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

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 Performance of Camera-Based Vibration Monitoring Systems in Input-Output Modal Identification Using Shaker Excitation

2021 ◽  
Vol 13 (17) ◽  
pp. 3471
Author(s):  
Maksat Kalybek ◽  
Mateusz Bocian ◽  
Wojciech Pakos ◽  
Jacek Grosel ◽  
Nikolaos Nikitas
Keyword(s):  
Image Processing ◽  
Modal Analysis ◽  
Experimental Modal Analysis ◽  
Modal Identification ◽  
Vibration Monitoring ◽  
Mode Shapes ◽  
Monitoring Systems ◽  
Input Output ◽  
Engineering Structures ◽  
Scaled Model

Despite significant advances in the development of high-resolution digital cameras in the last couple of decades, their potential remains largely unexplored in the context of input-output modal identification. However, these remote sensors could greatly improve the efficacy of experimental dynamic characterisation of civil engineering structures. To this end, this study provides early evidence of the applicability of camera-based vibration monitoring systems in classical experimental modal analysis using an electromechanical shaker. A pseudo-random and sine chirp excitation is applied to a scaled model of a cable-stayed bridge at varying levels of intensity. The performance of vibration monitoring systems, consisting of a consumer-grade digital camera and two image processing algorithms, is analysed relative to that of a system based on accelerometry. A full set of modal parameters is considered in this process, including modal frequency, damping, mass and mode shapes. It is shown that the camera-based vibration monitoring systems can provide high accuracy results, although their effective application requires consideration of a number of issues related to the sensitivity, nature of the excitation force, and signal and image processing. Based on these findings, suggestions for best practice are provided to aid in the implementation of camera-based vibration monitoring systems in experimental modal analysis.

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-).

The Use of Modan 3D in Experimental Modal Analysis

2013 ◽  
Vol 486 ◽  
pp. 36-41 ◽  
Author(s):  
Róbert Huňady ◽  
František Trebuňa ◽  
Martin Hagara ◽  
Martin Schrötter
Keyword(s):  
Modal Analysis ◽  
Vibration Analysis ◽  
High Speed ◽  
Mechanical Vibration ◽  
Steel Sample ◽  
Experimental Modal Analysis ◽  
Image Correlation ◽  
Optical Methods ◽  
Mode Shapes ◽  
Vibration Modes

Experimental modal analysis is a relatively young part of dynamics, which deals with the vibration modes identification of machines or their parts. Its development has started since the beginning of the eighties, when the computers hardware equipment has improved and the fast Fourier transform (FFT) could be used for the results determination. Nowadays it provides an uncountable set of vibration analysis possibilities starting with conventional contact transducers of acceleration and ending with modern noncontact optical methods. In this contribution we mention the use of high-speed digital image correlation by experimental determination of mode shapes and modal frequencies. The aim of our work is to create a program application called Modan 3D enabling the performing of experimental modal analysis and operational modal analysis. In this paper the experimental modal analysis of a thin steel sample performed with Q-450 Dantec Dynamics is described. In Modan 3D the experiment data were processed and the vibration modes were determined. The reached results were verified by PULSE modulus specialized for mechanical vibration analysis.

AN INVESTIGATION ON LIGHT STRUCTURE MODAL PARAMETER BY USING EXPERIMENTAL MODAL ANALYSIS METHOD VIA PIEZOFILM SENSOR

2017 ◽  
Vol 79 (6) ◽  
Author(s):  
Mohd Irman Ramli ◽  
Mohd. Zaki Nuawi ◽  
Shahrum Abdullah ◽  
Mohammad Rasidi Mohammad Rasani ◽  
Muhamad Arif Fadli Ahmad ◽  
...  
Keyword(s):  
Modal Analysis ◽  
Natural Frequency ◽  
Experimental Work ◽  
Mode Shapes ◽  
Piezoelectric Film ◽  
Modal Parameter ◽  
Film Sensor ◽  
Work Outcome ◽  
The Status ◽  
Experimental Approaches

This study is conducted to determine the modal parameters namely natural frequencies and mode shapes of aluminum 6061 (Al6061). The parameters are done by conducting a free dynamic vibration analysis. Modal analysis study was conducted by both simulation and experimental approaches. The simulation was conducted via ANSYS software while the experimental work was performed through impact hammer testing to determine the vibration parameter. Two sensors i.e. piezoelectric film and accelerometer were used. The result obtained were ya = 302.02x – 52.51 (accelerometer) and yp = 295.78x - 41.73 (piezofilm). ya (accelerometer) and yp (piezofilm) is linear equation of the data plotted according to the reading from mode shape versus natural frequency. The relation between natural frequency from accelerometer and piezofilm for the rectangular-shaped specimen was ya = 1.02yp – 9.90 and can be concluded that the regression ratio of 1.02 was approximately 1.0 which agreed with the status of piezoelectric film sensor that can be used as an alternative sensor for accelerometer. There was a good results agreement between simulation and experimental work outcome.

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.

