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.KEYWORDS computational technique, defect detection, fiber-reinforced polymer-bonded structural system, structural health assessment, system identification 1 | INTRODUCTION Fiber-reinforced polymer (FRP) material features its high specific stiffness and strength, good fatigue performance, and damage tolerance, which can effectively improve the flexural and shear capacity of engineering structures. 1-4 In construction and building technology, this composite has been widely used to strengthen the existing deficient concrete structures. Also, it can promote the wide utilization of wood materials in buildings due to the following two important benefits: (a) enhancing the load-carrying capacity of wood structural elements (e.g., beam and column) by bonding FRP and (b) saving the construction energy as wood is a renewable and green building material in comparison to cement, concrete, and steel. 2,5-8 Nevertheless, FRP-bonded structural system suffers from interface deterioration and defect initiation due to outside instant impact or environmental attacks. The deterioration of FRP-bonded wood structure can be more serious because the wood component is susceptible to chemical degradation, fungal infection, and entry of pathogens and insects. 9-13 Hence, the interfacial defect between the FRP and the substrate frequently occurs.

Deterioration Mechanisms and Advanced Inspection Technologies of Aluminum Windows

“…To prevent this from happening, many non-destructive testing (NDT) technologies have great potential for promoting the accuracy and efficiency of aluminum window defects inspection. NDT technologies are strategic procedures for gathering information on structure conditions and existing damage and defining adequate remedial measures; they have a powerful ability to assess health state in a non-invasive manner [ 14 , 15 , 16 ]. These advanced NDT technologies include ultrasonic thickness measurement technology, ultrasonic guided wave inspection, and active infrared thermographic inspection.…”