Experimental Modal Analysis of a Suspension Assembly Loaded on a Rotating Disk

1994 ◽  
Vol 116 (1) ◽  
pp. 85-92 ◽  
Author(s):  
C. J. Wilson ◽  
D. B. Bogy
Keyword(s):  
Modal Analysis ◽  
Natural Frequency ◽  
Rotating Disk ◽  
Disk Drive ◽  
Experimental Modal Analysis ◽  
Modal Parameters ◽  
Resonant Frequencies ◽  
Analysis System ◽  
Computer Disk

An experimental modal analysis system, which has been shown to be effective in the study of small structures, is utilized to analyze the interaction of the disk and the suspension assembly in a computer disk drive. A thorough understanding of the interaction of these structures is obtained by determining the modal parameters for each of the components in an uncoupled state and in a coupled state with the disk both stationary and rotating. It is shown that when a natural frequency of the suspension is close to that of the disk, two system resonant frequencies are created when the components are coupled together.

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.

An Experimental Modal Analysis Technique for Miniature Structures

1996 ◽  
Vol 118 (1) ◽  
pp. 1-9 ◽  
Author(s):  
C. J. Wilson ◽  
D. B. Bogy
Keyword(s):  
Modal Analysis ◽  
Laser Doppler Vibrometer ◽  
Element Model ◽  
Experimental Modal Analysis ◽  
Modal Parameters ◽  
Computational Results ◽  
Magnetic Actuator ◽  
Analysis Technique ◽  
Excitation Force ◽  
Analysis System

This paper describes an experimental modal analysis system which can effectively be used to obtain the modal parameters of small structures. The system uses an electromagnetic exciter to produce the excitation force, a piezoelectric transducer to measure this force, and a Laser Doppler Vibrometer to measure the response. Several designs of the magnetic actuator are discussed and evaluated. The system is verified by obtaining the modal parameters of a miniature cantilever plate, using two preferred exciter designs, and comparing the measured parameters with those acquired from a finite element model. Favorable agreement is obtained between the experimental and computational results. Finally, the two preferred exciters are compared and an optimal configuration is discussed.

Experimental Modal Analysis of Compressor Vibration Isolating System Based on LMS Test.Lab

2011 ◽  
Vol 121-126 ◽  
pp. 3283-3288
Author(s):  
Li Zhang ◽  
Hao Chen ◽  
Yan Jue Gong ◽  
Jing Wang
Keyword(s):  
Resonance Frequency ◽  
Modal Analysis ◽  
Natural Frequency ◽  
Single Layer ◽  
Experimental Modal Analysis ◽  
Impact Testing ◽  
Modal Parameters ◽  
Isolation System ◽  
Refrigeration Unit ◽  
Comparison Results

In order to reduce vibration and noise of the compressor used in small and medium-sized refrigeration unit, this paper designs different vibration isolating systems and carries out experimental modal analysis based on LMS Test. Lab Impact Testing software. The comparison results of modal parameters of four different vibration isolating systems show that the natural frequency of single-layer vibration isolating system is higher than that of non-isolation system and effectively avoids the second order resonance frequency. Furthermore the natural frequency of double-layer vibration isolating system has reduced due to the additional middle-mass. And the system's natural frequency decreases obviously with the increase of middle-mass which is far from resonance frequency and significantly improve the effect of vibration isolating system.

Experimental Modal Analysis of Rotating Disk Systems

1995 ◽  
Author(s):  
Horst Irretier ◽  
Frank Reuter
Keyword(s):  
Modal Analysis ◽  
Circular Disk ◽  
Rotating Disk ◽  
Experimental Modal Analysis ◽  
Mode Shapes ◽  
Modal Parameters ◽  
Response Functions ◽  
Testing Technique ◽  
Theoretical Frequency ◽  
Modal Damping

Abstract A completely non-contact testing technique is presented to perform experimental modal analysis on rotating disk systems to identify modal parameters as eigenfrequencies, modal damping ratios and mode shapes due to rotation. Theoretical frequency response functions of rotating structures are presented which form the basis of the modal analysis. Experimental results of a rotating circular disk and a rotating radial impeller are presented and the influence of rotation on the modal parameters due to centrifugal, gyroscopic and aerodynamic effects is shown.

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 Crack Identification and Localization In Structural Beams Using Numerical and Experimental Modal Analysis- A Review

2020 ◽  
pp. 62-68
Keyword(s):  
Modal Analysis ◽  
Natural Frequency ◽  
Structural Damage ◽  
Experimental Modal Analysis ◽  
Mode Shapes ◽  
Crack Identification ◽  
Engineering Structures ◽  
Aircraft Wings ◽  
Crack Location ◽  
Damaged Beams

This article presents a critical review of recent research done on crack identification and localization in structural beams using numerical and experimental modal analysis. Crack identification and localization in beams are very crucial in various engineering applications such as ship propeller shafts, aircraft wings, gantry cranes, and Turbo machinery blades. It is necessary to identify the damage in time; otherwise, there may be serious consequences like a catastrophic failure of the engineering structures. Experimental modal analysis is used to study the vibration characteristics of structures like natural frequency, damping and mode shapes. The modal parameters like natural frequency and mode shapes of undamaged and damaged beams are different. Based on this reason, structural damage can be detected, especially in beams. From the review of various research papers, it is identified that a lot of the research done on beams with open transverse crack. Crack location is identified by tracking variation in natural frequencies of a healthy and cracked beam

Application of Experimental Modal Analysis Method in Researching of Mechanical Structure Dynamic Characteristics

2013 ◽  
Vol 694-697 ◽  
pp. 370-373
Author(s):  
Zhang Yu ◽  
Wen Zheng Cai
Keyword(s):  
Modal Analysis ◽  
Natural Frequency ◽  
Dynamic Characteristics ◽  
High Speed ◽  
Experimental Modal Analysis ◽  
Analysis Method ◽  
Mechanical Structure ◽  
Vibration Resistance ◽  
Structural Rigidity ◽  
Structure Dynamic

With the purpose of realizing the analysis of mechanical structure dynamic characteristics and inhibit vibration and noise, combined with the analysis of a certain type of high speed sewing machines vibration characteristics, we carry on the concrete experimental modal analysis, and compare the results of the experimental modal analysis with the results of spectrum analysis. The analysis results show that the second order natural frequency of the shell is close to two octaves under the normal working speed of sewing machine and it will lead to resonance. Enhancing the structural rigidity and the natural frequency under this modal to avoid resonance frequency is the key to improve vibration resistance of the structure.

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.

Sign in / Sign up

Export Citation Format

Share Document