Effect of Weight on the Experimental Modal Analysis of Slender Cantilever Beams

2009 ◽  
Author(s):  
Lawrence Virgin ◽  
David Holland
Keyword(s):  
Modal Analysis ◽  
Natural Frequencies ◽  
Vertical Direction ◽  
Experimental Modal Analysis ◽  
Mode Shapes ◽  
Lateral Stiffness ◽  
Axial Loads ◽  
Horizontal Orientation ◽  
Beam System ◽  
Tensile Forces

It is relatively well known that axial loads tend to influence lateral stiffness and hence natural frequencies of slender structural components. Tensile forces tend to increase the lateral stiffness and compressive forces tend to reduce lateral stiffness, bringing with it the possibility of buckling. In many practical situations this is a negligible effect. But for very slender structures it can be important, including the effect of self-weight. This paper will focus attention on a form of double cantilever beam system, i.e., two cantilevers sharing a common hub. A differential axial load can be applied to this system via orientation in a gravitational field. We shall neglect the effect of gravity when the beams are in their horizontal orientation from a limited theoretical standpoint. It is of course present in the experiments but the cantilevers are much stiffer in one direction than the other, and the beams are clamped with their stiffer resistance in the vertical direction. The focus of the current paper is on the natural frequencies and mode shapes of a two-beam system from an experimental modal analysis perspective.

scholarly journals Rayleigh Damping Coefficients of Laminated Rubber Bearing

2019 ◽  
Vol 8 (4) ◽  
pp. 12294-12300
Keyword(s):  
Finite Element ◽  
Modal Analysis ◽  
Natural Frequencies ◽  
Experimental Modal Analysis ◽  
Mode Shapes ◽  
Ground Structure ◽  
Damping Coefficients ◽  
Rubber Bearing ◽  
Stability And Instability ◽  
Laminated Rubber Bearing

In isolating the ground structure and the above ground structure from seismic loads, a significant device called laminated rubber bearing is usually found in structure. The complexity of the material which is made up from a combination of rubber and steel shim plates in alternate layer, has made it difficult to measure damping value. Damping is a dissipation of energy or energy losses in the vibration of the structure. Measuring the accurate amount of damping is fundamental as damping plays a crucial role in fixing the borderline between stability and instability in structural systems. Therefore, to determine the damping value including dynamic properties in any materials, modal analysis can be used. Hence, the main objective of this research is to determine the Rayleigh’s damping coefficients α and β and to evaluate the performance of the laminated rubber bearing using finite element and experimental modal analysis. Finding shows that, the finite element modal analysis with the addition of Rayleigh’s damping coefficients α and β, shows a good agreement with the experimental modal analysis in term of natural frequencies and mode shapes. Findings show that, the values of natural frequencies reduced when precise Rayleigh’s damping coefficient added in the finite element modal analysis. It can be concluded that both finite element and experimental modal analysis method can be used to estimate the accurate values of damping ratio and to determine the Rayleigh’s damping coefficients α and β as well.

scholarly journals Crack development assessment using modal analysis in peridynamic theory

2020 ◽  
Author(s):  
Andris Freimanis ◽  
Ainars Paeglitis
Keyword(s):  
Modal Analysis ◽  
Structural Damage ◽  
Mode Shapes ◽  
Displacement Fields ◽  
Local Alternative ◽  
Source Program ◽  
Attractive Option ◽  
Discontinuous Displacement ◽  
Similar Accuracy ◽  
Development Assessment

Abstract If structural damage remains undetected and is allowed to grow, structure's load-bearing capacity deteriorates, which can lead to costly repairs or in extreme cases its collapse. Modal analysis is widely used to detect structural damage because, when damage, such as cracks, is introduced, structure's geometrical and/or mechanical properties change, and these changes can be used for damage detection. Peridynamics is a non-local alternative to the continuum mechanics theory that represents forces and displacements using integral equations, which are defined even with discontinuous displacement fields, thus making this theory an attractive option for damage modeling. In this paper, authors verify peridynamic (PD) modal analysis against finite-element (FE) results, and validate it against experimental modal analysis results. The modal solver was implemented in the open-source program Peridigm and four different damage configurations were considered for verification and validation. The results show close agreement between the PD and the FE results, and the PD and the experimental results. Moreover, PD modal frequencies are shown to have similar accuracy to experimental data as the FE results. It is also shown that the frequency shifts are comparable between all three types of modal analysis. The PD mode shapes agreed well with both the FE and the experimental mode shapes at all considered damage configurations. Furthermore, the change in mode shapes from the introduced damage is similar in all three analyses.

INVESTIGATION OF DYNAMIC PROPERTIES OF ELASTOMERIC BEARING COMPONENTS VIA MODAL ANALYSIS

2015 ◽  
Vol 76 (8) ◽  
Author(s):  
A. I. Yusuf ◽  
M. A. Norliyati ◽  
M. A. Yunus ◽  
M. N. Abdul Rani
Keyword(s):  
Modal Analysis ◽  
Dynamic Behavior ◽  
Natural Frequencies ◽  
Dynamic Properties ◽  
Experimental Modal Analysis ◽  
Mode Shapes ◽  
Seismic Loads ◽  
Ground Structure ◽  
Elastomeric Bearing ◽  
Earthquake Load

Elastomeric bearing is a significant device in structures such as in bridges and buildings. It is used to isolate the ground structure (substructure) and the above ground structure (superstructure) from seismic loads such as earthquake load. Understanding the dynamic behavior of the elastomeric bearing in terms of natural frequencies, mode shapes and damping are increasingly important especially in improving the design and the failure limit of the elastomeric bearing. Modal analysis is one of the methods used to determine the dynamic properties of any materials. Hence, the main objective of this research is to determine the dynamic properties of elastomeric bearing components in terms of natural frequencies, mode shapes, and damping via numerical and experimental modal analysis. This method had been successfully performed in investigating the dynamic behavior of rubber and steel shim plate.

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