Effect of Crack Location and Crack Depth on Natural Frequencies of Fixed Beam Using Experimental Modal Analysis

2019 ◽  
pp. 93-103
Author(s):  
Siva Sankara Babu Chinka ◽  
Balakrishna Adavi ◽  
Srinivasa Rao Putti
Keyword(s):  
Modal Analysis ◽  
Natural Frequencies ◽  
Crack Depth ◽  
Experimental Modal Analysis ◽  
Crack Location ◽  
Fixed Beam

scholarly journals Residual life estimation of structural beam using experimental and numerical modal analysis methods

2020 ◽  
Vol 4 (2) ◽  
pp. 135-146
Author(s):  
Ganda Anand Siva ◽  
Shinigam Ramakrishna
Keyword(s):  
Modal Analysis ◽  
Natural Frequencies ◽  
Residual Life ◽  
Crack Depth ◽  
Common Element ◽  
Cracked Beam ◽  
Element Analysis ◽  
Crack Location ◽  
Parametric Studies ◽  
Ship Propeller

A structural beam is a common element in many mechanical structures such as ship propeller shaft, crane boom, and air craft wings. In the present paper experimental and numerical modal analysis are carried out for estimating the damage detection, geometric location of the damage, severity of damage and residual life of structural beam to prevent unexpected failures of the mechanical structures. Experimental and numerical modal analysis results for healthy and cracked beam are compared for validation of numerical methodology used in the present paper. Experimental modal analysis is performed on both healthy and cracked beam with the help of impact hammer, acceleration sensor and FFT analyzer associated with EDM (Engineering Data Management) software. Modal tests are conducted using impact method on selected locations of the entire healthy and cracked beam to find the first three natural frequencies, which are used to detect the presence of damage and geometric location of the damage. Three parametric studies are carried out to know the effect of crack depth, crack location and crack orientation on the natural frequencies of the cracked beam. Finally,  residual life of a healthy and cracked beam was estimated using Basiquin’s equation and finite element analysis software called ANSYS 18.1.

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 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

Experimental Modal Analysis of Fan Vibration Frequency

2011 ◽  
Vol 138-139 ◽  
pp. 395-398
Author(s):  
Li Jun Wang ◽  
Zhi Yang Pan
Keyword(s):  
Modal Analysis ◽  
Vibration Frequency ◽  
Natural Frequencies ◽  
Experimental Modal Analysis ◽  
Resonance Vibration ◽  
Pneumatic Conveying ◽  
Combine Harvester

Fan is used for pneumatic conveying grain in the 4ZTL-1800 combine harvester threshing prior to cutting. In order to decrease power consume of it, the experimental modal analysis of fan was done by using hammer-hitting pulse-inspirit method. The natural frequencies of fan vibration is obtained, which is contrasted with inspirit frequency of fan, then resonance vibration of fan is found and its frequency is at 125Hz, which verifies the result of the experimental modal analysis.The results are beneficial to decrease power consume of fan.

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.

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.

Finite Element Modal Analysis for Steam Turbine Blade Based on ANSYS

2012 ◽  
Vol 260-261 ◽  
pp. 368-371
Author(s):  
Lu Wang ◽  
Shun Qiang Ye ◽  
Rui Meng
Keyword(s):  
Finite Element ◽  
Modal Analysis ◽  
Steam Turbine ◽  
Turbine Blade ◽  
Natural Frequencies ◽  
Crack Location ◽  
Finite Element Software ◽  
Vibration Fatigue ◽  
Steam Turbine Blade ◽  
Twisting Deformation

In response to the vibration fatigue fracture of the steam turbine blade,we construct the 3D model of cracked blade based on the actual crack location,then modal analysis is conducted to the blade with crack and one without crack using the finite element software ANSYS.Thus,we can get the respective natural frequencies and the figure of main vibration modes.The comprasion results show that the existence of the crack can make the natural frequencies of blades drop and the blades have the greatest sway and twisting deformation along the Y axis.These characteristics above can effectively identify the presence of blade cracked. It has crucial meaning for achieving cracked blade online monitoring.

Detection of Cracks in Stationary Rotors via the Modal Frequency Changes Induced by a Roving Disc

2014 ◽  
Author(s):  
Z. N. Haji ◽  
S. O. Oyadiji
Keyword(s):  
Natural Frequencies ◽  
Crack Depth ◽  
Mode Shapes ◽  
Crack Identification ◽  
Open Crack ◽  
Suggested Approach ◽  
Rotor Systems ◽  
Crack Location ◽  
High Crack ◽  
Frequency Changes

In this study, a crack identification approach based on a finite element cracked model is presented to identify the location and depth ratios of a crack in rotor systems. A Bernoulli-Euler rotor carrying an auxiliary roving disc has been used to model the cracked rotor, in which the effect of a transverse open crack is modelled as a time-varying stiffness matrix. In order to predict the crack location in the rotor-disc-bearing system, the suggested approach utilises the variation of the normalized natural frequency curves versus the non-dimensional location of a roving disc which traverses along the rotor span. The merit of the suggested approach is to identify the location and sizes of a crack in a rotor by determining only the natural frequencies of the stationary rotor system. The first four natural frequencies are employed for the identification and localisation of a crack in the stationary rotor. Furthermore, this approach is not only efficient and practicable for high crack depth ratios but also for small crack depth ratios and for a crack close to or at the node of mode shapes, where natural frequencies are unaffected.

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