In-Plane Vibration and Crack Detection of a Rotating Shaft-Disk Containing a Transverse Crack

1998 ◽  
Vol 120 (2) ◽  
pp. 551-556 ◽  
Author(s):  
Ming-Chuan Wu ◽  
Shyh-Chin Huang
Keyword(s):  
Crack Detection ◽  
Transverse Crack ◽  
Rotation Speed ◽  
Crack Depth ◽  
Multiple Scale ◽  
Crack Identification ◽  
Response Curves ◽  
Rotating Shaft ◽  
Crack Location ◽  
Depth Rotation

Dynamic response and stability of a rotating shaft-disk containing a transverse crack is investigated. FFT analysis of response amplitudes showed that the 2Ω component (Ω: rotation speed) was excited by crack breathing and could serve as a good index for crack identification. Intensive numerical studies of crack location, crack depth, rotation speed, and sensing position on response amplitudes displayed a feasible technique for the identification of crack depth and crack location. It is achieved by intersecting the two equi-amplitude response curves of two separated sensing probes. Finally, the instability of the system caused by a crack is examined via Floquet theory and the multiple scale method. The stability diagrams, illustrated as functions of crack depth, rotation speed, and damping, are shown and discussed.

Crack Identification in a Rotating Shaft via the Reverse Directional Frequency Response Functions

2009 ◽  
Vol 131 (1) ◽  
Author(s):  
Yun-Ho Seo ◽  
Chong-Won Lee ◽  
K. C. Park
Keyword(s):  
Frequency Response ◽  
Transverse Crack ◽  
Crack Identification ◽  
Response Functions ◽  
Flexible Rotor ◽  
Rotating Shaft ◽  
Frequency Response Functions ◽  
Rotor Systems ◽  
Crack Location ◽  
Reference Map

A method is proposed for identifying the location of an open transverse crack in flexible rotor systems by modeling the crack as a localized element with rotating asymmetry. It exploits the strong correlations between the modal constants of the reverse directional frequency response functions (r-dFRFs) and the degree and location of asymmetry. A map of the modal constants of the r-dFRFs for all elements is constructed to identify the location of crack by comparing the identified modal constants to those of the reference map. This paper also addresses practical issues associated with measurement noises and limited number of sensors. The proposed crack identification method is finally applied to a flexible rotor system with an open transverse crack in order to demonstrate the identification procedure for detection of the crack location.

Dynamic Behaviour and Crack Detection of a Multi Cracked Rotating Shaft using Adaptive Neuro-Fuzzy-Inference System

2016 ◽  
Vol 6 (4) ◽  
pp. 1-10 ◽  
Author(s):  
Rajeev Ranjan
Keyword(s):  
Finite Element ◽  
Fuzzy Inference System ◽  
Crack Detection ◽  
Fuzzy Inference ◽  
Crack Depth ◽  
Multiple Cracks ◽  
Rotating Shaft ◽  
Element Analysis ◽  
Inference System ◽  
Neuro Fuzzy

The presence of crack changes the physical characteristics of a structure which in turn alter its dynamic response characteristics. So it is important to understand dynamics of cracked structures. Crack depth and location are the main parameters influencing the vibration characteristics of the rotating shaft. In the present study, a technique based on the measurement of change of natural frequencies has been employed to detect the multiple cracks in rotating shaft. The model of shaft was generated using Finite Element Method. In Finite Element Analysis, the natural frequency of the shaft was calculated by modal analysis using the software ANSYS. The Numerical data were obtained from FEA, then used to train through Adaptive Neuro-Fuzzy-Inference System. Then simulations were carried out to test the performance and accuracy of the trained networks. The simulation results show that the proposed ANFIS estimate the locations and depth of cracks precisely.

Dynamic Responses of a Cracked Gas-Bearing Spindle

2004 ◽  
Author(s):  
Bo-Wun Huang ◽  
Jao-Hwa Kuang
Keyword(s):  
Rotation Speed ◽  
Crack Depth ◽  
Applied Pressure ◽  
Equation Of Motion ◽  
Dynamic Responses ◽  
Bernoulli Beam ◽  
Spindle System ◽  
Depth Rotation ◽  
Euler Bernoulli Beam ◽  
Gas Bearing

The dynamic response of a cracked gas-bearing spindle system is studied in this work. A round Euler-Bernoulli beam is used to approximate the spindle system. The stiffness effect of the gas bearing spindle is considered as massless springs and the Hamilton principle is employed to derive the equation of motion for the spindle system. The effects of crack depth, rotation speed and air applied pressure on the dynamic characteristics of a rotating gas-bearing spindle system are studied.

