scholarly journals Experimental Modal Analysis of an Aircraft Wing Prototype for SAE Aerodesign Competition

DYNA ◽  
2020 ◽  
Vol 87 (214) ◽  
pp. 100-110
Author(s):  
Victor E.L Gasparetto ◽  
Marcela Machado ◽  
Sergio H.S. Carneiro
Keyword(s):  
Modal Analysis ◽  
Ground Vibration ◽  
Experimental Modal Analysis ◽  
Modal Identification ◽  
Modal Parameters ◽  
Aircraft Wing ◽  
Modal Assurance Criterion ◽  
Response Data ◽  
Modes Of Vibration ◽  
The University

This work presents an experimental modal analysis of an aircraft wing prototype, designed by the Aerodesign team of the University of Brasilia, and performs a ground vibration testing of the prototype. The dynamic response data were acquired using the software LabVIEW, and the modal parameters were identified through the EasyMod toolbox. The modal parameters are characterised for the first seven vibration modes of the structure, with the firsts two being suspension modes of vibration. The effect of small changes in the experimental procedure on the identified modal parameters is discussed. It was observed that the use of an excitation signal as a logarithmic sine sweep and with a frequency range of excitation between 2 to 150 Hz resulted in less noise and more accurate measurement of the structure’s response. Results for different modal identification methods were verified using the Modal Assurance Criterion (MAC), and good correlation was achieved.

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-).

scholarly journals Transmissibilty-Based Operational Modal Analysis for Flight Flutter Testing Using Exogenous Inputs

2012 ◽  
Vol 19 (5) ◽  
pp. 1071-1083 ◽  
Author(s):  
Christof Devriendt ◽  
Tim De Troyer ◽  
Gert De Sitter ◽  
Patrick Guillaume
Keyword(s):  
Modal Analysis ◽  
Frequency Domain ◽  
Experimental Modal Analysis ◽  
Operational Modal Analysis ◽  
Modal Parameters ◽  
Input Output ◽  
Output Only ◽  
Flutter Testing

During the recent years several new tools have been introduced by the Vrije Universiteit Brussel in the field of Operational Modal Analysis (OMA) such as the transmissibility based approach and the the frequency-domain OMAX concept. One advantage of the transmissibility based approach is that the ambient forces may be coloured (non-white), if they are fully correlated. The main advantage of the OMAX concept is the fact that it combines the advantages of Operational and Experimental Modal Analysis: ambient (unknown) forces as well as artificial (known) forces are processed simultaneously resulting in improved modal parameters. In this paper, the transmissibility based output-only approach is combined with the input/output OMAX concept. This results in a new methodology in the field of operational modal analysis allowing the estimation of (scaled) modal parameters in the presence of arbitrary ambient (unknown) forces and artificial (known) forces.

Experimental Modal Analysis of Car's Body-in-White

2011 ◽  
Vol 346 ◽  
pp. 627-633 ◽  
Author(s):  
He Li ◽  
Shi Bo Fu ◽  
Bang Chun Wen
Keyword(s):  
Modal Analysis ◽  
Single Point ◽  
Test System ◽  
Experimental Modal Analysis ◽  
Modal Parameters ◽  
Modal Characteristics ◽  
Car Body ◽  
Modal Test ◽  
Acceleration Sensors ◽  
Body In White

To reduce noise and make the structure of the car more rational, we established modal test system of car's body-in-white in this paper. Car body-in-white was mounted on rigid platform with four coil springs. The car was excited by an electromagnetic exciter. The method of single-point excitation and multi-point collecting vibration was used in this test. Excitation point was chosen in the bearing beam. Signals picked up by the acceleration sensors were processed in the software of Mescope. With this system, different modal frequencies and modal characteristics of the car are acquired. The results show that modal parameters are effective and reliable and those parameters can be basis for the designer to improve the structure of the car.

scholarly journals Influence of Crack on Modal Parameters of Cantilever Beam Using Experimental Modal Analysis

