Service and maintenance damage assessment of composite structures using various modes of infrared thermography

Abstract

Carbon Fibre Reinforced Polymers (CFRPs) have been widely used recently in aerospace technology as primary materials. During aircraft operation the combination of thermo-mechanical loads, gradually degrades the material properties. Therefore, the development of reliable and cost effective damage inspection protocols throughout the service life of these structures is of primary importance for their safe function. Within the scope of this study, Infrared Thermography (IrT) was employed with the aim of assessing the structural integrity of composite aero-structures in both maintenance (off-line) and service (on-line) conditions. In the maintenance concept, IrT was employed in Lock-in mode to evaluate artificially induced damage in bonded repaired materials. For this purpose, various configurations of damage were investigated. In the service concept, IrT was employed for the continuous monitoring of loaded repaired structures in order to assess in real-time any progressive evolution of de-bonding which could lead to failure of the bonded patch repair. The experimental results provided evidence that IrT is capable of qualitative and quantitative field assessment of aero-structures.