ones, due to mistuning, mode family interaction or any other source of mode-shape perturbation. The method is based on the generation of a data base of unsteady aerodynamic forces arising from the motion of arbitrary modes and uses Least Square approximations for the prediction of any responding mode. The use of a reduced order technique allows for mistuning analyses and is also applied for the selection of a limited number of arbitrary modes. The application on a transonic compressor blade shows that the method captures well the aeroelastic properties in a wide frequency range. A discussion of the influence of the mode-shapes and frequency on the final stability response is also provided.

Prediction of Turbomachinery Aeroelastic Behavior From a Set of Representative Modes

2012 ◽  
Vol 135 (1) ◽  
Author(s):  
María A. Mayorca ◽  
Damian M. Vogt ◽  
Hans Mårtensson ◽  
Torsten H. Fransson
Keyword(s):  
Wide Frequency Range ◽  
Least Square ◽  
Mode Shapes ◽  
Frequency Range ◽  
Reduced Order ◽  
Transonic Compressor ◽  
Unsteady Aerodynamic ◽  
Shape Perturbation ◽  
Selection Of

A method is proposed for the determination of the aeroelastic behavior of a system responding to mode-shapes which are different from the tuned in vacuo ones, due to mistuning, mode family interaction, or any other source of mode-shape perturbation. The method is based on the generation of a data base of unsteady aerodynamic forces arising from the motion of arbitrary modes and uses least square approximations for the prediction of any responding mode. The use of a reduced order technique allows for mistuning analyses and is also applied for the selection of a limited number of arbitrary modes. The application of this method on a transonic compressor blade shows that the method captures the aeroelastic properties well in a wide frequency range. A discussion of the influence of the mode-shapes and frequency on the final stability response is also provided.

Selection of Component Modes for Craig-Bampton Substructure Representations

1996 ◽  
Vol 118 (2) ◽  
pp. 264-270 ◽  
Author(s):  
D. C. Kammer ◽  
M. J. Triller
Keyword(s):  
Efficient Method ◽  
Singular Values ◽  
General Purpose ◽  
Mode Shapes ◽  
Frequency Range ◽  
Reduced Representation ◽  
Absolute Measure ◽  
Fixed Interface ◽  
Interface Mode ◽  
Selection Of

Three measures of modal dynamic importance are studied for the purpose of ranking Craig-Bampton substructure fixed interface mode shapes based upon their contribution to forces at the substructure interface, modal velocity, or modal displacement. These measures can be employed to identify mode shapes which are dynamically important and thus should be retained in a reduced analytical representation, or identified during a modal survey of the substructure. The first method considered. Effective Interface Mass, has been studied previously. However, new results are presented showing the relation between Effective Interface Mass and a commonly used control dynamics measure of modal importance called approximate balanced singular values. In contrast to the general case of approximate balanced singular values, Effective Interface Mass always gives an absolute measure of the dynamic importance of mode shapes. The EIM method is extended to consider modal velocity and modal displacement outputs. All three measures are applied to a simple substructure called the General Purpose Spacecraft. It is shown that each of these measures provides an efficient method for ranking the dynamic importance of Craig-Bampton fixed interface modes such that a reduced representation will accurately reproduce the substructure’s response in the frequency range of interest.

The Use of Magnetostrictive Cores for the Vibrations Generation and Energy Harvesting from Vibration, in the Selected Frequencies of Work

2014 ◽  
Vol 598 ◽  
pp. 75-80 ◽  
Author(s):  
Jerzy Kaleta ◽  
Krzysztof Kot ◽  
Rafał Mech ◽  
Przemyslaw Wiewiorski
Keyword(s):  
Energy Transfer ◽  
Information Transfer ◽  
Wide Frequency Range ◽  
Frequency Range ◽  
Mechanical Vibrations ◽  
Energy Transportation ◽  
To Receive ◽  
Low Power Electronics ◽  
Time Selection ◽  
Selection Of

The paper presents research on use of magnetostrictive cores for the recovery of energy from vibrations and its use to power low-power electronics. To achieve this goal a test stand was constructed to generate and to receive the vibrations in the measurement system at the same time. Selection of an appropriate magnetomechanical parameters of the system was an important element influencing end results. The most important were values of the prestress and magnetising field for actuators and harvesters. As a result of the investigation the device operating in a wide frequency range (up to 40 KHz) and a system for energy transportation through mechanical vibrations were developed. Moreover it was shown that the proposed solution allow information transfer in a short bursts over the same system as energy transfer.

