Defect detection in FRP-bonded structural system via phase-based motion magnification technique

Abstract

Fiber-reinforced polymer (FRP)-bonded structural systems have been increasingly used in the field of civil infrastructure. Despite the outstanding advances in the applications of these structures, the interfacial defect between FRP composite and basis material occurs frequently during the designed service life. This type of defect can severely reduce the system integrity, which requires appropriate methods for defect detection in order to control the structural health state. This paper presents a novel approach of using phase-based motion magnification technique for detection of interfacial defect in FRP-bonded structural system. The research demonstrates that this video processing technique can effectively amplify the small surface motion at the defect location of FRP-bonded panel exposed to an air blow. The defect location and shape can be distinguished from the surrounding intact region, given that the two important parameters of bandpass frequency range and motion amplification factor are appropriately selected. Based on the research findings, a suitable defect detection scheme towards the FRP-bonded structural systems via this computational technique is established. The offered methodology does not require sensor installation and wiring, which enables an inexpensive and practical way for structural assessment.