scholarly journals Crack detection in simply supported beams using stationary wavelet transform of modal data

2011 ◽  
Vol 18 (2) ◽  
pp. 169-190 ◽  
Author(s):  
Shuncong Zhong ◽  
S. Olutunde Oyadiji
Keyword(s):  
Wavelet Transform ◽  
Crack Detection ◽  
Stationary Wavelet Transform ◽  
Simply Supported ◽  
Modal Data

Identification of Cracks in Beams With Auxiliary Mass Spatial Probing by Stationary Wavelet Transform

2008 ◽  
Vol 130 (4) ◽  
Author(s):  
Shuncong Zhong ◽  
S. Olutunde Oyadiji
Keyword(s):  
Wavelet Transform ◽  
Crack Detection ◽  
Natural Frequencies ◽  
Experimental Testing ◽  
Crack Depth ◽  
Accurate Estimation ◽  
Stationary Wavelet Transform ◽  
Crack Location ◽  
Order Curve ◽  
Auxiliary Mass

This paper proposes a new approach based on auxiliary mass spatial probing by stationary wavelet transform (SWT) to provide a method for crack detection in beamlike structure. SWT can provide accurate estimation of the variances at each scale and facilitate the identification of salient features in a signal. The natural frequencies of a damaged beam with a traversing auxiliary mass change due to the change in flexibility and inertia of the beam as the auxiliary mass is traversed along the beam. Therefore, the auxiliary mass can enhance the effects of the crack on the dynamics of the beam and, therefore, facilitate the identification and location of damage in the beam. That is, the auxiliary mass can be used to probe the dynamic characteristic of the beam by traversing the mass from one end of the beam to the other. However, it is difficult to locate the crack directly from the graphical plot of the natural frequency versus axial location of auxiliary mass. This curve of the natural frequencies can be decomposed by SWT into a smooth, low order curve, called approximation coefficient, and a wavy, high order curve called the detail coefficient, which includes crack information that is useful for damage detection. The modal responses of the damaged simply supported beams with auxiliary mass used are computed using the finite element method (FEM). Sixty-four cases are studied using FEM and SWT. The efficiency and practicability of the proposed method is illustrated via experimental testing. The effects of crack depth, crack location, auxiliary mass, and spatial probing interval are investigated. From the simulated and experimental results, the efficiency of the proposed method is demonstrated.

Numerical Studies on Wavelet-Based Crack Detection Based on Velocity Response of a Beam Subjecting to Moving Load

2013 ◽  
Vol 569-570 ◽  
pp. 854-859 ◽  
Author(s):  
Wei Wei Zhang ◽  
Jia Geng ◽  
Zi Long Zhao ◽  
Zhi Hua Wang
Keyword(s):  
Wavelet Transform ◽  
Damage Detection ◽  
Crack Detection ◽  
Moving Load ◽  
Noise Tolerance ◽  
Simply Supported Beam ◽  
Simply Supported ◽  
Damage Location ◽  
Numerical Studies ◽  
Velocity Response

In this paper, the possibility and validity of damage detection based on velocity response of a simply supported beam under the moving load are examined theoretically and numerically. It includes the following parts: First, the theoretic background of the beam vibration subjecting to moving load is briefly described. And then, the velocity responses of a simple supported beam are calculated by software Ansys. Using wavelet transform, the damage location can be identified successfully. At last, the effects of noise and load speed are discussed in detail. Numerical studies show the validity of the proposed method and a good noise tolerance using the velocity response.

Wavelet-Based Structural Damage Detection

2007 ◽  
Author(s):  
Shuncong Zhong ◽  
S. Olutunde Oyadiji
Keyword(s):  
Damage Detection ◽  
Structural Damage ◽  
Crack Detection ◽  
Damage Index ◽  
Multiple Cracks ◽  
Structural Damage Detection ◽  
Simply Supported ◽  
Modal Data ◽  
The Difference ◽  
Detail Coefficient

In this paper, a new wavelet-based approach for crack identification in beam-like structures is presented and applied to simply-supported beams with single or multiple cracks. A novel damage index, based on finding the difference between two sets of detail coefficients obtained by the use of the Stationary Wavelet Transform (SWT) of two reconstructed sets of modal displacement data of the cracked beam-like structure, is proposed for single crack detection or multiple crack detection. These two sets of mode shape data represent the left half and the modified right half of the modal data of the structure. Currently, SWT is widely used in the field of image processing for image noise reduction and image quality improvement. However, because it can provide an accurate estimate of the variances at each scale and facilitate the identification of salient features in a signal, SWT has great potential in the field of structural damage detection. In this paper, the modal responses of the damaged simply supported beams used are computed using the finite element method (FEM). The modal data generate is decomposed by SWT into a smooth curve, called approximation coefficient, and detail coefficient. It is shown that the detail coefficient includes crack information that is useful for structural damage detection. Therefore, a novel damage index, the difference of the SWT detail coefficients of two reconstructed sets of modal displacement data, is proposed and employed. The numerical simulation results show that the proposed wavelet-based method has a good anti-noise ability and it does not require the modal parameters of an intact structure as a baseline for crack detection. Therefore, it can be recommended for real applications in structural health monitoring and damage detection.

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