Damage Identification in Structures Based on Energy Curvature Difference of Wavelet Packet Transform

Pengbo Wang,Qinghe Shi

doi:10.1155/2018/4830391

Abstract

Damage identification is of tremendous significance in engineering structures. One key issue in damage identification is to determine an index that is sensitive to the structural damage. Current damage identification indices are generally focused on dynamic characteristics such as the natural frequencies, modal shapes, frequency responses, or their mathematical combinations. In this study, based on the wavelet packet transform, we propose a novel index, the energy curvature difference (ECD) index, to identify the damage in structures. The ECD index is the summation of component energy curvature differences after a signal is decomposed using WPT. Moreover, two numerical examples are used to demonstrate the feasibility and validity of the proposed ECD index for damage identification. Stiffness reduction is employed to simulate the structural damage. The damage can be identified by the ECD index curve plot. The results of the examples indicate that the proposed ECD index is sensitive to low damage levels because even 5% stiffness reduction can be apparently identified. The proposed ECD index can be employed to effectively identify structural damage.

Highlights

Damage is a serious threat to structures during their service life, and a damage identification technology is of tremendous significance in engineering applications
Current damage identification indices are generally focused on dynamic characteristics such as the natural frequencies, modal shapes, frequency responses, or their mathematical combinations
The ECD index is the summation of component energy curvature differences after a signal is decomposed using wavelet packet transform (WPT)

Summary

Introduction

Damage is a serious threat to structures during their service life, and a damage identification technology is of tremendous significance in engineering applications. Wavelet packet energy can be obtained in different frequency bands after a signal is decomposed using WPT. Some researchers have used curvature difference based on wavelet packet energy to locate the damage in ancient wood structures, concrete frames, and bridges [26–29]. In this study, based on the WPT, we propose a novel index, the energy curvature difference (ECD) index, to identify the damage in structures. The ECD index is the summation of component energy curvature differences after a signal is decomposed using WPT. It takes into account the spatial distribution of the collected signals and is sensitive to low damage levels because even a 5% stiffness reduction can be apparently identified.

Basics of Wavelet Packet Transform

Damage Identification Based on Energy Curvature Difference

Numerical Examples

Findings

Conclusions