2018 ◽  
Vol 1 (1) ◽  
pp. 16-23 ◽  
Author(s):  
Siva Sankara Babu Chinka ◽  
Balakrishna Adavi ◽  
Srinivasa Rao Putti
Keyword(s):  
Numerical Analysis ◽  
Modal Analysis ◽  
Natural Frequency ◽  
Cantilever Beam ◽  
Damping Ratio ◽  
Crack Depth ◽  
Experimental Modal Analysis ◽  
Mode Shapes ◽  
Modal Parameters ◽  
Crack Location

In this paper, the dynamic behavior of a cantilever beam without and with crack is observed. An elastic Aluminum cantilever beams having surface crack at various crack positions are considered to analyze dynamically. Crack depth, crack length and crack location are the foremost parameters for describing the health condition of beam in terms of modal parameters such as natural frequency, mode shape and damping ratio. It is crucial to study the influence of crack depth and crack location on modal parameters of the beam for the decent performance and its safety. Crack or damage of structure causes a reduction in stiffness, an intrinsic reduction in resonant frequencies, variation of damping ratios and mode shapes. The broad examination of cantilever beam without crack and with crack has been done using Numerical analysis (Ansys18.0) and experimental modal analysis. To observe the exact higher modes of beam, discretize the beam into small elements. An experimental set up was established for cantilever beam having crack and it was excited by an impact hammer and finally the response was obtained using PCB accelerometer with the help sound and vibration toolkit of NI Lab-view. After obtaining the Frequency response functions (FRFs), the natural frequencies of beam are estimated using peak search method. The effectiveness of experimental modal analysis in terms of natural frequency is validated with numerical analysis results. This paper contains the study of free vibration analysis under the influence of crack at different points along the length of the beam.

scholarly journals Experimental modal analysis for the plate structures with roving inertial shaker method approach

2021 ◽  
pp. 146134842110393
Author(s):  
Erdi Gülbahçe ◽  
Mehmet Çelik
Keyword(s):  
Modal Analysis ◽  
Position Effect ◽  
Experimental Modal Analysis ◽  
Modal Parameters ◽  
Response Functions ◽  
Plate Structures ◽  
Stabilization Diagram ◽  
Method Approach ◽  
High Test ◽  
Correlation Rate

In this article, a new roving inertial shaker method approach, using an inertial shaker, is presented to obtain a steel plate’s modal parameters with bolt connections on four sides. It aimed to emphasize the superiority of the proposed roving shaker approach over the classical, traditional hammer method on the plate-like structures. The frequency response functions (FRF), obtained from both methods, are investigated using the stabilization diagram, and the superiority of the roving shaker method is presented based on high stabilization and detecting more modes. The accelerometer’s position effect on experimental modal analysis (EMA) is investigated in the roving shaker method, which is performed using accelerometers in two different places, and obtained modal parameters are compared with experimental modal analysis validation methods. Accordingly, the results for the two separate locations are very close to each other. Finally, the experimental and numerical results are investigated according to the TEST/FEA correlation for the traditional roving hammer method and the roving shaker method. As a result, the roving shaker approach gives a better result according to the TEST/FEA correlation success than the roving hammer test. In conclusion, the high stabilization, high TEST/FEA correlation rate, and the number of modes show the roving shaker approach’s superiority.

“Errors-in-Variables” Identification Techniques Applied to Modal Analysis

1997 ◽  
Author(s):  
Patrick Guillaume
Keyword(s):  
Maximum Likelihood ◽  
Modal Analysis ◽  
Experimental Modal Analysis ◽  
Modal Parameters ◽  
Errors In Variables ◽  
Parametric Case ◽  
Identification Techniques

Abstract The present paper introduces maximum likelihood “errors-in-variables” identification techniques in the field of experimental modal analysis. The nonparametric (i.e. the estimation of the FRF’s) as well as the parametric case (i.e. the estimation of the modal parameters) are considered.

Sign in / Sign up

Export Citation Format

Share Document