Identification of Modal Parameters of an Elastic Rotor With Oil Film Bearings

1984 ◽  
Vol 106 (1) ◽  
pp. 107-112 ◽  
Author(s):  
Rainer Nordmann
Keyword(s):  
Modal Analysis ◽  
Dynamic Behavior ◽  
Design Process ◽  
Mechanical Engineering ◽  
Mechanical Systems ◽  
Rotating Machinery ◽  
Modal Parameters ◽  
Powerful Method ◽  
Oil Film ◽  
Engineering Problems

Investigations of the dynamic behavior of structures have become increasingly important in the design process of mechanical systems. To have a better understanding of the dynamic behavior of a structure, the knowledge of the modal parameters is very important. The powerful method of experimental modal analysis has been used to measure modal parameters in many mechanical engineering problems. But the method was mainly applied to nonrotating structures. This presentation shows improvements of the classical modal analysis for a successful application in rotating machinery with nonconservative effects. An example is given, investigating the modal parameters of an elastic rotor with oil film bearings.

scholarly journals Comparison of Mode Shapes of Carbon-Fiber-Reinforced Plastic Material Considering Carbon Fiber Direction

Crystals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 311
Author(s):  
Chan-Jung Kim
Keyword(s):  
Carbon Fiber ◽  
Modal Analysis ◽  
Dynamic Behavior ◽  
Mode Shapes ◽  
Modal Parameters ◽  
Carbon Fiber Reinforced Plastic ◽  
Fiber Direction ◽  
Fiber Reinforced ◽  
Fiber Reinforced Plastic ◽  
Reinforced Plastic

Previous studies have demonstrated the sensitivity of the dynamic behavior of carbon-fiber-reinforced plastic (CFRP) material over the carbon fiber direction by performing uniaxial excitation tests on a simple specimen. However, the variations in modal parameters (damping coefficient and resonance frequency) over the direction of carbon fiber have been partially explained in previous studies because all modal parameters have only been calculated using the representative summed frequency response function without modal analysis. In this study, the dynamic behavior of CFRP specimens was identified from experimental modal analysis and compared five CFRP specimens (carbon fiber direction: 0°, 30°, 45°, 60°, and 90°) and an isotropic SCS13A specimen using the modal assurance criterion. The first four modes were derived from the SCS13A specimen; they were used as reference modes after verifying with the analysis results from a finite element model. Most of the four mode shapes were found in all CFRP specimens, and the similarity increased when the carbon fiber direction was more than 45°. The anisotropic nature was dominant in three cases of carbon fiber, from 0° to 45°, and the most sensitive case was found in Specimen #3.

Dynamic Behavior of Rolling Tires Under Different Operating Conditions

2012 ◽  
Author(s):  
S. Vercammen ◽  
C. González Díaz ◽  
P. Kindt ◽  
C. Thiry ◽  
J. Middelberg ◽  
...  
Keyword(s):  
Wave Propagation ◽  
Modal Analysis ◽  
Dynamic Behavior ◽  
Operating Conditions ◽  
Operational Modal Analysis ◽  
Modal Parameters ◽  
Road Noise ◽  
Vibration Measurements ◽  
Noise And Vibration ◽  
Propagation Behavior

Although tire/road noise and tire vibration phenomena have been studied for decades, there are still some missing links in the process of accurately predicting and controlling the overall tire/road noise and vibration. An important missing link is represented by the effect of rolling on the dynamic behavior of a tire. Consequently, inside the European seventh framework program, an industry-academia partnership project, named TIRE-DYN, has been founded between KU Leuven, Goodyear and LMS International. By means of experimental and numerical analyses, the effects of rolling on the tire dynamic behavior are quantified. This paper presents the results of vibration measurements on a rotating tire with an embedded accelerometer. Modal parameters of the rolling tire are estimated from an operational modal analysis. In addition, the dispersion curves, which give detailed insight in the wave propagation behavior of a structure, are analyzed for the rolling tire. The goal of these analyses is to deepen the understanding on the influence of rolling on the tire dynamic behavior.

