Abstract
This paper reports on a two-step approach for optimally determining the location and severity of damage in beam structures under flexural vibration. The first step focuses on damage location detection. This is done by defining the damage index called relative wavelet packet entropy (RWPE). The damage severities of the model in terms of loss of stiffness are assessed in the second step using the inverse solution of equations of motion of a structural system in the wavelet domain. For this purpose, the connection coefficient of the scaling function to convert the equations of motion in the time domain into the wavelet domain is applied. Subsequently, the dominant components based on the relative energies of the wavelet packet transform (WPT) components of the acceleration responses are defined. To obtain the best estimation of the stiffness parameters of the model, the least squares error minimization is used iteratively over the dominant components. Then, the severity of the damage is evaluated by comparing the stiffness parameters of the identified model before and after the occurrence of damage. The numerical and experimental results demonstrate that the proposed method is robust and effective for the determination of damage location and accurate estimation of the loss in stiffness due to damage.
Highlights
Damage detection and condition monitoring of structures have become ever-increasing concerns.Most of the available techniques are based on visual inspection or localized assessment procedures such as ultrasonic, acoustic and impact echo which can be generated due to characteristic changes in the material
The results demonstrate that the locations of damage can be successfully determined from the measured time history acceleration responses through the variation of relative wavelet packet entropy (RWPE)
In Case 1, where the damage was located between two sensors, the damage location could be clearly identified with the change in values of RWPE
Summary
Damage detection and condition monitoring of structures have become ever-increasing concerns.Most of the available techniques are based on visual inspection or localized assessment procedures such as ultrasonic, acoustic and impact echo which can be generated due to characteristic changes in the material. Damage detection and condition monitoring of structures have become ever-increasing concerns. The purpose of structural health monitoring is to evaluate the condition of the structure and to identify damage when it occurs. For this reason, analysis techniques that identify structural damage using vibration data obtained from sensors have garnered widespread interest. The theory of vibration-based SHM is that the dynamic characteristics of a structure are a function of its physical properties. When there are changes in these physical properties, such as a decrease in stiffness due to localized structural damage, there will be corresponding changes in the dynamic characteristics of the structure
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