Finite Element Analysis of EMI Signatures of Damaged Structural Connection via High-Performance Interface Washer

Abstract

Structural connections are important parts of most infrastructures since the failure of the connections can lead to the loss of serviceability and structural collapse. Therefore, damage detection on structural connections has become an important topic. Among many technologies, impedance-based method has been found very promising for monitoring small incipient damage in critical members like structural connections. This study presents a finite element analysis of electro-mechanical impedance (EMI) signatures of damaged structural connections via a high-performance interface washer. To achieve the objective, the following approaches are implemented. Firstly, an interface washer is designed to monitor the changes in stress fields. The interface washer is a thin plate which is installed in structural connection. On the interface washer, a piezoelectric (PZT) patch is attached to monitor the changes in structural impedance by changes in stress fields. Secondly, a finite element model of structural connection such as cable anchor connection and bolted connection is established. In the finite element analysis, the interface washer is modeled to represent changes in stress fields on the connection by using impedance-based method. Also, the effects of material and geometrical properties of the interface washer on EMI signatures are examined to aim at designing the optimal interface washer. Thirdly, the feasibility of the finite element analysis is validated by experiments on a lab-scale cable anchor connection and a bolted connection.