Vibrational Analysis of a Dual-Motive Locomotive and Evaluation by Experimental Methods and Modal Analysis

2012 ◽  
Author(s):  
Jesús Otero Yugat ◽  
Gorka Agirre Castellanos ◽  
Igor Alonso Portillo
Keyword(s):  
Modal Analysis ◽  
Dynamic Behavior ◽  
Dynamic Properties ◽  
Vibrational Excitation ◽  
Vibrational Analysis ◽  
Experimental Methods ◽  
Mode Shapes ◽  
Modal Parameters ◽  
Hydraulic Actuator ◽  
Diesel Locomotive

This paper presents a theoretical and experimental study done on an electro-diesel locomotive in order to evaluate the dynamic behavior of the vehicle in terms of safety, running performance and wheel-track interaction. The vibration analysis has been made by means of different experimental methodologies. The first one consists on the acquisition of accelerations at points located at the wheelset, the truck frame and the coach, using piezorresistive accelerometers. The registered signals allow to validate the locomotive in terms of safety against derailment and running behavior, according the UIC 518 leaflet. The second method is based on the modal analysis theory and includes the dynamic properties estimation under vibrational excitation. This procedure takes into account the determination of modal parameters such as natural frequencies, modal damping ratios and mode shapes, by means of a control hydraulic actuator. The third methodology consists on the operational modal analysis done with the experimental measurements acquired on track tests, in order to validate the results obtained by modal analysis and evaluate the dynamic behavior under different speed ranges and cant deficiencies. Several tests have been done by means of the described methods in an electro-diesel locomotive composed by a primary suspension with dampers and a secondary suspension with rigid stiffness. In addition, two types of dampers have been evaluated with the purpose of optimizing the damping properties of the vehicle’s primary suspension. Through these experimental methods, a useful tool for the prediction and analysis of the dynamic behavior is provided. Additionally, the results obtained by means of these methodologies permit examining the influence of different running conditions and vehicle properties on the modal parameters.

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.

Innovative Approach for Teaching Graphical Engineering Focused on CAD/CAM/CAE Systems

2013 ◽  
Vol 572 ◽  
pp. 311-314
Author(s):  
Juan Carlos Pérez-Cerdán ◽  
Miguel Lorenzo ◽  
Alejandro Reveriego ◽  
Carmen Blanco
Keyword(s):  
Design Process ◽  
Mechanical Engineering ◽  
Innovative Approach ◽  
Structural Components ◽  
New Approach ◽  
Engineering School ◽  
Engineering Problems ◽  
Cad Cam ◽  
The Subject ◽  
The University

A new approach of the teaching of the subject Graphical engineering is developed at the Engineering School of the University of Salamanca, focusing the contents on the use of the CAD/CAM/CAE systems as useful tools for applying engineering problems related with the mechanical engineering instead of describing diverse software options. Thus, the contents of the subject are divided into two blocks, one devoted to the analysis of the results of simulation of movement of diverse mechanisms and the second devoted to the analysis of diverse cases of loading structural components by means of FEA module, both available in the Autodesk Inventor Pro suite which can be downloaded free by the students. This way, students can visualize and realize of the complexity of a design process in engineering.

Experimental Modal Characterization of MEMS Switches

2011 ◽  
Vol 403-408 ◽  
pp. 4598-4605
Author(s):  
Joel M. Book ◽  
Samuel F. Asokanthan ◽  
Tian Fu Wang
Keyword(s):  
Modal Analysis ◽  
Mechanical Systems ◽  
Noise Signal ◽  
Experimental Modal Analysis ◽  
Modal Parameters ◽  
Mems Devices ◽  
Micro Electro Mechanical Systems ◽  
Mems Switches ◽  
Stochastic Subspace Identification

MEMS devices, Micro Electro-Mechanical Systems, are electrical and mechanical systems with characteristic dimensions on the order of microns. Since these systems have moving mechanical parts, characterization of their dynamics, including their modal parameters, is highly desirable. This paper describes the validation of an existing implementation of the Stochastic Subspace Identification (SSI) algorithm, called MACEC, for experimental modal analysis of a micro-cantilever switch. A white noise signal applied to the built-in electrostatic actuator in the switches excited a response measured using microscanning Laser Doppler Vibrometry (LDV). The modal parameters found using MACEC matched well those predicted by theory, thus validating this combination for experimental modal analysis of MEMS structures.

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 Identification of modal parameters of machine tools during cutting by operational modal analysis

Procedia CIRP ◽  
2018 ◽  
Vol 77 ◽  
pp. 473-476 ◽  
Author(s):  
Jan Berthold ◽  
Martin Kolouch ◽  
Volker Wittstock ◽  
Matthias Putz
Keyword(s):  
Modal Analysis ◽  
Machine Tools ◽  
Operational Modal Analysis ◽  
Modal Parameters
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