Inverse analysis for damage detection in a rod using EMI method

Abstract

The electro-mechanical impedance (EMI) method has been demonstrated to be a powerful tool to detect the small local damages in various engineering structures, due to its high-frequency vibration characteristics. However, this technique is difficult to accurately determine the degree and location of structural damages. In this paper, an inverse analysis combining the measured EMI signatures and the Transfer Matrix Method (TMM) is proposed to identify the damages in the steel rods. A milled groove is introduced into each steel specimen to simulate the local damage. By measuring the EMI signatures of the piezoelectric wafers bonded symmetrically on the upper and lower surfaces of the rectangular specimens respectively, the damage can be detected clearly, as well as natural frequencies being extracted in the relatively lower frequency range. The damage sizes and locations are further determined by connecting the frequency equations and any two measured natural frequencies. Tests on three samples show both damage sizes and locations are accurately detected, which indicates that the present method is quite feasible and effective for damage identification in the bar-type structures.

Keywords:

• Electro-mechanical impedance
• transfer matrix method
• steel rods
• damage detection
• free vibration analysis

Additional information

Funding

The research is supported by the Applied Research Project of Public Welfare Technology in Zhejiang Province (Grant No. LGF21E080004), and the K.C. Wong Magna Fund of Ningbo University.