Crack Identification in a Cantilever Beam Using Coupled Response Measurements

1998 ◽  
Vol 120 (4) ◽  
pp. 775-777 ◽  
Author(s):  
A. S. Sekhar ◽  
P. Balaji Prasad
Keyword(s):  
Cantilever Beam ◽  
Crack Detection ◽  
Rate Of Change ◽  
Crack Identification ◽  
Direct Response ◽  
Crack Location ◽  
Small Cracks ◽  
Axial Response ◽  
Coupled Response ◽  
System Characteristics

Identification of crack location and magnitude through measurement in changes in system characteristics, such as modal measurements, has been studied by various researchers. In the present work based on the new method proposed by Gounaris et al. (1996) for crack detection through coupled response measurements, experiments were carried out on a cracked cantilever beam for eigenfrequencies, bending, and axial response measurements. It has been observed that the rate of change of direct response (bending) is much less at small cracks, while that of the coupled response (axial) changes substantially, which allows for diagnoses of smaller cracks.

Analysis of the Elastic Wave Behavior in a Cracked Shaft

2007 ◽  
Author(s):  
Kelsen LaBerge ◽  
Maurice Adams
Keyword(s):  
Crack Detection ◽  
Acoustic Velocity ◽  
New Method ◽  
Proof Of Concept ◽  
Test Apparatus ◽  
Rotating Shaft ◽  
One Dimensional ◽  
Crack Location ◽  
The Impact ◽  
Cracked Shaft

A new method currently under development for rotating shaft crack detection is presented. The underlying approach is to utilize the impact inherent in the once-per-revolution closing of a shaft crack. The axially traveling elastic compression wave, which is initiated by this impact, propagates to both ends of the shaft at the governing acoustic velocity. Provided suitable measurement near the shaft ends can detect the wave’s arrival, then extracting both the crack location and size is thereby feasible. Proof-of-concept for this new method for shaft crack detection utilizes one-dimensional wave propagation simulations and a newly designed test apparatus, which are presented.

A study on the crack detection in beams using linear and nonlinear normal modes

2019 ◽  
Vol 23 (7) ◽  
pp. 1305-1321
Author(s):  
Yildirim Serhat Erdogan
Keyword(s):  
Normal Mode ◽  
Crack Detection ◽  
Normal Modes ◽  
Element Model ◽  
Nonlinear Normal Modes ◽  
Crack Identification ◽  
Crack Location ◽  
Linear And Nonlinear ◽  
Nonlinear Normal ◽  
Cracked Beams

Linear and nonlinear normal mode motions may provide promising information about the condition of mechanical structures under small and large amplitude vibrations, respectively. In this view, this study investigates the nonlinear dynamics of cracked beams through use of the nonlinear mode motion and extends the crack identification methods that utilize the linear characteristics to nonlinear vibrating structures. At first, the nonlinear normal modes of the intact and cracked beams are calculated by a continuation algorithm. A finite element model of a geometrically nonlinear prismatic beam was created based on crack stress intensity. Subsequently, a method based on normal mode motion and minimization of strain energy, which is valid for linear and nonlinear vibrating beams, was developed as an optimization problem. To this end, hybrid optimization was also used due to its capability in finding global minimum along with its computational efficiency. It was shown that the proposed crack detection technique is applicable to beams vibrating in linear and/or nonlinear regimes and well capable of detecting both crack location and severity.

Dynamic Behaviour and Crack Detection of a Multi Cracked Rotating Shaft using Adaptive Neuro-Fuzzy-Inference System

Fuzzy Systems ◽  
2017 ◽  
pp. 1540-1551
Author(s):  
Rajeev Ranjan
Keyword(s):  
Finite Element ◽  
Fuzzy Inference System ◽  
Crack Detection ◽  
Fuzzy Inference ◽  
Crack Depth ◽  
Rotating Shaft ◽  
Inference System ◽  
Response Characteristics ◽  
Neuro Fuzzy ◽  
Cracked Structures

The presence of crack changes the physical characteristics of a structure which in turn alter its dynamic response characteristics. So it is important to understand dynamics of cracked structures. Crack depth and location are the main parameters influencing the vibration characteristics of the rotating shaft. In the present study, a technique based on the measurement of change of natural frequencies has been employed to detect the multiple cracks in rotating shaft. The model of shaft was generated using Finite Element Method. In Finite Element Analysis, the natural frequency of the shaft was calculated by modal analysis using the software ANSYS. The Numerical data were obtained from FEA, then used to train through Adaptive Neuro-Fuzzy-Inference System. Then simulations were carried out to test the performance and accuracy of the trained networks. The simulation results show that the proposed ANFIS estimate the locations and depth of cracks precisely.

