scholarly journals Modal analysis of 2-D sedimentary basin from frequency domain decomposition of ambient vibration array recordings

2014 ◽  
Vol 200 (1) ◽  
pp. 615-626 ◽  
Author(s):  
Valerio Poggi ◽  
Laura Ermert ◽  
Jan Burjanek ◽  
Clotaire Michel ◽  
Donat Fäh
Keyword(s):  
Domain Decomposition ◽  
Modal Analysis ◽  
Frequency Domain ◽  
Sedimentary Basin ◽  
Ambient Vibration ◽  
Frequency Domain Decomposition ◽  
Array Recordings

scholarly journals Operational Modal Analysis of a Spar-Type Floating Platform Using Frequency Domain Decomposition Method

Energies ◽  
2016 ◽  
Vol 9 (11) ◽  
pp. 870 ◽  
Author(s):  
Carlo Ruzzo ◽  
Giuseppe Failla ◽  
Maurizio Collu ◽  
Vincenzo Nava ◽  
Vincenzo Fiamma ◽  
...  
Keyword(s):  
Domain Decomposition ◽  
Modal Analysis ◽  
Frequency Domain ◽  
Decomposition Method ◽  
Domain Decomposition Method ◽  
Operational Modal Analysis ◽  
Floating Platform ◽  
Frequency Domain Decomposition

scholarly journals Operational Modal Analysis of Damage Gear

2020 ◽  
Vol 9 (3) ◽  
pp. 2778-2783
Keyword(s):  
Domain Decomposition ◽  
Modal Analysis ◽  
Frequency Domain ◽  
Dynamic Characteristics ◽  
Natural Frequencies ◽  
Helical Gear ◽  
Operational Modal Analysis ◽  
Mode Shapes ◽  
Identification Algorithm ◽  
Frequency Domain Decomposition

As natural frequencies and mode shapes are often a key to understanding dynamic characteristics of structural elements, modal analysis provides a viable means to determine these properties. This paper investigates the dynamic characteristics of a healthy and unhealthy condition of a commercially used helical gear using the Frequency Domain Decomposition (FDD) identification algorithm in Operational Modal Analysis (OMA). For the unhealthy condition, a refined range of percentage of defects are introduced to the helical gear starting from one (1) tooth being defected (1/60 teeth) to six (6) teeth being defected (6/60 teeth). The specimen is tested under a free-free boundary condition for its simplicity and direct investigation purpose. Comparison of the results of these varying conditions of the structure will be shown to justify the validity of the method used. Acceptable modal data are obtained by considering and accentuating on the technical aspects in processing the experimental data which are critical aspects to be addressed. The natural frequencies and mode shapes are obtained through automatic and manual peak-picking process from Singular Value Decomposition (SVD) plot using Frequency Domain Decomposition (FDD) technique and the results are validated using the established Modal Assurance Criterion (MAC) indicator. The results indicate that OMA using FDD algorithm is a good method in identifying the dynamic characteristics and hence, is effective in detection of defects in this rotating element

Ambient Response Modal Analysis on a CEM-1 Single-Layer Printed Circuit Board

2013 ◽  
Vol 393 ◽  
pp. 683-687
Author(s):  
M. Azhan Anuar ◽  
A.A. Mat Isa ◽  
A.R. Zamri ◽  
M.F.M. Said
Keyword(s):  
Domain Decomposition ◽  
Modal Analysis ◽  
Frequency Domain ◽  
Printed Circuit Boards ◽  
Printed Circuit Board ◽  
Single Layer ◽  
Circuit Board ◽  
Valuable Insight ◽  
Printed Circuit ◽  
Frequency Domain Decomposition

Since the level of vibration always depends on the natural frequencies of the system, it is important to know the modal parameters of such system to control failure and provide prevention actions. The demand for structurally reliable Printed Circuit Boards (PCB) has increased as more functions are required from electronic products along with less weight and smaller size. This imposes certain limitations and critical requirements. In this paper, investigation on the dynamic characteristics of CEM-1 Single-layer PCB using Operational Modal Analysis (OMA, or often called Output-Only or Ambient Modal analysis), is presented. The Frequency Domain Decomposition (FDD) and Enhanced Frequency Domain Decomposition (EFDD) techniques are applied on the PCB with free-free end condition. Comparison of results between both techniques and also with the result from Experimental Modal Analysis (EMA), will be shown. The understanding on dynamic behaviour of this structure provides valuable insight into the nature of the response and remarkable enhancement of its model, strength and vibration.

scholarly journals Análisis de métodos OMA para la extracción de parámetros modales sobre edificios existentes

2021 ◽  
Vol 33 (2) ◽  
pp. 75-93
Author(s):  
Víctor Samaniego Galindo ◽  
Iván Palacios Serrano ◽  
José Placencia León ◽  
Milton Muñoz Calle ◽  
Santiago González Martínez ◽  
...  
Keyword(s):  
Domain Decomposition ◽  
Modal Analysis ◽  
Frequency Domain ◽  
Operational Modal Analysis ◽  
Frequency Domain Decomposition

