Ahmad Mahdian Parrany - Lecturer, Department of Mechanical Engineering, Vali-e-Asr University of Rafsanjan, Rafsanjan, Iran
Mohsen Mirzaei - Faculty Member, Department of Mechanical Engineering, Vali-e Asr University of Rafsanjan, Rafsanjan, Iran

Today piping systems play a crucial role in different industries. Since pipes usuallyexperience internal surface damages, damage detection in the pipes, using traditionalinspection methods, is not possible. Therefore, finding an effective method for detectinginternal damages in the pipes seems important. The primary goal of this paper is todemonstrate the effectiveness of using the wavelet transform to detect and localize theinternal damages in the pipes. One advantage of using the wavelet transform is that thismethod requires only one static or dynamic response of the wavelet transform is that this method requires only one static or dynamic response of the damaged structure, while noinformation about the intact structure is needed. In this paper, vibration mode shapes ofthe damaged structure are obtained using the ABAQUS numerical modeling softwarepackage, and then the wavelet analysis has been applied to detect localize the changesin the mode shapes. The damages have been modeled as a local reduction in the thicknessof the pipe and three different damage scenarios have been investigated. The continuouswavelet transform using Biorthogonal wavelet is used to get the spatially distributed wavelet coefficients. Meanwhile, a multiple-mode damage indicator based on the squaredresidual of the wavelet coefficients along spatial locations is proposed and its performance has been investigated via several numerical examples.

Structural health monitoring; Damage detection; Vibration mode shapes, Wavelet transform; Damage indicator