A Novel Real Time Diagnostic Method for Crack Detection on a Rotating Shaft

2009 ◽  
Author(s):  
Fernando A. Bejarano ◽  
Amilcar A. Rincon ◽  
Yamil Camacho ◽  
Xaymara Perereira
Keyword(s):  
Real Time ◽  
Crack Detection ◽  
Element Model ◽  
Crack Size ◽  
Detection Sensitivity ◽  
Crack Identification ◽  
Open Crack ◽  
Rotating Shaft ◽  
Function Approximator ◽  
Vibration Parameters

This paper presents a novel real-time crack identification method to determine the position and depth of a transverse open crack on a rotating shaft. Wireless accelerometer capable of being mounted directly on the shaft is employed to monitor acceleration at different points of the shaft in a rotating coordinate system. The vibration parameters obtained from the wireless sensors and Finite Element Model provide operational data to perform Modal Analysis with different mock crack positions and depths, and an unique relation between the vibration parameters and crack characteristics is developed by Neural Networks Method working as function approximator to predict the crack size and location on the shaft. The method was experimentally validated and results have shown that the crack detection sensitivity parameters depend on the acceleration signals at different points of the shaft.

The effect of crack geometry on non-destructive fault detection of EN 8 and EN 47 cracked cantilever beam

2019 ◽  
Vol 50 (3) ◽  
pp. 92-100 ◽  
Author(s):  
V Khalkar ◽  
S Ramachandran
Keyword(s):  
Free Vibration ◽  
Natural Frequency ◽  
Cantilever Beam ◽  
Crack Detection ◽  
Crack Depth ◽  
Free Vibration Analysis ◽  
Crack Location ◽  
Crack Geometry ◽  
Shaped Crack ◽  
Non Destructive

Since long it has been observed that the size of the crack in structures increases with time, and finally, it may lead to its catastrophic failure. Hence, it is crucial to do the vibration study of cracked structures with regard to vibration-based crack detection and the classification of cracks. So far, vibration-based non-destructive testing method is applied to many spring steel cracked cantilever beams for its possible crack detection. However, the effect of various kinds of practical cracks, that is, V-shaped and U-shaped, on the applicability of these methods has been overlooked. To investigate this issue, artificially cracks are made on the cantilever beam. By free vibration analysis, the effect of crack geometry, crack depth, and crack location on natural frequency is investigated. The natural frequency results obtained from V-shaped and U-shaped models for the same crack configurations are compared with each other and it is revealed that the results are not much sensitive for the change of crack geometry. Hence, it is clear that free vibration-based crack detection method approximately predicts the crack parameters, that is, crack location and crack depth, in structures irrespective of the crack geometry. It is also found that for the same configuration, results of natural frequency are comparatively on the lower side for U-shaped crack models than V-shaped crack models. In this study, the natural frequency of each cracked case is computed by a theoretical method and numerical method and shows good agreement. Finally, it is also observed that structural integrity of a cracked cantilever beam is a function of crack location.

scholarly journals Crack Identification in a Cantilever Beam Using Coupled Response Measurements

1997 ◽  
Author(s):  
A. S. Sekhar ◽  
P. Balaji Prasad
Keyword(s):  
Cantilever Beam ◽  
Crack Detection ◽  
Rate Of Change ◽  
Crack Identification ◽  
Direct Response ◽  
Crack Location ◽  
Small Cracks ◽  
Axial Response ◽  
Coupled Response ◽  
System Characteristics

Identification of crack location and magnitude through measurement in changes in system characteristics, such as modal measurements has been studied by various researchers. In the present work based on the new method proposed by Gounaris et al (1996) for crack detection through coupled response measurements, experiments were carried out on a cracked cantilever beam for eigenfrequencies, bending and axial response measurements. It has been observed that the rate of change of direct response (bending) is much less at small cracks while that of the coupled response (axial) changes, substantially allowing diagnoses of smaller cracks.

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