Vibration Testing and Modal Analysis of Airplanes – Recent Advances

2004 ◽  
Author(s):  
Bart Peeters ◽  
Antonio Vecchio ◽  
Thierry Olbrechts ◽  
Herman Van der Auweraer ◽  
Filip Lambert
Keyword(s):  
Modal Analysis ◽  
Vibration Testing ◽  
Recent Advances

Modal analysis of low-level-light aiming sight-glass based on vibration testing conditions

2009 ◽  
Author(s):  
Youtang Gao ◽  
Si Tian ◽  
Jianliang Qiao ◽  
Jun Niu ◽  
Benkang Chang
Keyword(s):  
Modal Analysis ◽  
Vibration Testing ◽  
Testing Conditions ◽  
Low Level

scholarly journals Recent advances of modal analysis in Japan.

1987 ◽  
Vol 30 (268) ◽  
pp. 1526-1533
Author(s):  
AKio NAGAMATSU
Keyword(s):  
Modal Analysis ◽  
Recent Advances

scholarly journals Operational modal analysis of mechanical systems using transmissibility functions in the presence of harmonics

2019 ◽  
Vol 13 (3) ◽  
pp. 1-14
Author(s):  
Van Dong Do ◽  
Thien Phu Le ◽  
Alexis Beakou
Keyword(s):  
White Noise ◽  
Modal Analysis ◽  
Gaussian White Noise ◽  
Harmonic Component ◽  
Operational Modal Analysis ◽  
Ambient Vibration ◽  
Response Analysis ◽  
Vibration Testing ◽  
Engineering Structures ◽  
Ambient Vibration Testing

Ambient vibration testing is a preferred technique for heath monitoring of civil engineering structures because of several advantages such as simple equipment, low cost, continuous use and real boundary conditions. However, the excitation not controlled and not measured, is always assumed as Gaussian white noise in the processing of ambient responses called operational modal analysis. In presence of harmonics due to rotating parts of machines or equipment inside the structures, e.g., fans or air-conditioners…, the white noise assumption is not verified and the response analysis becomes difficult and it can even lead to biased results. Recently, transmissibility function has been proposed for the operational modal analysis. Known as independent of excitation nature in the neighborhood of a system's pole, the transmissibility function is thus applicable in presence of harmonics. This study proposes therefore to apply the transmissibility functions for modal identification of ambient vibration testing and investigates its performance in presence of harmonics. Numerical examples and an experimental test are used for illustration and validation. Keywords: operational modal analysis; transmissibility function; harmonic component; ambient vibration testing.

A Method to Identify the Stiffness of Engine Mounts Using Experimental Modal Analysis

2005 ◽  
Author(s):  
Taro Tomatsu ◽  
Takeshi Okada ◽  
Tetsuro Ikeno ◽  
Kazuyuki Shiomi ◽  
Masaaki Okuma
Keyword(s):  
Modal Analysis ◽  
Thrust Force ◽  
Dynamic Stiffness ◽  
Element Model ◽  
Experimental Modal Analysis ◽  
New Method ◽  
Structural System ◽  
Vibration Testing ◽  
Engine Mounts ◽  
Actual Trial

This paper presents a new method for identifying the stiffness of engine mounts under the condition of being built in a structural system as in practical use. A conventionally standard method is to use a dynamic stiffness measurement equipment that can deal with only an individual mount. In the new method, the stiffness values of mounts built in a structural system are identified using the modal parameters of the system which are obtained by experimental modal analysis. Vibration testing of the structural system in an operational condition can make it possible to consider preload effect caused by the gravitational and driving force, such as thrust force, applied to the structural system. Additionally, vibration testing using an impact hammer is widely available so that the new method can make it much easier to identify the stiffness of mounts in various situations than the conventional method. In this paper, the validity of the method is demonstrated using both a simulation study using a finite element model and an actual trial for an actual outboard engine. The result shows the dependence of the mount stiffness on the gravitational force and the thrust force at the propeller of the outboard engine.

Recent Advances in High Dispersion Spectroscopy of Globular Cluster Stars

1988 ◽  
Vol 132 ◽  
pp. 525-530
Author(s):  
Raffaele G. Gratton
Keyword(s):  
Globular Cluster ◽  
Globular Clusters ◽  
High Dispersion ◽  
Photographic Material ◽  
Recent Advances ◽  
Metal Abundances ◽  
Ccd Detectors ◽  
Major Progress

The use CCD detectors has allowed a major progress in abundance derivations for globular cluster stars in the last years. Abundances deduced from high dispersion spectra now correlates well with other abundance indicators. I discuss some problems concerning the derivation of accurate metal abundances for globular clusters using high dispersion spectra from both the old photographic and the most recent CCD data. The discrepant low abundances found by Cohen (1980), from photographic material for M71 giants, are found to be due to the use of too high microturbulences.

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