scholarly journals Wavelet based technique for multi-crack detection of a beam-like structure using the vibration data measured directly from a moving vehicle

2010 ◽  
Vol 32 (4) ◽  
pp. 222-234 ◽  
Author(s):  
Nguyen Viet Khoa ◽  
Tran Thanh Hai
Keyword(s):  
Wavelet Transform ◽  
Dynamic Response ◽  
Crack Detection ◽  
Crack Model ◽  
Vehicle Speed ◽  
Low Velocity ◽  
Cracked Beam ◽  
Moving Vehicle ◽  
Vibration Data ◽  
Beam Height

In this paper an idea for crack detection of a multi-cracked beam-like structure by analyzing the vibration measured directly from the vehicle is presented. The crack model is adopted from fracture mechanics. The dynamic response of the bridge-vehicle system is measured directly from the moving vehicle. When the vehicle moves along the structure, the dynamic response of the vehicle is distorted by the cracks at their locations. These distortions are generally small and difficult to be detected visually. In order to detect the cracks, Wavelet Transform - an effective method of detecting such small distortions was adopted. The existence of the cracks can be revealed by large values (peaks) in the wavelet transform. Locations of the cracks can be determined by positions of the peaks and the vehicle speed. Numerical results show that the method can detect cracks as small as 10 % of the beam height with noise level up to 5%. The proposed method is applicable for low velocity-movements while high velocity-movements are not recommended.

Crack detection of a beam-like bridge using 3D mode shapes

2014 ◽  
Vol 36 (1) ◽  
pp. 13-25
Author(s):  
Khoa Viet Nguyen
Keyword(s):  
Crack Detection ◽  
Rectangular Cross Section ◽  
Mode Shapes ◽  
Crack Model ◽  
Coupling Mechanism ◽  
Cracked Beam ◽  
Bending Vibrations ◽  
Space Curves ◽  
Beam Height ◽  
Beam Bridge

In this paper, mode shapes of a 3D cracked beam with a rectangular cross section are analyzed for crack detection. The influence of coupling mechanism between horizontal and vertical bending vibrations due to the 3D crack model on the mode shapes is investigated. Due to the coupling mechanism the mode shapes of a beam are twisted in space. They change from plane curves to space curves. This phenomenon can be used for crack detection. The existence of the crack can be detected when the mode shapes are space curves. Also, the mode shapes of a cracked beam bridge have distortions or sharp changes at the crack position. Therefore, the position of the crack can be determined as a position at which the mode shapes exhibit such distortions or sharp changes. Moreover, using the mode shapes in 3D crack model, a crack with depth as small as 1% of the beam height can be detected, while in previous studies using 2D crack model, distortions in the mode shapes caused by a small crack cannot be detected. These results are new and can be used for crack detection of a beam bridge. The stiffness matrix of a 3D cracked element obtained from fracture mechanics is presented and numerical simulations are provided in this paper. 

Dynamic Analysis of Non-Uniform Continuous Girder Bridge under Moving Vehicle

2011 ◽  
Vol 243-249 ◽  
pp. 1634-1637
Author(s):  
Zhi Gang Chen ◽  
Zi Lin Peng
Keyword(s):  
Dynamic Response ◽  
Dynamic Analysis ◽  
Numerical Solutions ◽  
Lagrange Equation ◽  
Field Testing ◽  
Vehicle Speed ◽  
Analysis Model ◽  
Moving Vehicle ◽  
Continuous Girder Bridge ◽  
The Impact

For non-uniform continuous bridge in actual projects, the theoretical analysis and field testing of the dynamic response under moving vehicle are carried out. Firstly, Euler-Lagrange equation is applied to derive the vibration equation of three-axle vehicle. Then one obtains the dynamic analysis model by using the finite element method and the vehicle-bridge interaction equation based on the displacement coordination relationship of the contact between wheels and bridge. Lastly, numerical solutions are presented according to the dynamic response of the bridge, compared with the real values. The results show that: the roadway roughness and vehicle speed strongly influence the impact factor.

Analysis of the Dynamic Response of a Cracked Beam Structure

2012 ◽  
Vol 187 ◽  
pp. 58-62 ◽  
Author(s):  
D. N. Thatoi ◽  
J. Nanda ◽  
H.C. Das ◽  
D.R. Parhi
Keyword(s):  
Finite Element ◽  
Dynamic Response ◽  
Cantilever Beam ◽  
Crack Detection ◽  
Dynamic Behaviour ◽  
Natural Frequencies ◽  
Mode Shapes ◽  
Cracked Beam ◽  
Local Flexibility ◽  
Good Agreement

In this research, dynamic behaviour of a cracked cantilever beam has been analysed using finite element and experimental analysis. Deviations in mode shapes and natural frequencies have been noticed due to the presence of crack in the beam. The variation in the dynamic response is due to change in local flexibility because of the presence of crack in the beam. Finite element and experimental analyses have been carried out to find out the vibration indices of the cracked cantilever beam for validating the robustness of the theoretical model used for crack detection. The numerical results obtained through FEA are in good agreement with experimental results.

