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

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.    

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 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.

scholarly journals DYNAMIC BEHAVIOR OF A CABLE-STAYED FOOTBRIDGE OVER RIVER VRBAS IN BANJA LUKA

2020 ◽  
Vol 14 (1) ◽  
Author(s):  
Marina Latinović ◽  
Zoran Mišković ◽  
Marko Popović
Keyword(s):  
Domain Decomposition ◽  
Modal Analysis ◽  
Frequency Domain ◽  
Dynamic Behavior ◽  
Mode Shapes ◽  
Modal Parameters ◽  
Fe Model ◽  
Modal Assurance Criterion ◽  
Frequency Domain Decomposition ◽  
Banja Luka

This paper presents a dynamic behavior analysis of an old cable-stayed footbridge over river Vrbasin Banja Luka. Identification of modal parameters, of this prone to vibrations footbridge structure,was performed using Operational Modal Analysis with Frequency Domain Decomposition method.Experimental test setups and obtained results, compared to the numerical values obtained by FEmodel updating, are shown. Modal Assurance Criterion was used for the confirmation of theuniqueness of experimentally obtained mode shapes, and also for the comparison of FE model modeshapes to the experimentally obtained ones, in the locations of measurement.

FEA on Vibration Characteristics of a Shrouded Turbine Blade

2012 ◽  
Vol 189 ◽  
pp. 443-447
Author(s):  
Wei Qiang Zhao ◽  
Yong Xian Liu ◽  
Mo Wu Lu
Keyword(s):  
Optimal Design ◽  
Modal Analysis ◽  
Turbine Blade ◽  
Dynamic Characteristics ◽  
Natural Frequencies ◽  
Vibration Characteristics ◽  
Mode Shapes ◽  
Software Environment ◽  
Aero Engine ◽  
Characteristics Analysis

This paper introduces a FEA method for vibration characteristics analysis of an aero-engine shrouded turbine blade and makes an actual modal analysis of this shrouded blade based on this method in UG software environment. The first six natural frequencies and mode shapes of this shrouded blade are calculated. And also, the dynamic characteristics of the shrouded turbine blade are discussed in detail according to the analysis results. The FEA method and the vibration characteristics analysis results in the paper can be used for optimal design and vibration safety verification of this aero-engine shrouded turbine blade.

scholarly journals Dynamic Characteristics of an Elastic Structure with Thermal Effects

2020 ◽  
Vol 25 (2) ◽  
pp. 200-208
Author(s):  
Guanhua Xu ◽  
Jianzhong Fu ◽  
Wen He ◽  
Yuetong Xu ◽  
Zhiwei Lin ◽  
...  
Keyword(s):  
Modal Analysis ◽  
Dynamic Characteristics ◽  
Thermal Effects ◽  
Natural Frequencies ◽  
Elastic Structure ◽  
Mode Shapes ◽  
The Finite Element Method ◽  
Environmental Testing ◽  
Temperature Changes ◽  
Property Changes

The vibration table in a combination environmental testing device suffers from temperature changes, which cause the dynamic characteristics of the vibration structure to vary. The mechanism of the thermal effect on the dynamic characteristics of an elastic structure is presented, and a modal analysis with thermal effects based on the finite-element method (FEM) is carried out. The results show that the natural frequencies for each order decrease as the temperature increases, while the mode shapes of the vibrator do not change with temperature. Although thermal stress may affect natural frequencies due to the additional initial stress element stiffness, this stress can be neglected in the modal analysis because it is negligible relative to the effect of the material property changes with temperature.

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