En este artículo se presenta la aplicación de métodos de análisis modal operacional (OMA, Operational Modal Analysis) con el objetivo de caracterizar los parámetros modales (v.g. frecuencias y modos de vibración) de una edificación. El estudio se realiza sobre un escenario real consistente en un edificio esencial. En concreto se emplea: el método de descomposición en el dominio de la frecuencia (FDD, Frequency Domain Decomposition) y su versión mejorada (EFDD, Enhanced-FDD). En una primera etapa, se lleva a cabo una evaluación estructural preliminar del edificio (empleando el método de inspección visual rápida, RVS), un levantamiento de dimensiones y ensayos en campo para la caracterización mecánica de sus componentes, todo ello con el propósito de conseguir un análisis modal convencional lo más fiable posible en términos de sus parámetros modales. Con base en este análisis modal, se diseña un plan de instrumentación con acelerómetros triaxiales de sistemas microelectromecánicos (MEMS); el proceso de instrumentación abarca tres etapas: la adquisición, el control y el almacenamiento de información. La principal contribución de este trabajo consiste en la evaluación de la aplicación de los métodos FDD y EFDD sobre un edificio esencial, con la particularidad del uso de vibraciones de microsismicidad para la identificación de parámetros modales. El análisis de los resultados obtenidos determina una frecuencia fundamental del edificio de 1.43 Hz, y evidencia un comportamiento modal no recomendado.

Higher order statistical frequency domain decomposition for operational modal analysis

2017 ◽  
Vol 84 ◽  
pp. 100-112 ◽  
Author(s):  
G.M. Nita ◽  
M.A. Mahgoub ◽  
S.G. Sharyatpanahi ◽  
N.C. Cretu ◽  
T.M. El-Fouly
Keyword(s):  
Domain Decomposition ◽  
Modal Analysis ◽  
Frequency Domain ◽  
Higher Order ◽  
Operational Modal Analysis ◽  
Statistical Frequency ◽  
Frequency Domain Decomposition

scholarly journals Monitoring Rock Slope Instabilities Using Frequency Domain Decomposition Modal Analysis

2021 ◽  
Author(s):  
Mauro Häusler ◽  
Clotaire Michel ◽  
Jan Burjánek ◽  
Donat Fäh
Keyword(s):  
Domain Decomposition ◽  
Resonance Frequency ◽  
Modal Analysis ◽  
Frequency Domain ◽  
Normal Mode ◽  
Rock Slope ◽  
Damping Ratio ◽  
Slope Instabilities ◽  
Frequency Domain Decomposition ◽  
Unstable Rock

<p>Measuring ambient seismic vibration provides a promising tool to monitor unstable rock slopes due to its independence from actual surface deformations. It is generally observed that the seismic wavefield, arising from ambient vibrations, polarizes perpendicular to open fractures and that unstable slopes exhibit strong wavefield amplifications compared to stable reference sites. Rock slope instabilities dominated by deep persistent fracture sets exhibit normal mode behaviour due to standing wave phenomena within individual compartments of the unstable volume. Techniques to assess such behavior are well established in mechanical and civil engineering to assess the dynamic response and possibly the structural integrity of the structure studied.</p><p> </p><p>We performed enhanced frequency domain decomposition modal analysis on ambient vibration data acquired in real-time on an unstable rock site with a volume larger than 150,000 m<sup>3</sup> near Preonzo, Switzerland. We tracked the resonance frequency and normal mode polarization of the first two modes over a period of four years. In addition, we show the development of the modal damping ratio of the fundental mode over time, which is a measure of energy dissipation within and out of the system. We found that the dynamic properties of the rock structure experienced annual variations and that they are primarily controlled by temperature and only secondarily by the exension and closure of large-scale fractures. Even though no large slope failure was observed during the monitoring period, the dataset provides a reference model for ongoing slope monitoring, as the resonance frequency and damping ratio is expected to change significantly prior to failure.</p>

scholarly journals Operational Modal Analysis on a 3D Scaled Model of a 3-Storey Aluminium Structure

2018 ◽  
Vol 7 (4.27) ◽  
pp. 78
Author(s):  
M. Fadhil Shazmir ◽  
N. Ayuni Safari ◽  
M. Azhan Anuar ◽  
A. A.Mat Isa ◽  
Zamri A.R
Keyword(s):  
Domain Decomposition ◽  
Modal Analysis ◽  
Frequency Domain ◽  
Natural Frequencies ◽  
Operational Modal Analysis ◽  
Mode Shapes ◽  
Modal Parameters ◽  
Modal Assurance Criterion ◽  
Scaled Model ◽  
Frequency Domain Decomposition

Obtaining a good experimental modal data is essential in modal analysis in order to ensure accurate extraction of modal parameters. The parameters are compared with other extraction methods to ascertain its consistency and validity. This paper demonstrates the extraction of modal parameters using various identification algorithms in Operational Modal Analysis (OMA) on a 3D scaled model of a 3-storey aluminium structure. Algorithms such as Frequency Domain Decomposition (FDD), Enhanced Frequency Domain Decomposition (EFDD) and Stochastic Subspace Identification (SSI) are applied in this study to obtain modal parameters. The model test structure is fabricated of aluminium and assembled using bolts and nuts. Accelerometers were used to collect the responses and the commercial post processing software was used to obtain the modal parameters. The resulting natural frequencies and mode shapes using FDD method are then compared with other OMA parametric technique such as EFDD and SSI algorithm by comparing the natural frequencies and Modal Assurance Criterion (MAC). Comparison of these techniques will be shown to justify the validity of each technique used and hence confirming the accuracy of the measurement taken.    

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