Dynamic Response of Smart Hybrid Composite Plate Subjected to Low-Velocity Impact

2007 ◽  
Vol 41 (19) ◽  
pp. 2347-2370 ◽  
Author(s):  
S.M.R. Khalili ◽  
A. Shokuhfar ◽  
F. Ashenai Ghasemi ◽  
K. Malekzadeh
Keyword(s):  
Dynamic Response ◽  
Hybrid Composite ◽  
Composite Plate ◽  
Low Velocity Impact ◽  
Low Velocity ◽  
Velocity Impact ◽  
Hybrid Composite Plate

scholarly journals Homotopy Iteration Algorithm for Crack Parameters Identification with Composite Element Method

2013 ◽  
Vol 2013 ◽  
pp. 1-10
Author(s):  
Ling Huang ◽  
Zhongrong Lv ◽  
Weihuan Chen ◽  
Jike Liu
Keyword(s):  
Dynamic Responses ◽  
Iteration Algorithm ◽  
Crack Model ◽  
Open Crack ◽  
Time Duration ◽  
Cracked Beam ◽  
Composite Element ◽  
Direct Integration Method ◽  
Composite Element Method ◽  
Element Method

An approach based on homotopy iteration algorithm is proposed to identify the crack parameters in beam structures. In the forward problem, a fully open crack model with the composite element method is employed for the vibration analysis. The dynamic responses of the cracked beam in time domain are obtained from the Newmark direct integration method. In the inverse analysis, an identification approach based on homotopy iteration algorithm is studied to identify the location and the depth of a cracked beam. The identification equation is derived by minimizing the error between the calculated acceleration response and the simulated measured one. Newton iterative method with the homotopy equation is employed to track the correct path and improve the convergence of the crack parameters. Two numerical examples are conducted to illustrate the correctness and efficiency of the proposed method. And the effects of the influencing parameters, such as measurement time duration, measurement points, division of the homotopy parameter and measurement noise, are studied.

scholarly journals Dynamic Response of a Cracked Rotor With Some Comments on Crack Detection

1994 ◽  
Author(s):  
G. Meng ◽  
Eric J. Hahn
Keyword(s):  
Dynamic Response ◽  
Crack Detection ◽  
Harmonic Component ◽  
Major Axis ◽  
Vertical Axis ◽  
Crack Size ◽  
Cracked Rotor ◽  
Response Component ◽  
Crack Location ◽  
Backward Whirl

By considering time dependent terms as external excitation forces, the approximate dynamic response of a cracked horizontal rotor is analysed theoretically and numerically. The solution is good for small cracks and small vibrations in the stable operating range. For each steady state harmonic component the forward and backward whirl amplitudes, the shape and orientation of the elliptic orbit and the amplitude and phase of the response signals arc analysed, taking into account the effect of crack size, crack location, rotor speed and unbalance. It is found that the crack causes backward whirl, the amplitude of which increases with the crack. For a cracked rotor, the response orbit for each harmonic component is an ellipse, the shape and orientation of which depends on the crack size. The influence of the crack on the synchronous response of the system can be regarded as an additional unbalance whereupon, depending on the speed and the crack location, the response amplitude differs from that of the uncracked rotor. The nonsynchronous response provides evidence of crack in the sub-critical range, but is too small to be detected in the supercritical range. Possibilities for crack detection over the full speed range include the additional average (the constant) response component, the backward whirl of the response, the ellipticity of the orbit, the angle between the major axis and the vertical axis and the phase angle difference between vertical and horizontal vibration signals.

scholarly journals Exact receptance function and receptance curvature of a clamped-clamped continuous cracked beam

2019 ◽  
Vol 41 (4) ◽  
pp. 349-361
Author(s):  
Nguyen Viet Khoa ◽  
Cao Van Mai ◽  
Dao Thi Bich Thao
Keyword(s):  
Numerical Simulations ◽  
Frequency Domain ◽  
Crack Detection ◽  
Harmonic Excitation ◽  
Second Derivative ◽  
Cracked Beam ◽  
Cracked Beams

The receptance function has been studied and applied widely since it interrelates the harmonic excitation and the response of a structure in the frequency domain. This paper presents the derivation of the exact receptance function of continuous cracked beams and its application for crack detection. The receptance curvature is defined as the second derivative of the receptance. The influence of the crack on the receptance and receptance curvature is investigated. It is concluded that when there are cracks the receptance curvature has sharp changes at the crack positions. This can be applied for the crack detection purpose. In this paper, the numerical simulations are provided.

scholarly journals Spectral analysis of multiple cracked beam subjected to moving load

2014 ◽  
Vol 36 (4) ◽  
pp. 245-254
Author(s):  
N. T. Khiem ◽  
P. T. Hang
Keyword(s):  
Dynamic Response ◽  
Moving Load ◽  
Time History ◽  
Theoretical Development ◽  
Multiple Cracks ◽  
Spectral Approach ◽  
Cracked Beam ◽  
Time History Response ◽  
Numerical Case Study

In present paper, the spectral approach is proposed for analysis of multiple cracked beam subjected to general moving load that allows us to obtain explicitly dynamic response of the beam in frequency domain. The obtained frequency response is straightforward to calculate time history response by using the FFT algorithm and provides a novel tool to investigate effect of position and depth of multiple cracks on the dynamic response. The analysis is important to develop the spectral method for identification of multiple cracked beam by using its response to moving load. The theoretical development is illustrated and validated by numerical case study.

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