A New Reduced Order Modeling for Stability and Forced Response Analysis of Aero-Coupled Blades Considering Various Mode Families

2010 ◽  
Author(s):  
Mari´a A. Mayorca ◽  
Damian M. Vogt ◽  
Hans Ma˚rtensson ◽  
Torsten H. Fransson
Keyword(s):  
Single Mode ◽  
Forced Response ◽  
Least Square ◽  
Response Analysis ◽  
Computational Domain ◽  
Unsteady Forces ◽  
Reduced Order ◽  
Aerodynamic Damping ◽  
Transonic Compressor ◽  
Frequency Split

This paper presents the description and application of a new method for stability and forced response analyses of aerodynamically coupled blades considering the interaction of various mode families. The method, here referred as MLS (Multimode Least Square), considers the unsteady forces due to the blade motion at different modes shape families and calculates the aerodynamic matrixes by means of a least square (L2) approximations. This approach permits the prediction of mode families’ interaction with capabilities of structural, aerodynamic and force mistuning. A projection technique is implemented in order to reduce the computational domain. Application of the method on tuned and structural mistuned forced response and stability analyses is presented on a highly loaded transonic compressor blade. When considering structural mistuning the forced response amplitude magnification is highly affected by the change in aerodynamic damping due to mistuning. Analyses of structural mistuning without aerodynamic coupling might result in over-estimated or under-estimated response when the source of damping is mainly aerodynamic. The frequency split due to mistuning can cause that mode families’ interact due to reducing their frequencies separation. The advantage of the present method is that the effect of mode family interaction on aerodynamic damping and forced response is captured not being restricted to single mode families.

scholarly journals The determination of the information frequencies in the frame of the acoustic emission signals from the friction zone of tribosystems

2020 ◽  
Vol 97 (3) ◽  
pp. 6-13
Author(s):  
K. Fenenko ◽  
Keyword(s):  
Frequency Range ◽  
Friction Zone ◽  
Ae Signal ◽  
Operational Factors ◽  
Experimental Values ◽  
Effective Diagnosis ◽  
Friction Surfaces ◽  
Information Frequency ◽  
Selection Of

Based on the analysis of the works devoted to the selection of informative AE parameters for the diagnosis of tribosystems, in a theoretical way the information frequency ranges in the AE signal frame, where the maximum amplitudes values are observed, have been established. It has been theoretically and experimentally established that the information frequencies depend on the following groups of factors: the constructive; technological and operational ones. The degree of influence of the factors on the change in the frequency range is established. The operational factors (slip speed and load) change the frequency range from 106 to 584 kHz, the technological factors (roughness of the friction surfaces) change the frequency range from 118 to 618 kHz, the constructive factors (the size of the friction area of the stationary triboelement) change the frequency range from 140 to 530 kHz. It has been concluded that for the effective diagnosis of tribosystems, it is necessary to previously determine the information frequency range taking into account the factors listed above. The obtained results were confirmed experimentally with the calculation of the Fisher and Cochrane criteria, which allows one to state about the presence of a correlation between the theoretical values of the information frequencies generated by the tribosystem and the experimental values of the frequencies, where the maximum amplitudes were recorded, the correlation coefficient r = 0,88. The present analysis can be the basis for the development of a diagnostic method for tribosystems during their operation, which will increase the robustness and information content of the AE method.

scholarly journals Numerical and experimental assessment of a typical brazilian footbridge

2018 ◽  
Vol 11 (5) ◽  
pp. 1025-1035
Author(s):  
G. N. DOZ ◽  
J. L. V. BRITO ◽  
A. BRASILIANO
Keyword(s):  
Critical Frequency ◽  
Natural Frequencies ◽  
Experimental Tests ◽  
Vertical Vibration ◽  
Mode Shapes ◽  
Finite Element Models ◽  
Frequency Range ◽  
Precast Elements ◽  
Concrete Deck

Abstract For the range of medium spans, around 30 to 40m, composite footbridges are getting popular in Brazil. This kind of structure consists on longitudinal steel truss beams providing support for a concrete deck usually made of precast elements. Typical examples of these structures may be found in many cities in Brazil, especially in Brasilia where a large number of highways demanded a significant set of footbridges. Due to the amount of this kind of composite footbridges in Brazil, studies concerning their mechanical behavior are required in order to ensure pedestrian’s safety. For this end, in this paper, a typical Brazilian composite footbridge located in Brasilia is analyzed by means of experimental tests and computational modeling. The focus is the determination of natural frequencies and mode shapes. Strategies to correctly obtain the vertical modes are also discussed since vertical vibration is the main vibration problem expected for the tested footbridge. The obtained results showed that structural balance between stiffness and mass leads to natural frequencies out of the critical frequency range excited by pedestrians in normal use, although the idea was not to measure how these parameters, mass or stiffness, could influence the model. Moreover, Finite Element models were evaluated comparing complexity versus accuracy to predict modal parameters.

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