Critical Issues Affecting the Performance of PWAS Based SHM Systems for Corrosion Detection of Aluminum Structures

Abstract

Structural health monitoring (SHM) techniques for early detection of corrosion damage include guided waves techniques based on the use of piezoelectric wafer active sensors (PWAS) bonded to the structure to be monitored. A reliable SHM system using PWAS is affected by several issues, including the type of the adhesive used to bond the PWAS to the substrate, the environment on the signals measured and the introduction of controlled defects to simulate corrosion damage. This paper investigates the above mentioned issues applied to a PWAS based SHM system for corrosion detection in aluminum structures. Two types of adhesives are investigated, namely epoxy and cyanoacrylate resins. They are compared in regard to long term and thermal properties. The difference in regard to their performance is traced to the degree of cure of the resins and to their glass transition temperature. Furthermore, electrochemical etching is introduced as an efficient tool to simulate corrosion damage in aluminum.